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A Model and Questionnaire of Language Identity in Iran: A Structural Equation Modelling Approach
ERIC Educational Resources Information Center
This study consisted of three main phases including the development of a hypothesised model of language identity in Iran, developing and validating a questionnaire based on this model and finally testing the model based on the questionnaire data. In the first phase of this research, a hypothesised model of language identity in Iran was developed…
Khatib, Mohammad; Rezaei, Saeed
Paper to Electronic Questionnaires: Effects on Structured Questionnaire Forms
NASA Technical Reports Server (NTRS)
With the use of computers, paper questionnaires are being replaced by electronic questionnaires. The formats of traditional paper questionnaires have been found to effect a subject's rating. Consequently, the transition from paper to electronic format can subtly change results. The research presented begins to determine how electronic questionnaire formats change subjective ratings. For formats where subjects used a flow chart to arrive at their rating, starting at the worst and middle ratings of the flow charts were the most accurate but subjects took slightly more time to arrive at their answers. Except for the electronic paper format, starting at the worst rating was the most preferred. The paper and electronic paper versions had the worst accuracy. Therefore, for flowchart type of questionnaires, flowcharts should start at the worst rating and work their way up to better ratings.
Trujillo, Anna C.
Measurement invariance of the Childhood Trauma Questionnaire across gender and race\\/ethnicity: Applications of structural equation modeling and item response theory
Microsoft Academic Search
Research has established associations between child maltreatment and a wide range of deleterious psychological sequelae for both women and men across racial\\/ethnic groups. This research, however, tends to be marked by methodological pitfalls, one of which has been the use of non-standardized retrospective measurement instruments that have not been subjected to rigorous validation procedures. The Childhood Trauma Questionnaire (CTQ-SF; Bernstein
Brett D Thombs
The Tridimensional Personality Questionnaire: Structural Validity and Comparison with the Multidimensional Personality Questionnaire.
The structural and external validity of the Tridimensional Personality Questionnaire (TPQ) and the relations among TPQ lower-order and higher-order scales and those of the Multidimensional Personality Questionnaire were examined. Results for 1,236 adults support the TPQ's validity but indicate its failure to operationalize portions of the…
Waller, Niels G.; And Others
Structural Equation Model Trees
In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…
Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman
Selective Mutism Questionnaire: Measurement Structure and Validity
The psychometric properties of the Selective Mutism Questionnaire (SMQ) are evaluated using a clinical sample of children with selective mutism (SM). The study shows that SMQ is useful in determining the severity of a child's nonspeaking behaviors, the scope of these behaviors and necessary follow up assessment.
Letamendi, Andrea M.; Chavira, Denise A.; Hitchcock, Carla A.; Roesch, Scott C.; Shipon-Blum, Elisa; Stein, Murray B.
Hand Test and the High School Personality Questionnaire: structural analysis.
The Hand Test and the High School Personality Questionnaire were administered to 15 boys and 15 girls in Grades 9 and 10 transferred to an alternative school for acting-out behavior. They were of average intelligence. Several significant correlations between Hand Test and High School Personality Questionnaire variables were noted. Results are discussed in reference to Structural Analysis. PMID:6371701
McGiboney, G W; Carter, C; Jones, W
Nonlinear dynamical structural equation models
Structural equation models (SEMs) have been widely used in behavioural, educational, medical and socio-psychological research for exploring and confirming relations among observed and latent variables. In the existing SEMs, the unknown coefficients in the measurement and structural equations are assumed to be constant with respect to time. This assumption does not always hold, as the relation among the observed and
Wenyang Zhang; Sik-Yum Lee
The Structure and Validity of the Multidimensional Social Support Questionnaire
The factor structure and concurrent validity of the Multidimensional Social Support Questionnaire, a brief measure of perceived social support for use with adolescents, was examined. Findings suggest that four dimensions of perceived social support may yield more information than assessments of the unitary construct of support. (Contains 8 tables…
Hardesty, Patrick H.; Richardson, George B.
The Infant Crying Questionnaire: Initial Factor Structure and Validation
PubMed Central
The current project reports on an initial investigation into the factor structure of the Infant Crying Questionnaire (ICQ), a measure designed to assess parental beliefs about infant crying, in a sample of 259 primiparous mothers. Exploratory factor analyses yielded evidence for a five-factor structure to the ICQ, with two factors that may be conceptually viewed as infant-oriented beliefs regarding infant crying (Attachment/Comfort and Crying as Communication) and three factors conceptually reflecting parent-oriented beliefs regarding infant crying (Minimization, Directive Control, and Spoiling). Each of the scales demonstrated strong internal consistency and was associated with concurrent measures of mothers' causal attributions about emotional responses to infant crying. Predictive validity to observed maternal sensitivity at 6 months and mother-reported infant behavioral problems at one year was demonstrated. The importance of a questionnaire method to assess parents' beliefs regarding infant crying in developmental research is discussed and future methodological directions are outlined.
Haltigan, John D.; Leerkes, Esther M.; Burney, Regan V.; Brien, Marion O'; Supple, Andrew J.; Calkins, Susan D.
Structural Stability for the Riccati Equation.
National Technical Information Service (NTIS)
A variant of the notion of structural stability of Thom is introduced for the Riccati equation. The author demonstrates a theorem which resolves structural stability for the Riccati equation, and gives a clearer picture of certain algebraic pathology of t...
R. S. Bucy
Factor Structure of the Dutch Version of the Childhood Trauma Questionnaire-SF among Female Sex Workers in the Netherlands
In this study, the factor structure of the Childhood Trauma Questionnaire short form (CTQ-SF) in a group of 123 female sex workers in the Netherlands was examined. Structural equation modeling was used to perform the confirmatory factor analysis. The fit between the five-factor model of Bernstein and Fink and the observed empirical model was good. We found a five-factor solution
Stefan Bogaerts; Annelies L. Daalder; Marinus Spreen; Leontien M. Van der Knaap; Jens Henrichs
Structural Equation Modeling of Multivariate Time Series
The covariance structure of a vector autoregressive process with moving average residuals (VARMA) is derived. It differs from other available expressions for the covariance function of a stationary VARMA process and is compatible with current structural equation methodology. Structural equation modeling programs, such as LISREL, may therefore be…
du Toit, Stephen H. C.; Browne, Michael W.
Reliability, Validity, and Factor Structure of the Creative Achievement Questionnaire
The Creative Achievement Questionnaire (CAQ) is a new self-report measure of creative achievement that assesses achievement across 10 do- mains of creativity. It was designed to be objective, em- pirically valid, and easy to administer and score. Study 1 established test-retest reliability (r = .81, p < .0001) and internal consistency reliability (? = .96) in a sam- ple of
Shelley Carson; Jordan Peterson; Daniel Higgins
Variational structure of the Vlasov equation
SciTech Connect
The variational structure of the Vlasov-Maxwell integral equations is derived for a plasma equilibrium having two ignorable coordinates. It is shown that the kernel of the Maxwell equations is a self-adjoint integral operator. This operator may also be represented as a differential equation of arbitrary order. This representation is useful when the differential operator is truncated to finite order, yielding a system of intrinsically self-adjoint differential equations.
Berk, H. L.; Dominguez, R. R.; Maschke, E. K.
A Norwegian adaptation of the Penn State Worry Questionnaire: factor structure, reliability, validity and norms.
A Norwegian version of the Penn State Worry Questionnaire (PSWQ) was administered to 304 undergraduate students together with the Beck Depression Inventory (BDI), the State-Trait Anxiety Inventory (STAI) and the Maudsley Obsessive Compulsive Inventory (MOCI). The PSWQ was also administered to a community sample comprising 879 subjects, together with the Beck Anxiety Inventory (BAI), the Beck Depression Inventory II (BDI II) and the White Bear Suppression Inventory (WBSI). Structural equation modeling showed that a three-factor solution of the PSWQ gave the best goodness of fit. The Norwegian version of the PSWQ demonstrated adequate psychometric properties in terms of reliability and validity in both samples. Females scored higher than males on PSWQ. PMID:16869861
Pallesen, Stĺle; Nordhus, Inger Hilde; Carlstedt, Berit; Thayer, Julian F; Johnsen, Tom Backer
Factor Structure and Psychometric Properties of the Young Schema Questionnaire (Short Form) in Chinese Undergraduate Students
This study investigated cross-cultural differences in the factor structure and psychometric properties of the Young Schema Questionnaire (short form; YSQ-SF). The participants were 712 Chinese undergraduate students. The total sample was randomly divided into two sub-samples. Exploratory Factor Analysis (EFA) was conducted on questionnaire results…
Cui, Lixia; Lin, Wenwen; Oei, Tian P. S.
A matrix Riccati equation is considered with respect to changes in the phase portrait induced by continuously differential deformations of the coefficient matrices. Necessary and sufficient conditions are given which characterize structural stability of a...
Hamiltonian structures and Lax equations
We show that any hamiltonian system, which is integrable in the sense of Liouville, admits a Lax representation, at least locally at generic points in phase space. We introduce the most general Poisson bracket ensuring the involution property of the integrals of motion and existence of a Lax pair. We give examples of the structure we describe.
O. Babelon; C.-M. Viallet
Structural Analysis of the Resident Assistant Cultural Diversity Questionnaire
This study investigated the five-factor structure of the Resident Assistant Cultural Diversity (RACD) instrument, which assesses resident assistant (RA) confidence in addressing issues of cultural diversity in college and university residence halls. The instrument has five components that explore RA confidence: (1) belief in the need for cultural…
Johnson, Vanessa D.; Kang, Young-Shin; Thompson, George F.
Testing Structural Invariance of the Achievement Goal Questionnaire in American, Chinese, and Dutch College Students
This study investigates the structural invariance of the Achievement Goal Questionnaire (AGQ) in American, Chinese, and Dutch college students. Using confirmatory factor analyses (CFA), the authors found evidence for the four-factor structure of achievement goals in all three samples. Subsequent multigroup CFAs supported structural invariance of…
Sun, Huaping; Hernandez, Diley
This study investigated cross-cultural differences in the factor structure and psychometric properties of the Young Schema\\u000a Questionnaire (short form; YSQ-SF). The participants were 712 Chinese undergraduate students. The total sample was randomly\\u000a divided into two sub-samples. Exploratory Factor Analysis (EFA) was conducted on questionnaire results for Group A, and Confirmatory\\u000a Factor Analysis (CFA) was conducted on Group B. Multiple regression
Lixia Cui; Wenwen Lin; Tian P. S. Oei
The Abridged Dutch Metamemory in Adulthood (MIA) Questionnaire: Structure and Effects of Age, Sex, and Education
This study presents data on the factor structure, reliability, and discriminant validity of the Metamemory in Adulthood (MIA) questionnaire in a Dutch sample of 1, 899 normal and healthy participants aged 24 to 86 years. The factor structure of the Dutch MIA corresponded with that of the original MIA. The Strategy scale could be divided into two subscales: External and
Rudolf W. H. M. Ponds; Jellemer Jolles
Composite Reliability in Structural Equations Modeling.
The potential for bias in reliability estimation and for errors in item selection when alpha or unit-weighted omega coefficients are used is explored under simulated conditions. Results suggest that composite reliability may be an assessment tool but should not be an item selection tool in structural equations. (SLD)
Bacon, Donald R.; And Others
Structural Equation Modeling in Behavioral Research
April 27, 2012 10:00 AM - 11:00 AM + Add to Outlook Calendar Date and Time: Friday, April 27th, 10:00-11:00am, EPS/7107 Lecturer: Natalia Frishman, MD PhD Candidate Iowa State University Print This Page Structural Equation Modeling in Behavioral Research News
Structural Equation Modeling in Rehabilitation Counseling Research
Structural equation modeling (SEM) has become increasingly popular in counseling, psychology, and rehabilitation research. The purpose of this article is to provide an overview of the basic concepts and applications of SEM in rehabilitation counseling research using the AMOS statistical software program.
Chan, Fong; Lee, Gloria K.; Lee, Eun-Jeong; Kubota, Coleen; Allen, Chase A.
Multiplicity Control in Structural Equation Modeling
Researchers conducting structural equation modeling analyses rarely, if ever, control for the inflated probability of Type I errors when evaluating the statistical significance of multiple parameters in a model. In this study, the Type I error control, power and true model rates of famsilywise and false discovery rate controlling procedures were…
Cribbie, Robert A.
Prolongation structures of nonlinear evolution equations. II
The prolongation structure of a closed ideal of exterior differential forms is further discussed, and its use illustrated by application to an ideal (in six dimensions) representing the cubically nonlinear Schroedinger equation. The prolongation structure in this case is explicitly given, and recurrence relations derived which support the conjecture that the structure is open - i.e., does not terminate as a set of structure relations of a finite-dimensional Lie group. We introduce the use of multiple pseudopotentials to generate multiple Baecklund transformation, and derive the double Baecklund transformation. This symmetric transformation concisely expresses the (usually conjectured) theorem of permutability, which must consequently apply to all solutions irrespective of asymptotic constraints.
Estabrook, F. B.; Wahlquist, H. D.
Determinants of capital structure choice: A structural equation modeling approach
In their seminal research on the determinants of capital structure choice using structural equation modeling (SEM), Titman and Wessels [Titman, S., & Wessels, R. (1988). The determinants of capital structure choice. Journal of Finance, 43, 1–19] obtain weak results and hence call for further investigation. We apply a Multiple Indicators and Multiple Causes (MIMIC) model, with refined indicators, to a
Chingfu Chang; Alice C. Lee; Cheng F. Lee
Use of a safety climate questionnaire in UK health care: factor structure, reliability and usability
Aim To explore the factor structure, reliability, and potential usefulness of a patient safety climate questionnaire in UK health care. Setting Four acute hospital trusts and nine primary care trusts in England. Methods The questionnaire used was the 27 item Teamwork and Safety Climate Survey. Thirty three healthcare staff commented on the wording and relevance. The questionnaire was then sent to 3650 staff within the 13 NHS trusts, seeking to achieve at least 600 responses as the basis for the factor analysis. 1307 questionnaires were returned (36% response). Factor analyses and reliability analyses were carried out on 897 responses from staff involved in direct patient care, to explore how consistently the questions measured the underlying constructs of safety climate and teamwork. Results Some questionnaire items related to multiple factors or did not relate strongly to any factor. Five items were discarded. Two teamwork factors were derived from the remaining 11 teamwork items and three safety climate factors were derived from the remaining 11 safety items. Internal consistency reliabilities were satisfactory to good (Cronbach's alpha ?0.69 for all five factors). Conclusions This is one of the few studies to undertake a detailed evaluation of a patient safety climate questionnaire in UK health care and possibly the first to do so in primary as well as secondary care. The results indicate that a 22 item version of this safety climate questionnaire is useable as a research instrument in both settings, but also demonstrates a more general need for thorough validation of safety climate questionnaires before widespread usage.
Hutchinson, A; Cooper, K L; Dean, J E; McIntosh, A; Patterson, M; Stride, C B; Laurence, B E; Smith, C M
Bayesian Structural Equations Modeling for Ordinal Response Data with Missing Responses and Missing Covariates
Structural equations models (SEMs) have been extensively used to model survey data arising in the fields of sociology, psychology, health, and economics with increasing applications where self assessment questionnaires are the means to collect the data. We propose the SEM for multilevel ordinal response data from a large multilevel survey conducted by the US Veterans Health Administration (VHA). The proposed
Sungduk Kim; Sonali Das; Ming-Hui Chen; Nicholas Warren
Temperament factor structure in fragile X syndrome: the Children's Behavior Questionnaire.
Early patterns of temperament lay the foundation for a variety of developmental constructs such as self-regulation, psychopathology, and resilience. Children with fragile X syndrome (FXS) display unique patterns of temperament compared to age-matched clinical and non-clinical samples, and early patterns of temperament have been associated with later anxiety in this population. Despite these unique patterns in FXS and recent reports of atypical factor structure of temperament questionnaires in Williams Syndrome (Leyfer, John, Woodruff-Borden, & Mervis, 2012), no studies have examined the latent factor structure of temperament scales in FXS to ensure measurement validity in this sample. The present study used confirmatory factor analysis to examine the factor structure of a well-validated parent-reported temperament questionnaire, the Children's Behavior Questionnaire (Rothbart, Ahadi, Hershey, & Fisher, 2001), in a sample of 90 males with FXS ages 3-9 years. Our data produced a similar, but not identical, three-factor model that retained the original CBQ factors of negative affectivity, effortful control, and extraversion/surgency. In particular, our FXS sample demonstrated stronger factor loadings for fear and shyness than previously reported loadings in non-clinical samples, consistent with reports of poor social approach and elevated anxiety in this population. Although the original factor structure of the Children's Behavior Questionnaire is largely retained in children with FXS, differences in factor loading magnitudes may reflect phenotypic characteristics of the syndrome. These findings may inform future developmental and translational research efforts. PMID:24380785
Roberts, Jane E; Tonnsen, Bridgette L; Robinson, Marissa; McQuillin, Samuel D; Hatton, Deborah D
The reassurance questionnaire: Comparison of the latent structure in university, community, and medical samples
The Reassurance Questionnaire (RQ; Speckens, Spinhoven, Van Hemert, & Bolk, (2000) is a self-report measure designed to assess the extent to which patients feel reassured by their attending physicians. While the original RQ was validated in Dutch, the invariance of the factor structure has not been examined in the English version of the RQ. In the current study, the English
Nicole E. Pugh; Heather D. Hadjistavropoulos; Donald Sharpe
The Factorial Structure of the Expectations about Counseling Questionnaire-Brief Form: Some Serious Questions.
Examines responses of Americans and Icelanders to the Expectations About Counseling Questionnaire-Brief Form (EAC-B) through confirmatory factor analyses. Investigates the validity of and expresses concern for the underlying factor structure of the EAC-B. Argues that a four-factor solution for the EAC-B is too complex and does not fit the student…
Aegisdottir, Stefania; Gerstein, Lawrence H.; Gridley, Betty E.
The Factor Structure and Dimensional Scoring of the Generalized Anxiety Disorder Questionnaire for "DSM-IV"
Despite favorable psychometric properties, the Generalized Anxiety Disorder Questionnaire for the "Diagnostic and Statistical Manual of Mental Disorders" (4th ed.) (GAD-Q-IV) does not have a known factor structure, which calls into question use of its original weighted scoring system (usually referred to as the dimensional score). Analyses…
Rodebaugh, Thomas L.; Holaway, Robert M.; Heimberg, Richard G.
Cascade structure for equation error minimization
There are several obstacles which must be overcome before IIR adaptive algorithms will be practical for real time signal processing applications. Two primary concerns are stability and potentially multi-modal performance surfaces. In this paper, an adaptive algorithm which addresses both of these problems is introduced. Using the equation error structure, an IIR adaptive transfer function is obtained. The polynomial which generates system poles is realized as a series of second order sections in cascade. The performance of this algorithm is compared to that of other IIR adaptive structures.
David, R.A.
Musculoskeletal pain illness perceptions: Factor structure of the Illness Perceptions Questionnaire-Revised
Background: The Revised Illness Perceptions Questionnaire (IPQ-R) is commonly used to measure illness perceptions. We tested whether the structure of the IPQ-R was appropriate for use with primary care musculoskeletal pain patients.Methods: Confirmatory (C) and exploratory (E) factor analyses (FA) were used to test whether the structure of the IPQ-R was supported for patients with knee pain (n?=?393), hand pain
Elaine E. Nicholls; Susan Hill; Nadine E. Foster
Effect of questionnaire structure on recall of drug utilization in a population of university students
Background Self-reported data are a common source of information about drug exposure. Modes of data collection differ considerably and the questionnaire's structure may affect prevalence estimates. We compared the recall of medication use evaluated by means of two questionnaires differing in structure and length. Methods Drug utilization was assessed by two alternative versions of a questionnaire (A – 4 pages, including specific questions for 12 indications/pharmacological groups and one question for "other medicines"; B – 1 page, including 1 open-ended question to cover overall drug consumption). Each of 32 classes in a private University in Maputo, Mozambique, was randomly assigned questionnaire A (233 participants) or B (276 participants). Logistic regression (allowing for clustering by classroom) was used to compare the two groups in terms of socio-demographic characteristics and medication used during the previous month. Results Overall, 67.4% of the subjects had used at least one drug during the previous month. The following prevalences were greater among participants completing questionnaire A: use of drugs from two or more pharmacological groups (60.5% vs. 34.4%, p < 0.001), use of two or more drugs (66.2% vs. 43.0%, p < 0.001), and use of antibiotics (14.6% vs. 6.9%, p = 0.001), antifungals (9.4% vs. 4.0%, p = 0.013), antiparasitics (5.6% vs. 1.8%, p = 0.031) and antacids (8.6% vs. 3.6%, p = 0.024). Information about duration of treatment and medical advice was more complete with version A. Conclusion The indication/drug-specific questions (questionnaire A) revealed a significantly higher prevalence of use of medicines – antibiotics, antifungals, antiparasitics and antacids – without compromising the completeness of the information.
Factor structure of the Minnesota Satisfaction Questionnaire short form for restaurant employees.
The factor structure of the Minnesota Satisfaction Questionnaire short form for nonsupervisory restaurant employees was explored in questions among 2000 employees of three full-service restaurant chains operating in midwestern United States. A total of 2000 surveys were distributed to hourly employees of the three chains. From the mailing, 924 surveys were returned and found useable, a 46.2% response rate. Principal factors analysis identified a four-factor structure for the employees, in contrast to the original two-factor structure, but as in other studies the structure was multifactorial. PMID:15077790
Hancer, Mura; George, R Thomas
The Smoluchowski diffusion equation for structured macromolecules near structured surfaces
NASA Astrophysics Data System (ADS)
Beginning with the molecular-based Fokker-Planck equation obtained previously [M. H. Peters, J. Chem. Phys. 110, 528 (1999); J. Stat. Phys. 94, 557 (1999)], the Smoluchowski diffusion equation is derived here to describe the spatial and orientational dynamics of molecularly structured macromolecules near molecularly structured surfaces. The formal scaling and perturbation methods employed allow the establishment of definite limits on the use of the Smoluchowski equation when surfaces are present. It is shown that the Smoluchowski equation reduces to that given previously [D. W. Condiff and J. S. Dahler, J. Chem. Phys. 44, 3988 (1966)] in the absence of external surfaces. A specific example application is given involving a spherical macromolecule with electrostatic charge segments near a planar surface with an arbitrary charge distribution. Finally, we show that the short-time solution to the Smoluchowski equation obtained here yields a Brownian dynamics method consistent with that given previously [E. Dickinson, S. A. Allison, and J. A. McCammon, J. Chem. Soc. Faraday Trans. 2 81, 591 (1985)] for orientable, interacting Brownian particles. This study has applications to problems involving site-specific adsorption of orientable, structured Brownian particles, such as association or adsorption of biological macromolecules to cellular surfaces and enzyme-substrate docking kinetics, to name a few.
Peters, Michael H.
Factor structure of the Singapore English version of the KINDL® children quality of life questionnaire
BACKGROUND: Quality of life (QoL) outcomes are useful in the assessment of physical, mental and social well-being and for informed healthcare decision making. However, few studies have evaluated QoL issues among Asian children due largely to the lack of culturally valid and reliable QoL questionnaires. Hence, we aimed to report the psychometric properties, in particular factor structure, of KINDL (Singapore)
Hwee-Lin Wee; Ulrike Ravens-Sieberer; Michael Erhart; Shu-Chuen Li
The Parent-Form Child Health Questionnaire in Australia: Comparison of Reliability, Validity, Structure, and Norms
Objective: To improve the ability to describe and compare child health within and between countries, using standardized multidimensional child health measures. Methods: Data on population-specific psychometrics, the measurement structure, and norms are a vital pre- requisite. These properties for the Child Health Questionnaire (CHQ) were examined for an Australian popu- lation and compared with the originating U.S. data. The CHQ50-item
Elizabeth Waters; Louisa Salmon; Melissa Wake
Testing the structural and cross-cultural validity of the KIDSCREEN-27 quality of life questionnaire
Objectives The aim of this study is to assess the structural and cross-cultural validity of the KIDSCREEN-27 questionnaire.\\u000a \\u000a \\u000a \\u000a Methods The 27-item version of the KIDSCREEN instrument was derived from a longer 52-item version and was administered to young people\\u000a aged 8–18 years in 13 European countries in a cross-sectional survey. Structural and cross-cultural validity were tested using\\u000a multitrait multi-item analysis, exploratory and confirmatory
Stephane Robitail; Ulrike Ravens-Sieberer; Marie-Claude Simeoni; Luis Rajmil; Jeanet Bruil; Mick Power; Wolfgang Duer; Bernhard Cloetta; Ladislav Czemy; Joanna Mazur; Agnes Czimbalmos; Yannis Tountas; Curt Hagquist; Jean Kilroe; Pascal Auquier
School Motivation Questionnaire for the Portuguese population: structure and psychometric studies.
It is presented the structure and psychometric studies of the "School Motivation Questionnaire". The SMQ is a self-report questionnaire with 101 items, organized in sixteen scales that measure the students' goal orientations, the perceived classroom goal structures, the perceived teacher's autonomy support and the use of learning strategies. Twelve scales are adapted from the "Learning Climate Questionnaire", "Perceptions of Instrumentality" and "Cuestionário a Estudiantes". Four scales and five additional items are created new. The psychometric studies rely on a convenience sample consisting of 9th and 12th grade students (N = 485) of Portuguese schools. The factorial and construct validity, verified through several exploratory factorial analyses to the data, presents a final solution of six factors, labelled Strategies (F1), Teacher Extrinsic Goals (F2), Student Extrinsic Goals, Externally Regulated (F3) Teacher Intrinsic Goals (F4), Student Extrinsic Goals, Internally Regulated (F5), and Student Intrinsic Goals (F6). The six-factor solution explains a significant variance of the scale results (53.95%). Good coefficients of internal consistency are obtained for all factors, never below (.858; F6). In sum there is strong evidence to support the multi-dimensionality of SMQ, upholding that the data obtained is exploratory and applies for future validation studies. PMID:23156946
Cordeiro, Pedro Miguel Gomes; Figueira, Ana Paula Couceiro; da Silva, José Tomás; Matos, Lennia
An Atmospheric Structure Equation for Grain Growth
We present a method to include the evolution of the grain size and grain opacity ?gr in the equations describing the structure of protoplanetary atmospheres. The key assumption of this method is that a single grain size dominates the grain size distribution at any height r. In addition to following grain growth, the method accounts for mass deposition by planetesimals and grain porosity. We illustrate this method by computation of a simplified atmosphere structure model. In agreement with previous works, grain coagulation is seen to be very efficient. The opacity drops to values much below the often-used "interstellar medium opacities" (~1 cm2 g–1) and the atmosphere structure profiles for temperature and density resemble that of the grain-free case. Deposition of planetesimals in the radiative part of the atmosphere hardly influences this outcome as the added surface is quickly coagulated away. We observe a modest dependence on the internal structure (porosity), but show that filling factors cannot become too large because of compression by gas drag.
Ormel, C. W.
Structural equation modeling of approval voting data.
The method of approval voting is a commonly used voting procedure in which each judge selects a subset of the alternatives. By postulating that the random utilities associated with the choice options in approval voting elections follow a multivariate normal distribution under the Thurstonian framework, Regenwetter, Ho, and Tsetlin (2007) attempted to integrate the normative theories and individual variabilities in modeling social behavior. However, their approach is limited to only three alternatives, due to computational intractability as the number of alternatives increases. In this article, we reparameterize extensions of their models under the structural equation modeling framework and propose the use of limited information methods for estimating model parameters. As a result, we are able to extend their previous approach to the analysis of approval voting data with any number of alternatives. Two applications are presented to illustrate the usefulness of such an approach. PMID:20805603
Tsai, Rung-Ching
Background: The Revised Illness Perceptions Questionnaire (IPQ-R) is commonly used to measure illness perceptions. We tested whether the structure of the IPQ-R was appropriate for use with primary care musculoskeletal pain patients. Methods: Confirmatory (C) and exploratory (E) factor analyses (FA) were used to test whether the structure of the IPQ-R was supported for patients with knee pain (n = 393), hand pain (n = 2113) and back pain (n = 1591). CFA was used to test whether the timeline acute/chronic, timeline cyclical, consequences, personal control, treatment control, illness coherence and emotional representation dimensions of the IPQ-R were distinct; EFA was used to explore potential structure for patients' views on the cause of their condition. Results: Goodness-of-fit indices for the CFA were below our criteria for good model fit. Removal of six items from the model improved model fit, but our criteria for good model fit was still not achieved. An interpretable factor solution could not be determined for the causal items on the questionnaire. Conclusions: Our data show limited evidence that the seven dimensions of the IPQ-R are distinct. A clear structure for the causal items was not determined. Further work is needed to develop the IPQ-R for use with primary care musculoskeletal pain patients.
Nicholls, Elaine E.; Hill, Susan; Foster, Nadine E.
Measuring Integrated Socioemotional Guidance at School: Factor Structure and Reliability of the Socioemotional Guidance Questionnaire (SEG-Q)
Socioemotional guidance of students has recently become an integral part of education, however no instrument exists to measure integrated socioemotional guidance. This study therefore examines the factor structure and reliability of the Socioemotional Guidance Questionnaire. Psychometric properties of the Socioemotional Guidance Questionnaire and…
Jacobs, Karen; Struyf, Elke
Does the level of expressed emotion (LEE) questionnaire have the same factor structure for adolescents as it has for adults?
Background The level of expressed emotion (LEE) is a four-factor questionnaire that measures expressed emotion (EE) as perceived by the recipient. These factors are: perceived lack of emotional support, perceived intrusiveness, perceived irritation, and perceive criticism. The four factors of the LEE has previously been found to be related to psychological disorders and has good psychometric properties for adults. However, it has not previously been studied in adolescent populations. Methods A total of 311 adolescents participated in this study. Using structural equation modeling, confirmatory factor analyses were conducted to examine if the LEE also had the same four-factor structure for adolescents as it does for adults. Results The confirmatory factor analyses demonstrated that the LEE's four-factor structure also applied to adolescents. The internal consistency of the scales were good and all the inter-correlations between the scales were significant. Additionally, the factors were significantly correlated to adolescent depressive and anxiety symptom score dimensions. Conclusion These findings seem to indicate that the LEE may be a good instrument in the measurement of adolescents perceived EE.
Raaijmakers, Quinten A. W.; Gerlsma, Coby; Meeus, Wim
A Framework for Structural Equation Models in General Pedigrees
Background\\/Aims: Structural Equation Modeling (SEM) is an analysis approach that accounts for both the causal relationships between variables and the errors associated with the measurement of these variables. In this paper, a framework for implementing structural equation models (SEMs) in family data is proposed. Methods: This framework includes both a latent measurement model and a structural model with covariates. It
Nathan J. Morris; Robert C. Elston; Catherine M. Stein
Learning Structural Equation Models for fMRI
Structural equation models can be seen as an extension of Gaussian belief net- works to cyclic graphs, and we show they can be understood generatively as the model for the joint distribution of long term average equilibrium activity of Gaus- sian dynamic belief networks. Most use of structural equation models in fMRI involves postulating a particular structure and comparing learnt
Amos J. Storkey; Enrico Simonotto; Heather Whalley; Stephen Lawrie; Lawrence Murray; David Mcgonigle
Use of structural equation modeling in counseling psychology research
Structural equation modeling (multivariate analysis with latent variables, also called causal modeling or covariance structure analysis) is a valuable methodological tool for use in counseling psychology research. Essentially the broad framework that subsumes many well-known proce- dures (e.g., multiple linear regression, factor analysis, path analysis), structural equation modeling allows for analysis of causal patterns among unobserved variables represented by multiple
Ruth E. Fassinger
Development and factor structure of the Baby Eating Behaviour Questionnaire in the Gemini birth cohort.
The objective of this study was to develop a parent-report psychometric measure of infant appetite during the period of exclusive milk-feeding. Constructs and items for the Baby Eating Behaviour Questionnaire (BEBQ) were derived from an existing psychometric measure validated for older ages, the Children's Eating Behaviour Questionnaire, supplemented by a review of the literature on milk-feeding behaviours. Cognitive interviewing with a sample of mothers (n=10) was used to refine the questions. The factor structure of the 18-item BEBQ was assessed in infants (one per family) from the Gemini twin birth cohort (n=2402 families). Principal Component Analysis identified four distinct appetitive constructs, all of which had good internal reliability: 'enjoyment of food' (Cronbach's ?=0.81), 'food responsiveness' (?=0.79), 'slowness in eating' (?=0.76), and 'satiety responsiveness' (?=0.73). A single item assessing 'general appetite' correlated with all of the constructs. The BEBQ is the first standardised measure of infant appetite designed to characterise appetitive traits that might confer susceptibility to excess weight gain. PMID:21672566
Llewellyn, Clare H; van Jaarsveld, Cornelia H M; Johnson, Laura; Carnell, Susan; Wardle, Jane
The Big Five Personality Traits and Uses of Music: A Replication in Malaysia Using Structural Equation Modeling
The current study set out to replicate and extend a recent paper (Chamorro-Premuzic & Furnham, 2007) on personality and uses of music using structural equation modeling. Responses to questionnaire data from 227 Malaysian university students showed that, in line with our hypotheses, individuals higher in Neuroticism were more likely to use music for emotional regulation (influencing their mood states), Extraversion
Tomas Chamorro-Premuzic; Viren Swami; Adrian Furnham; Ismail Maakip
A structural equation model of depression and the defense system factors: A survey among Chinese college students
Questionnaires were administered to a large sample of subjects (1363 Chinese college students), to evaluate the mediating risk factors in the defense system of depression, including personality, coping skills, interpersonal context and family environment. Structural equation modeling (SEM) was used to analyze a total of 12 variables in order to understand how they interact with each other. Eysenck's Neuroticism, Extraversion,
Jue Jin; Yi-Yuan Tang; Yinghua Ma; Shipin Lv; Ying Bai; Hangli Zhang
Shock wave structure for generalized Burnett equations
Stationary shock wave solutions for the generalized Burnett equations (GBE) [A. V. Bobylev, ``Generalized Burnett hydrodynamics,'' J. Stat. Phys. 132, 569 (2008)] are studied. Based on the results of Bisi et al. [``Qualitative analysis of the generalized Burnett equations and applications to half-space problems,'' Kinet. Relat. Models 1, 295 (2008)], we choose a unique (optimal) form of GBE and solve numerically the shock wave problem for various Mach numbers. The results are compared with the numerical solutions of Navier-Stokes equations and with the Mott-Smith approximation for the Boltzmann equation (all calculations are done for Maxwell molecules) since it is believed that the Mott-Smith approximation yields better results for strong shocks. The comparison shows that GBE yield certain improvement of the Navier-Stokes results for moderate Mach numbers.
Bobylev, A. V.; Bisi, M.; Cassinari, M. P.; Spiga, G.
Eating Disorder Examination-Questionnaire Factor Structure and Construct Validity In Bariatric Surgery Candidates
Objective The Eating Disorder Examination-Questionnaire (EDE-Q) is increasingly used in studies with bariatric surgery patients although little is known about psychometric properties of this self-report measure in this clinical group. The current study evaluated the factor structure and construct validity of the EDE-Q in bariatric surgery candidates. Methods Participants were a consecutive series of 174 obese bariatric surgery candidates who completed the EDE-Q and a battery of behavioral and psychological measures. Results Confirmatory factor analysis (CFA) revealed an inadequate fit for the original EDE-Q structure but revealed a good fit for an alternative structure suggested by recent research with obese samples. CFA supported a 7-item, 3-factor structure; the three factors were interpreted as dietary restraint, shape/weight overvaluation, and body dissatisfaction. The three factors converged with other relevant collateral measures. Conclusions These factor analytic findings, which replicate recent findings from studies with diverse obese samples, demonstrated convergent validity. Implications of these findings for clinical assessment and research with bariatric surgery patients are discussed.
Grilo, Carlos M.; Henderson, Kathryn E.; Bell, Robert L.; Crosby, Ross D.
Factor Structure of the Children's Behavior Questionnaire in Children with Williams Syndrome
To examine the factor structure of temperament in 5 – 10-year-olds with Williams syndrome (WS), an exploratory factor analysis was conducted on the responses of parents of 192 children on the Children's Behavior Questionnaire (CBQ). Four factors were identified. Two corresponded to factors reported for typically developing children: Effortful Control and Extraversion/Surgency and two corresponded to the temperament constructs of withdrawal/inhibition and irritability/frustration and activity, observed in typically-developing infants. Parents of 109 of the 192 participants also completed the Anxiety Disorders Interview Schedule, Parent version. Children with an anxiety disorder other than specific phobia differed significantly from children without an anxiety disorder on all factors except Extraversion/Surgency. Children with ADHD differed significantly from children without ADHD on Effortful Control and Extraversion/Surgency.
Leyfer, Ovsanna; John, Angela E.; Woodruff-Borden, Janet; Mervis, Carolyn B.
Goodness of Fit Criteria in Structural Equation Models.
Several goodness of fit (GOF) criteria have been developed to assist the researcher in interpreting structural equation models. However, the determination of GOF for structural equation models is not as straightforward as that for other statistical approaches in multivariate procedures. The four GOF criteria used across the commonly used…
Schumacker, Randall E.
Fitting Multivariate Normal Finite Mixtures Subject to Structural Equation Modeling.
Discusses fitting multivariate normal mixture distributions to structural equation modeling. The model used is a LISREL submodel that includes confirmatory factor and structural equation models. Two approaches to maximum likelihood estimation are used. A simulation study compares confidence intervals based on the observed information and…
Dolan, Conor V.; van der Maas, Han L. J.
Fitting arma time series by structural equation models
This paper outlines how the stationary ARMA (p, q) model can be specified as a structural equations model. Maximum likelihood estimates for the parameters in the ARMA model can be obtained by software for fitting structural equation models. For pure AR and mixed ARMA models, these estimates are approximately unbiased, while the efficiency is as good as those of specialized
Stef van Buuren; TNO PREVENTION
Fitting ARMA Time Series by Structural Equation Models.
This paper outlines how the stationary ARMA (p,q) model (G. Box and G. Jenkins, 1976) can be specified as a structural equation model. Maximum likelihood estimates for the parameters in the ARMA model can be obtained by software for fitting structural equation models. The method is applied to three problem types. (SLD)
van Buuren, Stef
Two Rules of Identification for Structural Equation Models
Identification of structural equation models remains a challenge to many researchers. Although empirical tests of identification are readily available in structural equation modeling software, these examine local identification and rely on sample estimates of parameters. Rules of identification are available, but do not include all models…
Bollen, Kenneth A.; Davis, Walter R.
Sensitivity of rocky planet structures to the equation of state
Structures were calculated for Mercury, Venus, Earth, the Moon, and Mars, using a core-mantle model and adjusting the core radius to reproduce the observed mass and diameter of each body. Structures were calculated using Fe and basalt equations of state of different degrees of sophistication for the core and mantle. The choice of equation of state had a significant effect on the inferred structure. For each structure, the moment of inertia ratio was calculated and compared with observed values. Linear Grueneisen equations of state fitted to limited portions of shock data reproduced the observed moments of inertia significantly better than did more detailed equations of state incorporating phase transitions, presumably reflecting the actual compositions of the bodies. The linear Grueneisen equations of state and corresponding structures seem however to be a reasonable starting point for comparative simulations of large-scale astrophysical impacts.
Swift, D C
Validating the Children's Behavior Questionnaire in Dutch Children: Psychometric Properties and a Cross-Cultural Comparison of Factor Structures
In this article, we examined the factorial validity of the Dutch translation of the Children's Behavior Questionnaire (CBQ) and the Very Short Form scores. In addition, we conducted cross-cultural comparisons of temperament structure. In total, 353 parents of 6- to 8-year-olds completed the instrument. The original higher order factor structure of…
Sleddens, Ester F. C.; Kremers, Stef P. J.; Candel, Math J. J. M.; De Vries, Nanne N. K.; Thijs, Carel
Factor Structure of a Brief Version of the Ways of Coping (WOC) Questionnaire: A Study with Veterinary Medicine Students.
Explored structure of brief version of Ways of Coping (WOC) Questionnaire and coping strategies employed by students enrolled in stressful academic programs. Findings from 207 veterinary medicine students lend support to view that there are relatively stable underlying coping structures across samples or groups within specified coping situations.…
Brown, Sharon L.
Examining the Structural Validity of the Strengths and Difficulties Questionnaire (SDQ) in a U.S. Sample of Custodial Grandmothers
The authors examined the structural validity of the parent informant version of the Strengths and Difficulties Questionnaire (SDQ) with a sample of 733 custodial grandparents. Three models of the SDQ's factor structure were evaluated with confirmatory factor analysis based on the item covariance matrix. Although indices of fit were good across all…
Palmieri, Patrick A.; Smith, Gregory C.
Phenotypic, Genetic, and Nonshared Environmental Parallels in the Structure of Personality: A View From the Multidimensional Personality Questionnaire
How closely do observed, phenotypic personality structures correspond with underlying, genetic, and environmental personality structures? This question was addressed using data from 2,490 pairs of twins from the Minnesota Twin Registry, who completed A. Tellegen's (1982) Multidimensional Personality Questionnaire (MPQ). Phenotypic, additive genetic, and nonshared environmental correlations were computed among the MPQ's eleven primary scales. Principal component analyses of all
Robert F. Krueger
Dysfunctional Cognitions in Personality Pathology: The Structure and Validity of the Personality Belief Questionnaire
Background This study examines the structure of the Personality Belief Questionnaire (PBQ), a self-report instrument designed to assess dysfunctional beliefs associated with personality pathology, as proposed by the cognitive theory of personality dysfunction. Methods The PBQ was examined using exploratory factor analysis with responses from 438 depressed outpatients, and confirmatory factor analysis with responses from 683 treatment-seeking psychiatric outpatients. All participants were assessed for personality disorder using a standard clinical interview. The validity of the resulting factor structure was assessed in the combined sample (N=1121) by examining PBQ scores for patients with and without personality disorder diagnoses. Results Exploratory and confirmatory analyses converged to indicate that the PBQ is best described by 7 empirically identified factors: 6 assess dysfunctional beliefs associated with forms of personality pathology recognized in DSM-IV. Validity analyses revealed that those diagnosed with a personality disorder evidenced a higher average score on all factors, relative to those without these disorders. Subsets of patients diagnosed with specific DSM-IV personality disorders scored higher, on average, on the factor associated with their respective diagnosis, relative to all other factors. Conclusions The pattern of results has implications for the conceptualization of personality pathology. To our knowledge, no formal diagnostic or assessment system has yet systematically incorporated the role of dysfunctional beliefs into its description of personality pathology. The identification of dysfunctional beliefs may not only aid in case conceptualization, but may provide unique targets for psychological treatment. Recommendations for future personality pathology assessment systems are provided.
Fournier, Jay C.; DeRubeis, Robert J.; Beck, Aaron T.
Modeling Attitude toward Statistics by a Structural Equation
In this study, we examined whether the constructs of usefulness, motivation, likeness, confidence, and anxiety influence the student's attitude towards statistics. Two hundred ninety eight students enrolled in the private university were surveyed by using the questionnaire proposed by Auzmendi (1992). Data analysis was done by structural…
Escalera-Chávez, Milka Elena; García-Santillán, Arturo; Venegas-Martínez, Francisco
The Preschool Behaviour Questionnaire: Stability of its Factor Structure Between Cultures, Sexes, Ages and Socioeconomic Classes
The Preschool Behaviour Questionnaire has been widely used in North-America to study social competencies and behavioural problems of preschool children. The 30 item rating scale was created by Behar and Stringfield (1974) as an adaptation of Rutter's (1967) Children's Behaviour Questionnaire intended for elementary school children. In their original study Behar and Stringfield proposed a three-component solution for their data:
R. E. Tremblay; L. Desmarais-Gervais; C. Gagnon; P. Charlebois
Parental feeding styles and adolescents' healthy eating habits. Structure and correlates of a Costa Rican questionnaire
This study designed and validated a questionnaire aimed at examining parental feeding styles to encourage healthy eating habits among Costa Rican adolescents. Adolescents (n=133; mean age 15.4 years), and their parents, participated in the study. The parents completed a parental feeding style questionnaire, and the adolescents completed 3-day food records. Confirmatory factor analyses suggest four distinct parental feeding styles, (a)
Rafael Monge-Rojas; Vanesa Smith-Castro; Uriyoán Colon-Ramos; Carlos Garita-Arce; Marta Sánchez-López; Anne Chinnock
Examining the factor structures of the Five Facet Mindfulness Questionnaire and the Self-Compassion Scale.
The Five Facet Mindfulness Questionnaire (FFMQ; Baer, Smith, Hopkins, Krietemeyer, & Toney, 2006) and the Self-Compassion Scale (SCS; Neff, 2003) are widely used measures of mindfulness and self-compassion in mindfulness-based intervention research. The psychometric properties of the FFMQ and the SCS need to be independently replicated in community samples and relevant clinical samples to support their use. Our primary aim was to establish the factor structures of the FFMQ and SCS in individuals with recurrent depression in remission, since Mindfulness-Based Cognitive Therapy (MBCT) was developed as a treatment for preventing depressive relapse. In order to determine the consistency across populations, we examined the factor structures of the FFMQ and SCS in 3 samples: (1) a convenience sample of adults, (2) a sample of adults who practice meditation, and (3) a sample of adults who suffer from recurrent depression and were recruited to take part in a trial of MBCT. Confirmatory factor analyses (CFAs) showed that a 4-factor hierarchical model of the FFMQ best fits the community sample and the clinical sample but that a 5-factor hierarchical model of the FFMQ best fits the meditator sample. CFA did not endorse the SCS 6-factor hierarchical structure in any of the 3 samples. Clinicians and researchers should be aware of the psychometric properties of the FFMQ to measure mindfulness when comparing meditators and nonmeditators. Further research is needed to develop a more psychometrically robust measure of self-compassion. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24490681
Williams, Matthew J; Dalgleish, Tim; Karl, Anke; Kuyken, Willem
Integrable structures for a generalized Monge-Ampčre equation
We consider a third-order generalized Monge-Ampčre equation uyyy - u{xxy/ 2 } + uxxxuxyy = 0, which is closely related to the associativity equation in two-dimensional topological field theory. We describe all integrable structures related to it: Hamiltonian, symplectic, and also recursion operators. We construct infinite hierarchies of symmetries and conservation laws.
Verbovetsky, A. M.; Vitolo, R.; Kersten, P.; Krasil'shchik, I. S.
The ADP-IV questionnaire: differential validity and concordance with the semi-structured interview.
The Assessment of DSM-IV Personality Disorders questionnaire (ADP-IV) is a self-report measure of the DSM-IV Axis II personality disorders (PDs). The ADP-IV assesses for each DSM-IV criterion its typicality as well as the accompanying distress and impairment. This study investigates two important aspects of the construct validity of the ADP-IV: (a) the differential validity (i.e., the ability to differentiate between a sample of the general Flemish population ( n = 659) and a sample of psychiatric inpatients ( n = 487) with a high prevalence of clinical PD diagnoses, and patients with and without a PD in the psychiatric sample; (b) the convergent validity with the SCID-II semi-structured interview in a population of psychiatric inpatients ( n = 59). The results indicate a good differential validity: the dimensional scales and the categorical measures discriminated well between both groups and between patients with and without a PD diagnosis in the psychiatric sample. Concerning the concordance with the SCID-II, a decent level of agreement is exemplified by a correlation of.67 between the dimensional total scores of both instruments and by kappa coefficients for an "any" Axis II diagnosis at the.50 level. In conclusion, the results indicate that the ADP-IV is an efficient method for assessing PD in dimensional and categorical ways. PMID:15342327
Schotte, Chris K W; De Doncker, Dirk A M; Dmitruk, Dorota; Van Mulders, Ineke; D'Haenen, Hugo; Cosyns, Paul
EPA Science Inventory
This paper gives an introductory account of Structural Equation Modeling (SEM) and demonstrates its application using LISREL< with a model utilizing environmental data. Using nine EMAP data variables, we analyzed their correlation matrix with an SEM model. The model characterized...
The relativistic equations of stellar structure and evolution
The general-relativistic equations of stellar structure and evolution are reformulated in a notation which makes easy contact with Newtonian theory. Also, a general-relativistic version of the mixing-length formalism for convection is presented.
Thorne, K. S.
The Strengths and Difficulties Questionnaire (SDQ): The Factor Structure and Scale Validation in U.S. Adolescents
The Strengths and Difficulties Questionnaire (SDQ) is one of the most commonly used instruments for screening psychopathology in children and adolescents. This study evaluated the hypothesized five-factor structure of the SDQ and examined its convergent validity against comprehensive clinical diagnostic assessments. Data were derived from the…
He, Jian-Ping; Burstein, Marcy; Schmitz, Anja; Merikangas, Kathleen R.
The 12Item General Health Questionnaire (GHQ12): Reliability, external validity and factor structure in the Spanish population
The purpose of this study was to analyze the internal consistency and the external and structure vali- dity of the 12-Item General Health Questionnaire (GHQ-12) in the Spanish general population. A stra- tified sample of 1001 subjects, ages between 25 and 65 years, taken from the general Spanish popula- tion was employed. The GHQ-12 and the Inventory of Situations and
María del Pilar Sánchez-López; Virginia Dresch
A Validation Study of the Dutch Childhood Trauma Questionnaire-Short Form: Factor Structure, Reliability, and Known-Groups Validity
Objective: The 28-item Childhood Trauma Questionnaire-Short Form (CTQ-SF) has been translated into at least 10 different languages. The validity of translated versions of the CTQ-SF, however, has generally not been examined. The objective of this study was to investigate the factor structure, internal consistency reliability, and known-groups…
Thombs, Brett D.; Bernstein, David P.; Lobbestael, Jill; Arntz, Arnoud
Brief report: The ego identity process questionnaire: Factor structure, reliability, and convergent validity in Dutch-speaking late adolescents
The reliability and validity of a Dutch version of the Ego Identity Process Questionnaire (EIPQ) were evaluated. In Study 1, the instrument was found to exhibit a clear factor structure and acceptable reliability. Using Confirmatory Factor Analysis, both a model with two process factors (Commitment, Exploration) and a model with four content factors (Ideological Commitment, Ideological Exploration, Interpersonal Commitment, Interpersonal
Koen Luyckx; Luc Goossens; Wim Beyers; Bart Soenens
Factor Structure and Reliability of the Childhood Trauma Questionnaire and Prevalence Estimates of Trauma for Male and Female Street Youth
This study examines the psychometric properties of the Childhood Trauma Questionnaire short form (CTQ-SF) with street youth who have run away or been expelled from their homes (N = 397). Internal reliability coefficients for the five clinical scales ranged from .65 to .95. Confirmatory Factor Analysis (CFA) was used to test the five-factor structure of the scales yielding acceptable fit
David R. Forde; Stephen W. Baron; Christine D. Scher; Murray B. Stein
Linear structural equations with latent variables
An interdependent multivariate linear relations model based on manifest, measured variables as well as unmeasured and unmeasurable latent variables is developed. The latent variables include primary or residual common factors of any order as well as unique factors. The model has a simpler parametric structure than previous models, but it is designed to accommodate a wider range of applications via
P. M. Bentler
Case Residuals in Structural Equation Modeling
From the beginning, lead methodologists in psychometrics and quantitative psychology have been well aware of the problems of fitting structural and confirmatory factor models. The question we approach in our research is how to best detect this misfit and how to identify specific sources of misfit by scrutinizing the data at the case level. Since…
Cardinale, John
Measuring physical activity among pregnant women using a structured one-week recall questionnaire: evidence for validity and reliability
Background Accurate measurement of the components of physical activity during pregnancy can aid in our understanding of the dose response relationships between physical activity and corresponding perinatal outcomes. The aim of this study was to develop and evaluate a one-week recall questionnaire to assess moderate to vigorous physical activity during pregnancy. Methods To assess concurrent-related validity, 177 pregnant women (median 18 weeks' gestation, interquartile range (IQR) 15 -23) kept a structured diary and wore an accelerometer (Actigraph) for one week. At the conclusion of the week, they completed the Pregnancy Infection and Nutrition 3 (PIN3) physical activity questionnaire over the telephone. To assess evidence for test-retest reliability, 109 pregnant women (median 19 weeks' gestation, IQR 18-27) completed the questionnaire twice over the telephone, within 48 hours apart, recalling the same two time periods. Spearman correlation coefficients (SCC) and intraclass correlation coefficients (ICC) were used to assess evidence for validity and reliability, respectively. Results Comparison of the questionnaire to the structured diary was moderate to substantial (SCC 0.47 to 0.69) for several measures of moderate or vigorous physical activity using either perceived or absolute intensity. Comparison of moderate to vigorous physical activity from the questionnaire (absolute intensity using MET-hours/week) to the accelerometer ranged from 0.12 to 0.23 using SCC for absolute intensity (MET-hours/week) and 0.28 to 0.34 using relative intensity (hours/week) (n = 177). Test-retest reliability was moderate to almost perfect for moderate to vigorous physical activity, with the ICC ranging from 0.56 to 0.82 for both perceived and absolute intensities. Conclusions The PIN3 one-week recall questionnaire assessed moderate to vigorous physical activity in the past week with evidence for reliability and validity.
Simple nonlinear equation for structural relaxation in glasses.
A wide range of glassy and disordered materials exhibit complex, nonexponential, structural relaxation (aging). We propose a simple nonlinear rate equation ? = a[1-exp(b ?)], where ? is the normalized deviation of a macroscopic variable from its equilibrium value, to describe glassy relaxation. Analysis of extensive experimental data shows that this equation quantitatively captures structural relaxation, where a and b are both temperature- and, more importantly, history-dependent parameters. This analysis explicitly demonstrates that structural relaxation cannot be accurately described by a single nonequilibrium variable. Relaxation rates extracted from the data imply the existence of cooperative rearrangements on a supermolecular scale. PMID:23005357
Kolvin, Itamar; Bouchbinder, Eran
Structural Equation Modelling: A Primer for Music Education Researchers
Structural equation modelling (SEM) is a method for analysis of multivariate data from both non-experimental and experimental research. The method combines a structural model linking latent variables and a measurement model linking observed variables with latent variables. Its use in social science and educational research has grown since the…
Teo, Timothy
Exploring ecological patterns with structural equation modeling and Bayesian analysis
Structural equation modeling is a multivariate statistical method that allows evaluation of a network of relationships between manifest and latent variables. In this statistical technique, preconceptualizations that reflect research questions or existing knowledge of system structure create the initial framework for model development, while both direct and indirect effects and measurement errors are considered. Given the interesting features of this
G. B. Arhonditsis; C. A. Stow; L. J. Steinberg; M. A. Kenney; R. C. Lathrop; S. J. McBride; K. H. Reckhow
Structural Equation Modeling of School Violence Data: Methodological Considerations
Methodological challenges associated with structural equation modeling (SEM) and structured means modeling (SMM) in research on school violence and related topics in the social and behavioral sciences are examined. Problems associated with multiyear implementations of large-scale surveys are discussed. Complex sample designs, part of any…
Mayer, Matthew J.
On integrable structures for a generalized Monge-Ampere equation
We consider a 3rd-order generalized Monge-Ampere equation u_yyy - u_xxy^2 + u_xxx u_xyy = 0 (which is closely related to the associativity equation in the 2-d topological field theory) and describe all integrable structures related to it (i.e., Hamiltonian, symplectic, and recursion operators). Infinite hierarchies of symmetries and conservation laws are constructed as well.
Paul Kersten; Iosif Krasil'shchik; Alexander Verbovetsky; Raffaele Vitolo
The Structure of Perceived Emotional Control: Psychometric Properties of a Revised Anxiety Control Questionnaire
The psychometric properties of the Anxiety Control Questionnaire (ACQ) were evaluated in 1,550 outpatients with DSM-IV anxiety and mood disorders and 360 nonclinical participants. Counter to prior findings, exploratory factor analyses produced a 3-factor solution (Emotion Control, Threat Control, Stress Control) based on 15 of the ACQ's original…
Brown, Timothy A.; White, Kamila S.; Forsyth, John P.; Barlow, David H.
The Social Coping Questionnaire: An Examination of Its Structure with an American Sample of Gifted Adolescents
Gifted students report that they are often perceived differently than nonidentified students (Cross, Coleman, & Stewart, 1993); thus, they employ social coping strategies to manipulate the visibility of their giftedness. The Social Coping Questionnaire (SCQ; Swiatek, 1995) was designed to assess these strategies. This study's purpose was to…
Rudasill, Kathleen Moritz; Foust, Regan Clark; Callahan, Carolyn M.
Psychometric Evidence for the Leisure Interest Questionnaire and Analyses of the Structure of Leisure Interests
This study provides evidence of reliability and validity for the Leisure Interest Questionnaire (LIQ; J. C. Hansen, 1998). Undergraduate students completed the LIQ and Strong Interest Inventory (SII; E. K. Strong Jr., 1927) at Time 1 and the LIQ 5 weeks later. The internal consistency and test-retest reliability of the LIQ scales were calculated.…
Hansen, Jo-Ida C.; Scullard, Mark G.
The development of the multidimensional locus of pain control questionnaire (MLPC): Factor structure, reliability, and validity
This study was conducted to develop a comprehensive Multidimensional Locus of Pain Control questionnaire (MLPC) and to examine how locus of pain control is related to pain appraisals, pain coping strategies, and adjustment to chronic pain. Subjects were 170 chronic headache patients. By means of factor analysis, four subscales were derived: an Internal, a Chance, a Physician, and a Medication
Moniek M. Kuile; A. Corry G. Linssen; Philip Spinhoven
Factor Structure of the Penn State Worry Questionnaire: Examination of a Method Factor
The Penn State Worry Questionnaire (PSWQ) was originally designed as a unifactorial measure of pathological trait worry. However, recent studies supported a two-factor solution with positively worded items loading on the first factor and reverse-scored items loading on a second factor. The current study compared this two-factor model to a negative…
Hazlett-Stevens, Holly; Ullman, Jodie B.; Craske, Michelle G.
The Home Situations Questionnaire-PDD Version: Factor Structure and Psychometric Properties
Background: The Home Situations Questionnaire (HSQ) is a caregiver-rated scale designed to assess behavioural non-compliance in everyday settings that has been used in several studies in typically developing children. Currently there is no accepted measure of behavioural non-compliance in children with pervasive developmental disorders (PDDs).…
Chowdhury, M.; Aman, M. G.; Scahill, L.; Swiezy, N.; Arnold, L. E.; Lecavalier, L.; Johnson, C.; Handen, B.; Stigler, K.; Bearss, K.; Sukhodolsky, D.; McDougle, C. J.
Component Structure, Reliability, and Stability of Lawrence's Self-Esteem Questionnaire (LAWSEQ)
Lawrence's Self-Esteem Questionnaire (LAWSEQ) was administered to 120 Year 1 pupils in six schools in Belfast, Northern Ireland. A principal components analysis indicated that the scale items were unidimensional and that the reliability of the scores, as estimated by Cronbach's alpha, was satisfactory ([alpha] = 0.73). There were no differences…
Rae, Gordon; Dalto, Georgia; Loughrey, Dolores; Woods, Caroline
Reporting Results from Structural Equation Modeling Analyses in Archives of Scientific Psychology
Psychological research typically involves the analysis of data (e.g., questionnaire responses, records of behavior) using statistical methods. The description of how those methods are used and the results they produce is a key component of scholarly publications. Despite their importance, these descriptions are not always complete and clear. In order to ensure the completeness and clarity of these descriptions, the Archives of Scientific Psychology requires that authors of manuscripts to be considered for publication adhere to a set of publication standards. Although the current standards cover most of the statistical methods commonly used in psychological research, they do not cover them all. In this manuscript, we propose adjustments to the current standards and the addition of additional standards for a statistical method not adequately covered in the current standards—structural equation modeling (SEM). Adherence to the standards we propose would ensure that scholarly publications that report results of data analyzed using SEM are complete and clear. Scientific Abstract We recommend reporting standards consistent with the Journal Article Reporting Standards (JARS) of the American Psychological Association for manuscripts in which results from structural equation modeling (SEM) analyses are presented. For all sections of the general JARS except the results section, we recommend minor adjustments. For the results section of the JARS, we provide a supplemental module specific to reports of research that use SEM. The result is a questionnaire that ensures thorough and detailed reports of SEM analyses in the Archives.
Hoyle, Rick H.; Isherwood, Jennifer C.
The short version of the Defense Style Questionnaire: factor structure and psychopathological correlates
The Defense Style Questionnaire (DSQ) is a self-report inventory that measures specific defense mechanisms in terms of DSM-III-R concepts. In the present study, normal subjects completed the short version of the DSQ. DSQ scores were then subjected to a factor analysis. This analysis revealed a three-factor solution with immature defenses loading on the first, mature defenses loading on the second,
Peter Muris; Harald Merckelbach
Examining the cognitive model of caregiving - A structural equation modelling approach.
The study tests assumptions from the "cognitive model of caregiving" (Kuipers et al., 2010), which aims to inform interventions for carers of people with psychoses. The sample comprised 61 relatives of patients with schizophrenia. Standardized psychological assessments were conducted twice within 6 months including Involvement Evaluation Questionnaire (IEQ-EU), a short form of the Symptom Checklist 90-R (SCL K9), the Family Questionnaire (FQ), scales measuring control attributions of the Illness Perception Questionnaire for Schizophrenia (IPQS-R) and emotions toward the ill relative. Structural equation modelling was used to analyse data. We identified two pathways: (a) from "attributing control to relatives" to distress, intermediated by anxiety for the patient and emotional overinvolvement (EOI), and (b) from "attribution control to patient" to distress, intermediated by anger about the patient and criticism. The model provided a good fit to the data and was successfully replicated at a second point in time. We were able to find supporting evidence for a cognitive model of caregiving. Control attributions and emotions of informal caregivers are important when interventions are planned reducing expressed emotion and burden of caregivers. PMID:24740133
Hesse, Klaus; Klingberg, Stefan
Bayesian Estimation and Testing of Structural Equation Models.
Explains how the Gibbs sampler can be applied to obtain a sample from the posterior distribution over the parameters of a structural equation model. Presents statistics to use to summarize marginal posterior densities and model checks using posterior predictive p-values. (SLD)
Scheines, Richard; Hoijtink, Herbert; Boomsma, Anne
Modeling Dynamic Functional Neuroimaging Data Using Structural Equation Modeling
The aims of this study were to present a method for developing a path analytic network model using data acquired from positron emission tomography. Regions of interest within the human brain were identified through quantitative activation likelihood estimation meta-analysis. Using this information, a "true" or population path model was then developed using Bayesian structural equation modeling. To evaluate the impact
Larry R. Price; Angela R. Laird; Peter T. Fox; Roger J. Ingham
Bayesian structural equation modeling method for hierarchical model validation
A building block approach to model validation may proceed through various levels, such as material to component to subsystem to system, comparing model predictions with experimental observations at each level. Usually, experimental data becomes scarce as one proceeds from lower to higher levels. This paper presents a structural equation modeling approach to make use of the lower-level data for higher-level
Xiaomo Jiang; Sankaran Mahadevan
Bayesian estimation and testing of structural equation models
The Gibbs sampler can be used to obtain samples of arbitrary size from the posterior distribution over the parameters of a structural equation model (SEM) given covariance data and a prior distribution over the parameters. Point estimates, standard deviations and interval estimates for the parameters can be computed from these samples. If the prior distribution over the parameters is uninformative,
Richard Scheines; Herbert Hoijtink; Anne Boomsma
The temporal structure of intensity scintillations near the magnetic equator
The temporal structure of weak and strong intensity scintillations observed with a geostationary satellite at 249 MHz near the magnetic equator is investigated. Results show that the power spectra for weak intensity scintillations exhibit an asymptote immediately beyond the Fresnel frequency, which denotes a power law variation of power spectral density with frequency yielding spectral indices ranging between -3 and
Santimay Basu; H. E. Whitney
Evaluating Interventions with Multimethod Data: A Structural Equation Modeling Approach
In many intervention and evaluation studies, outcome variables are assessed using a multimethod approach comparing multiple groups over time. In this article, we show how evaluation data obtained from a complex multitrait-multimethod-multioccasion-multigroup design can be analyzed with structural equation models. In particular, we show how the…
Crayen, Claudia; Geiser, Christian; Scheithauer, Herbert; Eid, Michael
Estimating Multilevel Linear Models as Structural Equation Models
Multilevel linear models (MLMs) provide a powerful framework for analyzing data collected at nested or non-nested levels, such as students within classrooms. The current article draws on recent analytical and software advances to demonstrate that a broad class of MLMs may be estimated as structural equation models (SEMs). Moreover, within the SEM…
Bauer, Daniel J.
The General Linear Model as Structural Equation Modeling
Statistical procedures based on the general linear model (GLM) share much in common with one another, both conceptually and practically. The use of structural equation modeling path diagrams as tools for teaching the GLM as a body of connected statistical procedures is presented. A heuristic data set is used to demonstrate a variety of univariate…
Graham, James M.
A Bayesian Approach for Analyzing Longitudinal Structural Equation Models
This article considers a Bayesian approach for analyzing a longitudinal 2-level nonlinear structural equation model with covariates, and mixed continuous and ordered categorical variables. The first-level model is formulated for measures taken at each time point nested within individuals for investigating their characteristics that are dynamically…
Song, Xin-Yuan; Lu, Zhao-Hua; Hser, Yih-Ing; Lee, Sik-Yum
Local Influence Analysis of Nonlinear Structural Equation Models
By regarding the latent random vectors as hypothetical missing data and based on the conditional expectation of the complete-data log-likelihood function in the EM algorithm, we investigate assessment of local influence of various perturbation schemes in a nonlinear structural equation model. The basic building blocks of local influence analysis…
Lee, Sik-Yum; Tang, Nian-Sheng
Bayesian Data-Model Fit Assessment for Structural Equation Modeling
Bayesian approaches to modeling are receiving an increasing amount of attention in the areas of model construction and estimation in factor analysis, structural equation modeling (SEM), and related latent variable models. However, model diagnostics and model criticism remain relatively understudied aspects of Bayesian SEM. This article describes…
Levy, Roy
Principles and practice in reporting structural equation analyses
Principles for reporting analyses using structural equation modeling are reviewed, with the goal of supplying readers with complete and accurate information. It is recommended that every report give a detailed justification of the model used, along with plausible alternatives and an account of identifiability. Nonnormality and missing data problems should also be addressed. A complete set of parameters and their
Roderick P. McDonald; Moon-Ho Ringo Ho
Multiple Imputation Strategies for Multiple Group Structural Equation Models
Although structural equation modeling software packages use maximum likelihood estimation by default, there are situations where one might prefer to use multiple imputation to handle missing data rather than maximum likelihood estimation (e.g., when incorporating auxiliary variables). The selection of variables is one of the nuances associated with implementing multiple imputation, because the imputer must take special care to preserve
Craig K. Enders; Amanda C. Gottschall
Effects of Employing Ridge Regression in Structural Equation Models.
LISREL 8 invokes a ridge option when maximum likelihood or generalized least squares are used to estimate a structural equation model with a nonpositive definite covariance or correlation matrix. Implications of the ridge option for model fit, parameter estimates, and standard errors are explored through two examples. (SLD)
McQuitty, Shaun
Asymptotic Biases in Exploratory Factor Analysis and Structural Equation Modeling
Formulas for the asymptotic biases of the parameter estimates in structural equation models are provided in the case of the Wishart maximum likelihood estimation for normally and nonnormally distributed variables. When multivariate normality is satisfied, considerable simplification is obtained for the models of unstandardized variables. Formulas…
Ogasawara, Haruhiko
Sensitivity Analysis in Structural Equation Models: Cases and Their Influence
The detection of outliers and influential observations is routine practice in linear regression. Despite ongoing extensions and development of case diagnostics in structural equation models (SEM), their application has received limited attention and understanding in practice. The use of case diagnostics informs analysts of the uncertainty of model…
Pek, Jolynn; MacCallum, Robert C.
A Note on Structural Equation Modeling Estimates of Reliability
Reliability can be estimated using structural equation modeling (SEM). Two potential problems with this approach are that estimates may be unstable with small sample sizes and biased with misspecified models. A Monte Carlo study was conducted to investigate the quality of SEM estimates of reliability by themselves and relative to coefficient…
Yang, Yanyun; Green, Samuel B.
Structural Equation Modeling And Regression: Guidelines For Research Practice
The growing interest in Structured Equation Modeling (SEM) techniquesand recognition of their importance in IS research suggests the need to compareand contrast different types of SEM techniques so that research designs can beappropriately selected. After assessing the extent to which these techniques arecurrently being used in IS research, the article presents a running example whichanalyzes the same dataset via three
David Gefen; Detmar W. Straub; Marie-claude Boudreau
Analyzing Mixed-Dyadic Data Using Structural Equation Models
Mixed-dyadic data, collected from distinguishable (nonexchangeable) or indistinguishable (exchangeable) dyads, require statistical analysis techniques that model the variation within dyads and between dyads appropriately. The purpose of this article is to provide a tutorial for performing structural equation modeling analyses of cross-sectional…
Peugh, James L.; DiLillo, David; Panuzio, Jillian
Mental Capacity and Role Taking: A Structural Equations Approach.
Used a data analytic strategy that was novel to the M-space literature to examine the mental capacity prerequisites of social-cognitive development of 99 students in grades one, three, and five. Used a structural equations analysis to determine whether M-power was a significant predictor of role-taking development. (RH)
Lapsley, Daniel K.; Quintana, Stephen M.
Using Fixed Thresholds with Grouped Data in Structural Equation Modeling
Valuable methods have been developed for incorporating ordinal variables into structural equation models using a latent response variable formulation. However, some model parameters, such as the means and variances of latent factors, can be quite difficult to interpret because the latent response variables have an arbitrary metric. This limitation…
Koran, Jennifer; Hancock, Gregory R.
Maximum Likelihood Estimation of Nonlinear Structural Equation Models.
Developed an EM type algorithm for maximum likelihood estimation of a general nonlinear structural equation model in which the E-step is completed by a Metropolis-Hastings algorithm. Illustrated the methodology with results from a simulation study and two real examples using data from previous studies. (SLD)
Lee, Sik-Yum; Zhu, Hong-Tu
Play Context, Commitment, and Dating Violence: A Structural Equation Model
This study develops a structural equation model to describe the effect of two groups of factors (type of commitment and play context) on the violence experienced during intimate partner conflict. After contrasting the model in adolescents and university students, we have confirmed that aggressive play and the simulation of jealousy and anger…
Gonzalez-Mendez, Rosaura; Hernandez-Cabrera, Juan Andres
Signal processing in the cochlea: The structure equations
Background Physical and physiological invariance laws, in particular time invariance and local symmetry, are at the outset of an abstract model. Harmonic analysis and Lie theory are the mathematical prerequisites for its deduction. Results The main result is a linear system of partial differential equations (referred to as the structure equations) that describe the result of signal processing in the cochlea. It is formulated for phase and for the logarithm of the amplitude. The changes of these quantities are the essential physiological observables in the description of signal processing in the auditory pathway. Conclusions The structure equations display in a quantitative way the subtle balance for processing information on the basis of phase versus amplitude. From a mathematical point of view, the linear system of equations is classified as an inhomogeneous - equation. In suitable variables the solutions can be represented as the superposition of a particular solution (determined by the system) and a holomorphic function (determined by the incoming signal). In this way, a global picture of signal processing in the cochlea emerges.
The Greek version of the Revised Person's Relating to Others Questionnaire (PROQ2-GR): psychometric properties and factor structure.
The Revised Person's Relating to Others Questionnaire (PROQ2) is a self-administered questionnaire of 96 items for measuring a person's negative relating. Its eight scales correspond to the eight octants of the theoretical structure called the interpersonal octagon, which is based upon the assumption that relating occurs along a horizontal, close-distant axis and a vertical, upper-lower axis. The present study concerns the Greek translation of the questionnaire called the PROQ2-GR. The psychometric properties and the factor structure of the PROQ2-GR were studied in a Greek population sample of 457. The findings were compared with those of an English population sample of 276. All scales showed good internal reliability. Four factors were extracted, representing the four main poles of the interpersonal octagon, with good psychometric properties. The positive correlations between all adjacent scales and the negative correlations between certain pairs of opposite scales are as would be expected in a model of circular ordering. The PROQ2-GR showed a greater degree of bipolarity than the PROQ2. Women were significantly more upper close and neutral close than men. The Greeks had a higher total mean score than the English and had higher mean scores on five out of the eight scales. PMID:14577895
Kalaitzaki, Argyroula E; Nestoros, Joannis N
Post-partum blues among Korean mothers: a structural equation modelling approach.
The objective of this study was to propose the post-partum blues (PPB) model and to estimate the effects of self-esteem, social support, antenatal depression, and stressful events during pregnancy on PPB. Data were collected from 249 women post-partum during their stay in the maternity units of three hospitals in Korea using a self-administered questionnaire. A structural equation modelling approach using the Analysis of Moments Structure program was used to identify the direct and indirect effects of the variables on PPB. The full model had a good fit and accounted for 70.3% of the variance of PPB. Antenatal depression and stressful events during pregnancy had strong direct effects on PPB. Household income showed indirect effects on PPB via self-esteem and antenatal depression. Social support indirectly affected PPB via self-esteem, antenatal depression, and stressful events during pregnancy. PMID:23009567
Chung, Sung Suk; Yoo, Il Young; Joung, Kyoung Hwa
Local structure-preserving algorithms for the "good" Boussinesq equation
In this paper, we derive a series of local structure-preserving algorithms for the "good" Boussinesq equation, including multisymplectic geometric structure-preserving algorithms, local energy-preserving algorithms and local momentum-preserving algorithms. The outstanding advantage of the proposed algorithms is that they conserve these local structures in any time-space region exactly. For example, the proposed local energy-preserving algorithms preserve the local energy conservation law in any local domain. Therefore, the local structure-preserving algorithms overcome the shortage of global structure-preserving algorithms on the boundary conditions. Especially, with suitable boundary conditions such as periodic or homogeneous boundary conditions, the local structure-preserving algorithms will be global structure-preserving algorithms. Numerical results verify the theoretical analysis.
Cai, Jiaxiang; Wang, Yushun
General structure of the Thomas-Fermi equation of state
We derive the behavior of the Thomas-Fermi equation of state near both the hot-curve'' (the limit as {ital T}{r arrow}{infinity} for a fixed de Broglie length) and the cold-curve'' (the zero-temperature isotherm) by using perturbation methods. We derive efficient computational formulas for the coefficients in these expansions using Pade methods. We are able to meld all of these results into a structurally correct representation of the Thomas-Fermi fluid pressure. We indicate how this representational structure can be used to construct the equation of state for realistic materials over large ranges of temperature and pressure. We also discuss the computation of the degree of ionization with and without the exchange correction.
Baker, G.A. Jr.; Johnson, J.D. (Theoretical Division, Los Alamos National Laboratory, University of California, Los Alamos, New Mexico (USA))
Multidisciplinary optimization of controlled space structures with global sensitivity equations
A new method for the preliminary design of controlled space structures is presented. The method coordinates standard finite element structural analysis, multivariable controls, and nonlinear programming codes and allows simultaneous optimization of the structures and control systems of a spacecraft. Global sensitivity equations are a key feature of this method. The preliminary design of a generic geostationary platform is used to demonstrate the multidisciplinary optimization method. Fifteen design variables are used to optimize truss member sizes and feedback gain values. The goal is to reduce the total mass of the structure and the vibration control system while satisfying constraints on vibration decay rate. Incorporating the nonnegligible mass of actuators causes an essential coupling between structural design variables and control design variables. The solution of the demonstration problem is an important step toward a comprehensive preliminary design capability for structures and control systems. Use of global sensitivity equations helps solve optimization problems that have a large number of design variables and a high degree of coupling between disciplines.
Padula, Sharon L.; James, Benjamin B.; Graves, Philip C.; Woodard, Stanley E.
Structure of Neutron Stars with Unified Equations of State
We present a set of three unified equations of states (EoSs) based on the nuclear energy-density functional (EDF) theory. These EoSs are based on generalized Skyrme forces fitted to essentially all experimental atomic mass data and constrained to reproduce various properties of infinite nuclear matter as obtained from many-body calculations using realistic two- and three-body interactions. The structure of cold isolated neutron stars is discussed in connection with some astrophysical observations.
Fantina, A. F.; Chamel, N.; Pearson, J. M.; Goriety, S.
The Importance of Structure Coefficients in Structural Equation Modeling Confirmatory Factor Analysis.
A general linear model (GLM) framework is used to suggest that structure coefficients ought to be interpreted in structural equation modeling confirmatory factor analysis (CFA) studies in which factors are correlated. The computation of structure coefficients in explanatory factor analysis and CFA is explained. Two heuristic data sets are used to…
Thompson, Bruce
Factor structure of the Sociocultural Attitudes Towards Appearance Questionnaire-3 (SATAQ-3) among adolescent boys in China.
There is considerable evidence that mass media portrayals of body image contribute to body dissatisfaction, yet the assessment of perceived media influences has been examined fleetingly in highly populated, non-Western cultures, particularly among young males. This research examined the factor structure of the Sociocultural Attitudes Towards Appearance Questionnaire-3 (SATAQ-3) among adolescent boys in China. In an initial exploratory factor analysis (N=719), a four factor solution emerged with components reflecting General Pressure-Internalization, Sources of Appearance Information, Pressure-Internalization of an Athletic Ideal, and Pressure to be Thin. Subsequently, confirmatory factor analyses in a new sample (n=749) assessed fits of the derived four factor model, a three factor variant, and alternatives reflecting "Western" and "Malay" SATAQ-3 solutions. The derived four factor solution had the most acceptable structure across several fit indices. Patterns of correlation with other self-report measures also provided preliminary support for the validity of the derived solution. PMID:20800561
Jackson, Todd; Chen, Hong
Initial validation of the Spanish childhood trauma questionnaire-short form: factor structure, reliability and association with parenting.
The present study examines the internal consistency and factor structure of the Spanish version of the Childhood Trauma Questionnaire-Short Form (CTQ-SF) and the association between the CTQ-SF subscales and parenting style. Cronbach's ? and confirmatory factor analyses (CFA) were performed in a female clinical sample (n = 185). Kendall's ? correlations were calculated between the maltreatment and parenting scales in a subsample of 109 patients. The Spanish CTQ-SF showed adequate psychometric properties and a good fit of the 5-factor structure. The neglect and abuse scales were negatively associated with parental care and positively associated with overprotection scales. The results of this study provide initial support for the reliability and validity of the Spanish CTQ-SF. PMID:23266990
Hernandez, Ana; Gallardo-Pujol, David; Pereda, Noemí; Arntz, Arnoud; Bernstein, David P; Gaviria, Ana M; Labad, Antonio; Valero, Joaquín; Gutiérrez-Zotes, Jose Alfonso
Selected Neurophysiological, Psychological, and Behavioral Influences on Subjective Sleep Quality in Nurses: A Structure Equation Model
Few studies have examined relationships among neurophysiological, psychological, and behavioral factors with regard to their effects on sleep quality. We used a structure equation model to investigate behavioral and psychological factors that influence neurophysiological regulation of sleep in shift workers. Using a cross-sectional study design, we tested the model with a sample of 338 female nurses working rotating shifts at an urban regional hospital. The Morningness-Eveningness Questionnaire (MEQ) and short-form Menstrual Distress Questionnaire (MDQ) were used to measure neurophysiological factors involved in morningness-eveningness and menstrual distress. The Sleep Hygiene Awareness and Practice Scale (SHAPS) and Profile of Mood States Short Form (POMS-SF) were completed to measure behavioral factors of sleep hygiene practices and psychological factors of mood states. In addition, the Pittsburgh Sleep Quality Index (PSQI) measured participant's self-reported sleep quality. The results revealed that sleep hygiene practices and mood states mediated the effects of morningness-eveningness and menstrual distress on sleep quality. Our findings provide support for developing interventions to enhance sleep hygiene and maintain positive mood states to reduce the influence of neurophysiological factors on sleep quality among shift workers.
Chung, Min-Huey; Liu, Wen-I; Lee, Hui-Ling; Hsu, Nanly
General Integrals and the Structure of General Solution of the Chew-Low Equations.
The obtained before functional equations for the structural functions which determine the structure of two general integrals of Chew-Low equations are solved. The general integrals are found in approximation which makes it possible by inverting them to ob...
K. V. Rerikh
Fluid-structural interactions using Navier-Stokes flow equations coupled with shell finite element structures
A computational procedure is presented to study fluid-structural interaction problems for three-dimensional aerospace structures. The flow is modeled using the three-dimensional unsteady Euler/Navier-Stokes equations and solved using the finite-difference approach. The three dimensional structure is modeled using shell/plate finite-element formulation. The two disciplines are coupled using a domain decomposition approach. Accurate procedures both in time and space are developed to combine the solutions from the flow equations with those of the structural equations. Time accuracy is maintained using aeroelastic configuration-adaptive moving grids that are computed every time step. The work done by aerodynamic forces due to structural deformations is preserved using consistent loads. The present procedure is validated by computing the aeroelastic response of a wing and comparing with experiment. Results are illustrated for a typical wing-body configuration.
Guruswamy, Guru P.; Byun, Chansup
The Family Strain Index (FSI). Reliability, validity, and factor structure of a brief questionnaire for families of children with ADHD
\\u000a Abstract\\u000a \\u000a \\u000a Background\\u000a Attention-deficit\\/hyperactivity disorder (ADHD) in children affects every member of the family. Practical tools are needed\\u000a to assess the effects of ADHD on families to better understand and address the level of stress, strain and burden that families\\u000a experience.\\u000a \\u000a \\u000a \\u000a \\u000a Objective\\u000a To provide the preliminary reliability, validity and factor structure of the Family Strain Index (FSI), a 6-item parent-report\\u000a questionnaire.
Anne W. Riley; Lisa M. Lyman; Georg Spiel; Manfred Döpfner; Maria J. Lorenzo
[Resources and Self-Management Skills in Multiple Sclerosis Patients - Can the Scale Structure of the Questionnaire FERUS be Replicated?].
To assess resources and self-management skills the generic questionnaire FERUS was developed by Jack (2007) and validated and standardized in a sample of psychosomatic patients and of healthy people. The aim of this study was the psychometric review of the FERUS with a sample of patients with Multiple Sclerosis (MS).The dimensional structure identified by Jack was replicated in an exploratory factor analyses as well as tested in a confirmatory factor analyses and the discrimination ability of the scales was examined.Jack's results of the exploratory factor analyses and scale analyses were replicated essentially. After elimination of non-theory-compliant items, differentiation of the construct "motivation for change" and insertion of a second-order construct "self-management skills" a good confirmatorical model fit could be achieved.The FERUS can be used for MS patients. The consideration of optimization proposals allows higher construct validity and a more economical use of FERUS. PMID:24217882
Feicke, J; Spörhase, U; Wirtz, M
Invited commentary: structural equation models and epidemiologic analysis.
In this commentary, structural equation models (SEMs) are discussed as a tool for epidemiologic analysis. Such models are related to and compared with other analytic approaches often used in epidemiology, including regression analysis, causal diagrams, causal mediation analysis, and marginal structural models. Several of these other approaches in fact developed out of the SEM literature. However, SEMs themselves tend to make much stronger assumptions than these other techniques. SEMs estimate more types of effects than do these other techniques, but this comes at the price of additional assumptions. Many of these assumptions have often been ignored and not carefully evaluated when SEMs have been used in practice. In light of the strong assumptions employed by SEMs, the author argues that they should be used principally for the purposes of exploratory analysis and hypothesis generation when a broad range of effects are potentially of interest. PMID:22956513
VanderWeele, Tyler J
Equation of state and structural changes in diaminodinitroethylene under compression.
Structural changes in 1,1-diamino-2,2-dinitroethylene (DADNE, FOX-7) compressed to high pressure in diamond anvil cells were investigated using angle-dispersive x-ray diffraction analysis, Raman spectroscopy, and optical polarizing microscopy. The x-ray results show several changes above 1 GPa. When the x-ray data are indexed according to the ambient-pressure structure, DADNE shows anisotropic compression, with higher compression along the b axis than along the a or c axis. An ambient-temperature isothermal equation of state of DADNE was generated from these data. In addition, the experimentally obtained Raman spectra were matched with vibrational normal modes calculated using quantum chemistry calculations. The shifts in vibrational modes indicate changes in H-wagging vibrations with pressure. PMID:15267725
Peiris, Suhithi M; Wong, Chak P; Zerilli, Frank J
Reporting Multiple-Group Mean and Covariance Structure across Occasions with Structural Equation Modeling
Objectives: Using baseline and second wave data, the study evaluated the measurement and structural properties of parenting stress, personal mastery, and economic strain with N = 381 lower income parents who decided to join and those who did not join in a child development savings account program. Methods: Structural equation modeling mean and…
Okech, David
[Self-evaluation questionnaires--factorial structure and indications for general practice].
The following self-rating inventories were administered to 613 subjects (289 psychically ill patients and 324 healthy persons): The Basel Mood Inventory (BBI), the Freiburg Personality Inventory (FPI), the Giessen-Test (GT), the Complaint-List (HHM), and the Paranoid-Neuroticism-Depression-Scale (PND-S'). The main interest was put on examining the dimensionality of each inventory separately and all the inventories combined. The results are discussed with respect to the practical applicability. FPI and GT proved as two polyvalently applicable personality inventories (clinically as well as non-clinically) whose factorial structure is essentially verified. It was justified to eliminate "N" (neuroticism) from the PND in the newly revised version. Although "P" (paranoid) covers only a particular domain of paranoid tendencies the new test version (PD and PD') will be valuable in clinical use for group differentiation (a.o. for global diagnoses of depression and schizophrenia) in longitudinal as well as cross-sectional studies. The HHM covers mood state variables additionally, little differentiated though. The newer parallel forms suffer from the same deficiency. It could be confirmed that the BBI measures a particular mood-drive dimension and thus can be used independently or in combination with multidimensional personality inventories in longitudinal studies. PMID:6710085
Hobi, V
Factorial Invariance and Latent Mean Structure of Questionnaires Measuring Social-Cognitive Determinants of Physical Activity among Black and White Adolescent Girls
Background. We previously developed questionnaires based on contemporary theories to measure physical activity determinants among youth [Motl et al., Prev Med 2000; 31:584–94]. The present study examined the factorial invariance and latent mean structure of unidimensional models fit to the questionnaires measuring attitude, subjective norm, perceived behavioral control, and self-efficacy about physical activity among black and white adolescent girls.Methods. Black
R. K. Dishman; R. W. Motl; R. P. Saunders; M. Dowda; G. Felton; D. S. Ward; R. R. Pate
Factor structure, reliability, and known groups validity of the German version of the Childhood Trauma Questionnaire (Short-form) in Swiss patients and nonpatients.
The Childhood Trauma Questionnaire-Short Form is the most widely used instrument to assess childhood trauma and has been translated into 10 languages. However, research into validity and reliability of these translated versions is scarce. The present study aimed to investigate the factor structure, internal consistency, reliability, and known-groups validity of the German Childhood Trauma Questionnaire-Short Form (Bernstein & Fink, 1998). Six-hundred and sixty-one clinical and nonclinical participants completed the German Childhood Trauma Questionnaire-Short Form. A confirmatory factor analysis was conducted to assess the 5-factor structure of the original Childhood Trauma Questionnaire-Short Form. To investigate known-groups validity, the confirmatory factor analysis latent factor levels between clinical and nonclinical participants were compared. The original 5-factor structure was confirmed, with only the Physical Neglect scale showing rather poor fit. As a conclusion, the results support the validity and reliability of the German Childhood Trauma Questionnaire-Short Form. It is recommended to use the German Childhood Trauma Questionnaire-Short Form to assess experiences of childhood trauma. PMID:24641795
Karos, Kai; Niederstrasser, Nils; Abidi, Latifa; Bernstein, David P; Bader, Klaus
The algebraic structure behind the derivative nonlinear Schrödinger equation
The Kaup-Newell (KN) hierarchy contains the derivative nonlinear Schrödinger equation (DNLSE) amongst others interesting and important nonlinear integrable equations. In this paper, a general higher grading affine algebraic construction of integrable hierarchies is proposed and the KN hierarchy is established in terms of an \\hat{s\\ell }_2 Kac-Moody algebra and principal gradation. In this form, our spectral problem is linear in the spectral parameter. The positive and negative flows are derived, showing that some interesting physical models arise from the same algebraic structure. For instance, the DNLSE is obtained as the second positive, while the Mikhailov model as the first negative flows. The equivalence between the latter and the massive Thirring model is also explicitly demonstrated. The algebraic dressing method is employed to construct soliton solutions in a systematic manner for all members of the hierarchy. Finally, the equivalence of the spectral problem introduced in this paper with the usual one, which is quadratic in the spectral parameter, is achieved by setting a particular automorphism of the affine algebra, which maps the homogeneous into principal gradation.
França, G. S.; Gomes, J. F.; Zimerman, A. H.
Structural precursor to freezing: An integral equation study
Recent simulation studies have drawn attention to the shoulder which forms in the second peak of the radial distribution function of hard spheres at densities close to freezing and which is associated with local crystalline ordering in the dense fluid. We address this structural precursor to freezing using an inhomogeneous integral equation theory capable of describing local packing constraints to a high level of accuracy. The addition of a short-range attractive interaction leads to a well known broadening of the fluid-solid coexistence region as a function of attraction strength. The appearance of a shoulder in our calculated radial distribution functions is found to be consistent with the broadened coexistence region for a simple model potential, thus demonstrating that the shoulder is not exclusively a high density packing effect.
Brader, Joseph M.
Structural equation modeling in medical research: a primer
Background Structural equation modeling (SEM) is a set of statistical techniques used to measure and analyze the relationships of observed and latent variables. Similar but more powerful than regression analyses, it examines linear causal relationships among variables, while simultaneously accounting for measurement error. The purpose of the present paper is to explicate SEM to medical and health sciences researchers and exemplify their application. Findings To facilitate its use we provide a series of steps for applying SEM to research problems. We then present three examples of how SEM has been utilized in medical and health sciences research. Conclusion When many considerations are given to research planning, SEM can provide a new perspective on analyzing data and potential for advancing research in medical and health sciences.
The 12-Item General Health Questionnaire (GHQ-12): reliability, external validity and factor structure in the Spanish population.
The purpose of this study was to analyze the internal consistency and the external and structure validity of the 12-Item General Health Questionnaire (GHQ-12) in the Spanish general population. A stratified sample of 1001 subjects, ages between 25 and 65 years, taken from the general Spanish population was employed. The GHQ-12 and the Inventory of Situations and Responses of Anxiety-ISRA were administered. A Cronbach's alpha of .76 (Standardized Alpha: .78) and a 3-factor structure (with oblique rotation and maximum likelihood procedure) were obtained. External validity of Factor I (Successful Coping) with the ISRA is very robust (.82; Factor II, .70; Factor III, .75). The GHQ-12 shows adequate reliability and validity in the Spanish population. Therefore, the GHQ-12 can be used with efficacy to assess people's overall psychological well-being and to detect non-psychotic psychiatric problems. Additionally, our results confirm that the GHQ-12 can best be thought of as a multidimensional scale that assesses several distinct aspects of distress, rather than just a unitary screening measure. PMID:18940092
Sánchez-López, María del Pilar; Dresch, Virginia
Finite-Mixture Structural Equation Models for Response-Based Segmentation and Unobserved Heterogeneity
Two endemic problems face researchers in the social sciences (e.g., Marketing, Economics, Psychology, and Finance): unobserved heterogeneity and measurement error in data. Structural equation modeling is a powerful tool for dealing with these difficulties using a simultaneous equation framework with unobserved constructs and manifest indicators which are error-prone. When estimating structural equation models, however, researchers frequently treat the data as
Kamel Jedidi; Harsharanjeet S. Jagpal; Wayne S. DeSarbo
Elasto-Visco-Plastic Constitutive Equations for Quasi-Static Structures Calculations.
The development of elasto-visco-plastic constitutive equations for quasi-static structures calculations is discussed. The equations are verified for the stable materials used in mechanical construction and are extended to conditions of varying temperature...
J. Lemaitre
Equation of State of Structured Matter at Finite Temperature
We investigate the properties of nuclear matter at the first-order phase transitions such as liquid-gas phase transition and hadron-quark phase transition. As a general feature of the first-order phase transitions of matter consisting of many species of charged particles, there appears a mixed phases with geometrical structures called ``pasta'' due to the balance of the Coulomb repulsion and the surface tension between two phases [G.~D.~Ravenhall, C.~J.~Pethick and J.~R.~Wilson, Phys. Rev. Lett. 50 (1983), 2066. M.~Hashimoto, H.~Seki and M.~Yamada, Prog. Theor. Phys. 71 (1984), 320.] The equation of state (EOS) of mixed phase is different from the one obtained by a bulk application of the Gibbs conditions or by the Maxwell construction due to the effects of the non-uniform structure. We show that the charge screening and strong surface tension make the EOS close to that of the Maxwell construction. The thermal effects are elucidated as well as the above finite-size effects.
Maruyama, T.; Yasutake, N.; Tatsumi, T.
The Effects of Parceling Unidimensional Scales on Structural Parameter Estimates in Structural Equation Modeling
Structural equation modeling allows several methods of estimating the disattenuated association between 2 or more latent variables (i.e., the measurement model). In one common approach, measurement models are specified using item parcels as indicators of latent constructs. Item parcels versus original items are often used as indicators in these…
Sass, Daniel A.; Smith, Philip L.
Factor structure and reliability of the childhood trauma questionnaire and prevalence estimates of trauma for male and female street youth.
This study examines the psychometric properties of the Childhood Trauma Questionnaire short form (CTQ-SF) with street youth who have run away or been expelled from their homes (N = 397). Internal reliability coefficients for the five clinical scales ranged from .65 to .95. Confirmatory Factor Analysis (CFA) was used to test the five-factor structure of the scales yielding acceptable fit for the total sample. Additional multigroup analyses were performed to consider items by gender. Results provided only evidence of weak factorial invariance. Constrained models showed invariance in configuration, factor loadings, and factor covariances but failed for equality of intercepts. Mean trauma scores for street youth tended to fall in the moderate to severe range on all abuse/neglect clinical scales. Females reported higher levels of abuse and neglect. Prevalence of child maltreatment of individual forms was very high with 98% of street youth reporting one or more forms; 27.4% of males and 48.9% of females reported all five forms. Results of this study support the viability of the CTQ-SF for screening maltreatment in a highly vulnerable street population. Caution is recommended when comparing prevalence estimates for male and female street youth given the failure of the strong factorial multigroup model. PMID:21810791
Forde, David R; Baron, Stephen W; Scher, Christine D; Stein, Murray B
The Rivermead Post Concussion Symptoms Questionnaire
Objective To investigate the factor structure of the Rivermead Post Concussion Symptoms Questionnaire (RPQ) among individuals seen as\\u000a part of routine follow-up following traumatic brain injury.\\u000a \\u000a \\u000a \\u000a Methods RPQ data from 168 participants was examined (mean age 35.2, SD 14.3; 89% with post traumatic amnesia duration < 24 hours)\\u000a six months after admission to an Accident & Emergency Department following TBI. Structural equation modelling was
Seb Potter; Eleanor Leigh; Derick Wade; Simon Fleminger
Structural equation modeling of pesticide poisoning, depression, safety, and injury.
The role of pesticide poisoning in risk of injuries may operate through a link between pesticide-induced depressive symptoms and reduced engagement in safety behaviors. The authors conducted structural equation modeling of cross-sectional data to examine the pattern of associations between pesticide poisoning, depressive symptoms, safety knowledge, safety behaviors, and injury. Interviews of 1637 Colorado farm operators and their spouses from 964 farms were conducted during 1993-1997. Pesticide poisoning was assessed based on a history of ever having been poisoned. The Center for Epidemiologic Studies-Depression scale was used to assess depressive symptoms. Safety knowledge and safety behaviors were assessed using ten items for each latent variable. Outcomes were safety behaviors and injuries. A total of 154 injuries occurred among 1604 individuals with complete data. Pesticide poisoning, financial problems, health, and age predicted negative affect/somatic depressive symptoms with similar effect sizes; sex did not. Depression was more strongly associated with safety behavior than was safety knowledge. Two safety behaviors were significantly associated with an increased risk of injury. This study emphasizes the importance of financial problems and health on depression, and provides further evidence for the link between neurological effects of past pesticide poisoning on risk-taking behaviors and injury. PMID:24125049
Beseler, Cheryl L; Stallones, Lorann
Evaluation of model fit in nonlinear multilevel structural equation modeling
Evaluating model fit in nonlinear multilevel structural equation models (MSEM) presents a challenge as no adequate test statistic is available. Nevertheless, using a product indicator approach a likelihood ratio test for linear models is provided which may also be useful for nonlinear MSEM. The main problem with nonlinear models is that product variables are non-normally distributed. Although robust test statistics have been developed for linear SEM to ensure valid results under the condition of non-normality, they have not yet been investigated for nonlinear MSEM. In a Monte Carlo study, the performance of the robust likelihood ratio test was investigated for models with single-level latent interaction effects using the unconstrained product indicator approach. As overall model fit evaluation has a potential limitation in detecting the lack of fit at a single level even for linear models, level-specific model fit evaluation was also investigated using partially saturated models. Four population models were considered: a model with interaction effects at both levels, an interaction effect at the within-group level, an interaction effect at the between-group level, and a model with no interaction effects at both levels. For these models the number of groups, predictor correlation, and model misspecification was varied. The results indicate that the robust test statistic performed sufficiently well. Advantages of level-specific model fit evaluation for the detection of model misfit are demonstrated.
Schermelleh-Engel, Karin; Kerwer, Martin; Klein, Andreas G.
Structural Equation Modeling for Analyzing Erythrocyte Fatty Acids in Framingham
Research has shown that several types of erythrocyte fatty acids (i.e., omega-3, omega-6, and trans) are associated with risk for cardiovascular diseases. However, there are complex metabolic and dietary relations among fatty acids, which induce correlations that are typically ignored when using them as risk predictors. A latent variable approach could summarize these complex relations into a few latent variable scores for use in statistical models. Twenty-two red blood cell (RBC) fatty acids were measured in Framingham (N = 3196). The correlation matrix of the fatty acids was modeled using structural equation modeling; the model was tested for goodness-of-fit and gender invariance. Thirteen fatty acids were summarized by three latent variables, and gender invariance was rejected so separate models were developed for men and women. A score was developed for the polyunsaturated fatty acid (PUFA) latent variable, which explained about 30% of the variance in the data. The PUFA score included loadings in opposing directions among three omega-3 and three omega-6 fatty acids, and incorporated the biosynthetic and dietary relations among them. Whether the PUFA factor score can improve the performance of risk prediction in cardiovascular diseases remains to be tested.
Pottala, James V.; Djira, Gemechis D.; Espeland, Mark A.; Larson, Martin G.; Harris, William S.
The Strengths and Difficulties Questionnaire in the Bergen Child Study: A Conceptually and Methodically Motivated Structural Analysis
Objective: To test Goodman's theoretical 5-factor model of the Strengths and Difficulties Questionnaire (SDQ) in an analysis of the Norwegian parent (P) and teacher (T) versions of the questionnaire. Method: The T-SDQ was analyzed for 8,999 (95.4% of all) children in primary school grades 2-4 in Bergen, Norway, whereas the P-SDQ was examined for…
Sanne, Bjarte; Torsheim, Torbjorn; Heiervang, Einar; Stormark, Kjell Morten
A Test and Cross-Validation of the Revised Two-Factor Study Process Questionnaire Factor Structure among Western University Students
The Revised Two-Factor Study Process Questionnaire (R-SPQ-2F) is a measure of university students' approach to learning. Original evaluation of the scale's psychometric properties was based on a sample of Hong Kong university students' scores. The purpose of this study was to test and cross-validate the R-SPQ-2F factor structure, based on separate…
Immekus, Jason C.; Imbrie, P. K.
Factor Structure of the Reactive-Proactive Aggression Questionnaire in Turkish Children and Gender, Grade-Level, and Socioeconomic Status Differences in Reactive and Proactive Aggression
The present study aimed to evaluate the factor structure of the Reactive-Proactive Aggression Questionnaire (RPQ) with Turkish children, and to investigate gender, grade-level, and socioeconomic status (SES) differences in reactive and proactive aggression. Participants consisted of 1,081 Turkish children (544 boys and 537 girls) aged 9 to 14…
Uz Bas, Asli; Yurdabakan, Irfan
Adjustment to College as Measured by the Student Adaptation to College Questionnaire: A Quantitative Review of Its Structure and Relationships with Correlates and Consequences
This paper presents a meta-analytic review (k = 237, N = 44,668) of the adjustment to college literature. The review, based on studies using the Student Adaptation to College Questionnaire, is organized around three primary themes: (1) the structure of students' adjustment to college, (2) the relationship of adjustment to college constructs with…
Crede, Marcus; Niehorster, Sarah
The impact of culture and employee-focused criteria on productivity: A structural equation modelling approach
Culture and employee-focused criteria are important factors for the success of any organization. These factors have to be aligned with the productivity initiatives in the organization in order to gear ahead for excellence. Therefore, this article investigated the impact of culture and employee-focused criteria on productivity in Higher Education Institutions (HEIs) in Malaysia using intangible indicators through core values. The hypothesized relationship was tested using Structural Equation Modeling (SEM) with the PLS estimation technique. 429 questionnaires were returned from the target population. The results of the modelling revealed that the PLS estimation confirmed all the hypotheses tested as in the hypothesized model. The results generally support significant relationships between culture values, employee-focused values and productivity-focused values. The study also confirmed the mediating role of employee-focused values for the relationship between culture values and productivity-focused values. In conclusion, the empirically validated results supported the adequacy of the hypothezised model of the impact of culture and employee-focused criteria on productivity in HEI through value-based indicators.
Ab Hamid, Mohd Rashid; Mustafa, Zainol; Mohd Suradi, Nur Riza; Idris, Fazli; Abdullah, Mokhtar
[Antecedents and consequences of workplace bullying: a longitudinal analysis with a structural equation model].
Most studies focusing on the antecedents and consequences of workplace bullying have used a cross-sectional design, which impedes determining the causality of the relationships. In the present work, we analyzed, by means of structural equation models, the relationship between workplace bullying and some variables that are considered antecedents (interpersonal conflicts, role ambiguity, role conflict, and workplace social support) or consequences (health complaints and inclination to absenteeism from work) of this phenomenon. Multicenter study with two phases. The sample consisted of 696 employees from 66 centers. Workplace bullying was assessed by means of the "Mobbing-UNIPSICO" questionnaire, and the other variables with frequency scales. The cross-sectional models indicated a significant association between role conflict, workplace social support, and workplace bullying in both study periods. Concerning the longitudinal relationships, only workplace social support was a significant predictor of workplace bullying, which, in turn, was a cross-sectional and longitudinal predictor of workers' health complaints. Our results show the mediating effect of workplace bullying between certain work conditions and health complaints, and it is recommendable to replicate these findings in a multi-occupational sample. PMID:22047848
Carretero Domínguez, Noelia; Gil-Monte, Pedro Rafael; Luciano Devis, Juan Vicente
Hydrodynamic Structure of the Augmented Born-Infeld Equations
The Born-Infeld system is a nonlinear version of Maxwell's equations. We first show that, by using the energy density and the Poynting vector as additional unknown variables, the BI system can be augmented as a 10×10 system of hyperbolic conservation laws. The resulting augmented system has some similarity with magnetohydrodynamics (MHD) equations and enjoys remarkable properties (existence of a convex
Yann Brenier
Hamiltonian structure of propagation equations for ultrashort optical pulses
A Hamiltonian framework is developed for a sequence of ultrashort optical pulses propagating in a nonlinear dispersive medium. To this end a second-order nonlinear wave equation for the electric field is transformed into a first-order propagation equation for a suitably defined complex electric field. The Hamiltonian formulation is then introduced in terms of normal variables, i.e., classical complex fields referring
Sh. Amiranashvili; A. Demircan
Evaluation of Structural Equation Mixture Models: Parameter Estimates and Correct Class Assignment
Structural equation mixture models (SEMMs) are latent class models that permit the estimation of a structural equation model within each class. Fitting SEMMs is illustrated using data from 1 wave of the Notre Dame Longitudinal Study of Aging. Based on the model used in the illustration, SEMM parameter estimation and correct class assignment are…
Tueller, Stephen; Lubke, Gitta
Bayesian nonlinear structural equation modeling for hierarchical validation of dynamical systems
This paper presents a new Bayesian nonlinear structural equation modeling approach to hierarchical model assessment of dynamic systems, considering uncertainty in both predicted and measured time series data. A generalized structural equation modeling with nonlinear latent variables is presented to model two sets of relationships in multivariate hierarchical model assessment, namely, the computational model to system-level data, and low-level data
Xiaomo Jiang; Sankaran Mahadevan; Angel Urbina
Finite symmetry transformation group and localized structures of the (2+1)-dimensional coupled Burgers equation
In this paper, the finite symmetry transformation group of the (2+1)-dimensional coupled Burgers equation is studied by the modified direct method, and with the help of the truncated Painlevé expansion approach, some special localized structures for the (2+1)-dimensional coupled Burgers equation are obtained, in particular, the dromion-like and solitoff-like structures.
Lei, Ya; Yang, Duo
Maximum Likelihood Analysis of Nonlinear Structural Equation Models with Dichotomous Variables
In this article, a maximum likelihood approach is developed to analyze structural equation models with dichotomous variables that are common in behavioral, psychological and social research. To assess nonlinear causal effects among the latent variables, the structural equation in the model is defined by a nonlinear function. The basic idea of the…
Song, Xin-Yuan; Lee, Sik-Yum
Applications of structural equation modeling in marketing and consumer research: A review
This paper reviews prior applications of structural equation modeling in four major marketing journals (the Journal of Marketing, Journal of Marketing Research, International Journal of Research in Marketing, and the Journal of Consumer Research) between 1977 and 1994. After documenting and characterizing the number of applications over time, we discuss important methodological issues related to structural equation modeling and assess
Hans Baumgartner; Christian Homburg
Latent variables and structural equation models for longitudinal relationships: an illustration in nutritional epidemiology
BACKGROUND: The use of structural equation modeling and latent variables remains uncommon in epidemiology despite its potential usefulness. The latter was illustrated by studying cross-sectional and longitudinal relationships between eating behavior and adiposity, using four different indicators of fat mass. METHODS: Using data from a longitudinal community-based study, we fitted structural equation models including two latent variables (respectively baseline adiposity
Michel Chavance; Sylvie Escolano; Monique Romon; Arnaud Basdevant; Blandine de Lauzon-Guillain; Marie Aline Charles
Sensitivity analysis of Lyapunov and Riccati equations with application to controls-structures integrated design
Controls-structure integrated design is a complicated multidisciplinary design optimization problem which involves the state equations pertaining to open-loop eigenvalues and control laws. In order to alleviate the intensity of the computation, this study uses the adjoint variable method to derive sensitivity equations for the eigenvalue, Liapunov, and Riccati equations. These individual sensitivity equations are then combined together to form the multidisciplinary sensitivity equations for the control structure integrated design problems. A set of linear sensitivity equations, proportional in number to the number of performance functions involved in the optimization process, are solved. This proposed approach may provide a great saving in computer resources. The validity of the newly developed sensitivity equations is verified by numerical examples.
Hou, Gene; Koganti, Gopichand
Fixed- and random-effects meta-analytic structural equation modeling: examples and analyses in R.
Meta-analytic structural equation modeling (MASEM) combines the ideas of meta-analysis and structural equation modeling for the purpose of synthesizing correlation or covariance matrices and fitting structural equation models on the pooled correlation or covariance matrix. Cheung and Chan (Psychological Methods 10:40-64, 2005b, Structural Equation Modeling 16:28-53, 2009) proposed a two-stage structural equation modeling (TSSEM) approach to conducting MASEM that was based on a fixed-effects model by assuming that all studies have the same population correlation or covariance matrices. The main objective of this article is to extend the TSSEM approach to a random-effects model by the inclusion of study-specific random effects. Another objective is to demonstrate the procedures with two examples using the metaSEM package implemented in the R statistical environment. Issues related to and future directions for MASEM are discussed. PMID:23807765
Cheung, Mike W-L
Factor Structure and Reliability of the 2008 and 2009 SERU/UCUES Questionnaire Core. SERU Project Technical Report
This technical report summarizes the third independent factor analysis of the SERU/UCUES questionnaire responses of students with majors. The 2009 solution employed the same quantitative analysis used in the prior solutions--varimax orthogonal rotation to determine principal components followed by promax oblique rotation to identify…
Chatman, Steve
The Prospective and Retrospective Memory Questionnaire (PRMQ): Normative data and latent structure in a large non-clinical sample
The Prospective and Retrospective Memory Questionnaire (PRMQ; Smith, Della Sala, Logie, & Maylor, 2000) was developed to provide a self-report measure of prospective and retrospective memory slips in everyday life. It consists of sixteen items, eight asking about prospective memory failures, and eight concerning retrospective failures. The PRMQ was administered to a sample of the general adult population (N =
John Crawford; Geoff Smith; Elizabeth Maylor; Sergio Della Sala; Robert Logie
Joint Factor Structure of the Multidimensional Personality Questionnaire and the MMPI in a Psychiatric and High-Risk Sample
This study assessed aspects of the construct validity of the Multidimensional Personality Questionnaire (MPQ), a measure of normal personality characteristics, in a clinically relevant sample through joint factor analyses of primary and second-order scales of the MPQ and the Minnesota Multiphasic Personality Inventory (MMPI). A subsample from the Washington University Twin Study of Psychopathology was analyzed. The MPQ's primary scales
David L. DiLalla; Irving I. Gottesman; Gregory Carey; George P. Vogler
A Hamiltonian framework is developed for a sequence of ultrashort optical pulses propagating in a nonlinear dispersive medium. To this end a second-order nonlinear wave equation for the electric field is transformed into a first-order propagation equation for a suitably defined complex electric field. The Hamiltonian formulation is then introduced in terms of normal variables, i.e., classical complex fields referring to the quantum creation and annihilation operators. The derived z-propagated Hamiltonian accounts for forward and backward waves, arbitrary medium dispersion, and four-wave mixing processes. As a simple application we obtain integrals of motion for the pulse propagation. The integrals reflect time-averaged fluxes of energy, momentum, and photons transferred by the pulse. Furthermore, pulses in the form of stationary nonlinear waves are considered. They yield extremal values of the momentum flux for a given energy flux. Simplified propagation equations are obtained by reduction of the Hamiltonian. In particular, the complex electric field reduces to an analytic signal for the unidirectional propagation. Solutions of the full bidirectional model are numerically compared to the predictions of the simplified equation for the analytic signal and to the so-called forward Maxwell equation. The numerics is effectively tested by examining the conservation laws.
Amiranashvili, Sh.; Demircan, A. [Weierstrass Institute for Applied Analysis and Stochastics, Mohrenstrasse 39, D-10117 Berlin (Germany)
The feeding practices and structure questionnaire: construction and initial validation in a sample of Australian first-time mothers and their 2-year olds
Background Early feeding practices lay the foundation for children's eating habits and weight gain. Questionnaires are available to assess parental feeding but overlapping and inconsistent items, subscales and terminology limit conceptual clarity and between study comparisons. Our aim was to consolidate a range of existing items into a parsimonious and conceptually robust questionnaire for assessing feeding practices with very young children (<3 years). Methods Data were from 462 mothers and children (age 21–27 months) from the NOURISH trial. Items from five questionnaires and two study-specific items were submitted to a priori item selection, allocation and verification, before theoretically-derived factors were tested using Confirmatory Factor Analysis. Construct validity of the new factors was examined by correlating these with child eating behaviours and weight. Results Following expert review 10 factors were specified. Of these, 9 factors (40 items) showed acceptable model fit and internal reliability (Cronbach's ?: 0.61-0.89). Four factors reflected non-responsive feeding practices: 'Distrust in Appetite', 'Reward for Behaviour', 'Reward for Eating', and 'Persuasive Feeding'. Five factors reflected structure of the meal environment and limits: 'Structured Meal Setting', 'Structured Meal Timing', 'Family Meal Setting', 'Overt Restriction' and 'Covert Restriction'. Feeding practices generally showed the expected pattern of associations with child eating behaviours but none with weight. Conclusion The Feeding Practices and Structure Questionnaire (FPSQ) provides a new reliable and valid measure of parental feeding practices, specifically maternal responsiveness to children's hunger/satiety signals facilitated by routine and structure in feeding. Further validation in more diverse samples is required.
Background The level of expressed emotion (LEE) is a four-factor questionnaire that measures expressed emotion (EE) as perceived by the\\u000a recipient. These factors are: perceived lack of emotional support, perceived intrusiveness, perceived irritation, and perceive\\u000a criticism. The four factors of the LEE has previously been found to be related to psychological disorders and has good psychometric\\u000a properties for adults. However, it
William W. Hale; Quinten A. W. Raaijmakers; Coby Gerlsma; Wim Meeus
Localized Coherent Structures in (2+1)-Dimensional Generalized Nizhnik-Novikov-Veselov Equations
In this paper, a variable separation approach is used to study the localized coherent structures of the (2+1)-dimensional generalized Nizhnik-Novikov-Veselov (GNNV) equation. The abundance of the localized structures of the model is introduced by the entrance of two variables separated arbitrary functions. For some special selections of the arbitrary functions, it is shown that the localized structures of the GNNV equation may be dromions, breathers, instantons and ring solitons etc.
Ruan, Hang-Yu; Chen, Yi-Xin
Convergence analysis of structure - preserving doubling algo - rithms for Riccati - type matrix equations
Abstract. In this paper, we introduce the doubling transformation, a structure-preserving transformation for symplectic pencils, and present its basic properties. Based on these properties, a unified convergence theory for the structure-preserving doubling algorithms for a class of Riccati-type matrix equations is established, using only elementary matrix theory. Key words. matrix equation, structure-preserving doubling algorithm, convergence rate AMS subject classifications. 15A24,
W. W Lin; S. F Xu
Evaluation of Existing Structure and Civil Protection Management Framework in Greek Local Authorities: A Questionnaire Survey Demonstrates Why Prevention Fails
In the face of a growing number of natural disasters and the increasing costs associated with them, Europe and Greece in particular, have devoted significant efforts and resources in natural hazards mitigation during the last decades. Despite the significant legislative efforts (e.g. 1998/22/EC, 2001/792/EC, 2007/60/EC Directives, 3013/2002 Act) and even though a number of steps has been taken towards improving civil protection, recent catastrophic events have illustrated the weaknesses of current approaches. In particular, in Greece, events such as the 1999 Athens earthquake, the 2007 and 2009 wildfires have shown the inadequacy of prevention and mitigation practices. Given the enhanced civil protection responsibilities, given by the Greek national law (Acts 3013/2002, 3852/2010) to local authorities in Greece, this work analyses and evaluates the existing structure and current management framework under which local authorities function and examines their risk mitigation practices. We conducted the largest questionnaire survey regarding Civil Protections issues, among the municipalities of Greece. To this aim, this work used a innovative online tool to assess current framework. Therefore, a network connecting civil protection departments of municipalities was developed, based on an Internet platform that acted also as a communication tool. Overall, we had feedback either online or offline from 125 municipalities across the country (representing more than one/third of the total municipalities of Greece). Through this network, municipal civil protection officials completed surveys designed to obtain and quantify information on several aspects of civil protection practices and infrastructure. In particular, the examined factors included: (i) personnel and equipment, (ii) inter-agency cooperation, (iii) training, (iv) compliance with existing regulations and (v) persistent problems encountered by civil protection departments, that prevent the effectiveness of current practices. Responses showed that civil protection personnel lack adequate training and expertise, many are overstretched with several duties, while several prevention actions are carried out by seasonal or voluntary staff. Approximately half of the heads of civil protection offices do not hold a university degree, only 27% have a relevant scientific background (geoscientists or engineers) and more than half of them are elected members and not permanent staff, implying that no continuity is secured. Inter-agency cooperation is shown to be poor and organizational learning from international practices not adequate. Half of the municipalities report that the authorization processes are too slow so that prevention actions particularly regarding forest fires are severely delayed. Existing regulations are not followed by a significant portion of municipalities since 19% have not established a civil protection office and 23% have not compiled an action plan yet. Existing action plans lack important information, present no spatial data and are predominantly catalogues and tables of information regarding authorised personnel and equipment. Overall, underfunding, poor coordination of the different actors involved, lack of training and understaffing, lack of proper equipment and several other issues are held responsible by officials for preventing effectiveness of current practices. Finally, the EU emergency number 112 is widely unknown (87%). This work was held under the LIFE+ project "Local Authorities Alliance for Forest Fire Prevention - LIFE08/ENV/GR/000553" which is implemented with the contribution of the LIFE financial instrument of the European Community.
Papanikolaou, Dimitrios; Papanikolaou, Ioannis; Diakakis, Michalis; Deligiannakis, Georgios
Canonical Structure and Symmetries of the Schlesinger Equations
The Schlesinger equations S\\u000a (n,m) describe monodromy preserving deformations of order m Fuchsian systems with n + 1 poles. They can be considered as a family of commuting time-dependent Hamiltonian systems on the direct product of n copies of m × m matrix algebras equipped with the standard linear Poisson bracket. In this paper we present a new canonical Hamiltonian formulation\\u000a of the
Boris Dubrovin; Marta Mazzocco
We study the solvability of the Cauchy problem for the nonlinear parabolic equation @u @t =d iv (u m 1ru) when m< 0i nR2 ,w ithu(x; 0) = f(x) a given nonnegative function. It is known from earlier works of the authors that the asymptotic radial growth r 2=1 m, r =jxj for the spherical averages of f(x )i s
Singular Structure in the 3D Incompressible Euler Equations
Numerical evidence consistent with analytic bounds on singular behavior in the three-dimensional incompressible Euler equations is presented^1. Then, how this might be related to viscous, turbulent dynamics is discussed. For Euler, besides strong agreement with well-known bounds on the peak, local vorticity and strain, strong numerical evidence consistent with a blowup in the global enstrophy production is shown. All of
Robert Kerr
System Characteristics, Satisfaction and E-Learning Usage: A Structural Equation Model (SEM)
With the advent of the Internet, more and more public universities in Malaysia are putting in effort to introduce e-learning in their respective universities. Using a structured questionnaire derived from the literature, data was collected from 250 undergraduate students from a public university in Penang, Malaysia. Data was analyzed using AMOS…
Ramayah, T.; Lee, Jason Wai Chow
On the coherent structures of the Nizhnik-Novikov-Veselov equation
A variable separation approach is used to obtain exact solutions of high-dimensional nonlinear physical models. Taking the Nizhnik-Novikov-Veselov (NNV) equation as a simple example, we show that a high-dimensional nonlinear physical model may have quite rich localized coherent structures. For the NNV equation, the richness of the localized structures caused by the entrance of two variable-separated arbitrary functions. For some special selections of the arbitrary functions, it is shown that the localized structures of the NNV equation may be dromions, lumps, breathers, instantons and ring solitons, etc.
Lou, Sen-yue
Relationship between HIV/AIDS knowledge and attitude among student nurses: a structural equation model.
With the rising incidence of HIV/AIDS in China, nurses will increasingly be caring for patients with HIV/AIDS. Thus, it is necessary that they have enough knowledge to reduce the risk of occupationally acquired HIV infection and that they change their attitude to care for HIV/AIDS patients. The objective of this study is to explore the relationship between student nurses' HIV/AIDS knowledge and their attitude using a structural equation model (SEM). A cross-sectional survey was conducted in January 2008 among 528 student nurses at the technical secondary school of the China Medical University. An SEM is proposed to determine the direction and magnitude of the interdependent effects between the latent factors. The SEM was built using LISREL version 8.5. The measurement properties of the latent factors underlying the questionnaire were based on a confirmatory factor analysis (CFA). Our results as following, HIV/AIDS knowledge and attitude may be measured by seven underlying constructs, namely, preventive knowledge, knowledge of transmission routes, specialty knowledge, knowledge of nontransmission routes, positive attitude toward HIV/AIDS, negative attitude toward HIV/AIDS, and occupational attitude. The SEM fits the data well. The interdependent relationships between these constructs identified the factors of preventive knowledge, specialty knowledge, and attitude toward HIV/AIDS as having both direct and indirect effects on occupational attitude. In conclusions, our results represent an initial effort to assess the relationship between student nurses' HIV/AIDS knowledge and their attitude toward the disease. CFA and SEM analysis have demonstrated their usefulness in evaluating multifactor complex constructs. PMID:20113151
Qu, Bo; Zhang, Yang; Guo, Haiqiang; Sun, Gao
Analysis of finite microstrip structures using an efficient implementation of the integral equation technique
An efficient numerical implementation of the integral equation technique (IE) has been developed for the analysis of the electrical characteristics of finite microstrip structures. The technique formulates a volume version of the IE for the finite dielectric objects and a standard surface IE technique for the metallic areas. The system of integral equations formulated is solved with special numerical techniques
F. Quesada Pereira; J. L. Gomez Tornero; D. Cańete Rebenaque; J. Pascual Garcia; A. Alvarez Melcon
Influence of Opal Equation of State to Interior Structure and Evolution of the Sun
It was computed the interior structure and evolution of the Sun with the OPAL equation of state during the hydrogen burning phase. Theoretical evolution calculations of solar model, starting from threshold of stability point at which gravitational and internal energy are nearly the same, were carried out using Ezer equation of state through the gravitational contraction and premain sequence. Later,
Aysen Durmus; Rikkat Civelek
Abundant exact solution structures of the Nizhnik-Novikov-Veselov equation
Using the extended homogeneous balance method, we have obtained abundant exact solution structures of a (2+1)-dimensional integrable model, the Nizhnik-Novikov-Veselov equation. By means of leading order terms analysis, the nonlinear transformations of the Nizhnik-Novikov-Veselov equation are given first and then some special types of single solitary wave solution and multisoliton-like solutions are constructed.
Zhang, Jie-fang
Variational approach to the Hamiltonian structure of a new hierarchy of nonlinear equations
We determine the symplectic Hamiltonian structure associated with the nonlinear evolution equations obtained from two new isospectral problems. We follow the method of variation with respect to the field variables. An explicit example is given to demonstrate the new class of equations that are generated.
Chowdbury, A.R.; Roy, S.
Alternative Futures for World Food in 1985. Volume 3, World GOL Model Structure and Equations.
The structure of the world grain-oilseeds-livestock (GOL) projections model is described, base period data are defined, and the 930 mathematical equations used in the model are presented. Tables of elasticities are also presented to facilitate evaluation ...
A. Rojko H. Fuchs P. O'Brien D. Regier
Enhancements of Systems Based on Bayesian Networks and Structural Equation Models for Command and Control Support.
The performed project focused on a new paradigm of planning systems that are based on a combination of Bayesian networks and structural equation models. We focused on theoretical issues that surround combining the two in a practical planning system, devel...
M. J. Druzdzel
Systems Based on Bayesian Belief Networks and Structural Equation Models for Command and Control Support.
Using Structural Equation Modeling To Test for Differential Reliability and Validity: An Empirical Demonstration.
Demonstrates empirically a structural equation modeling technique for group comparison of reliability and validity. Data, which are from a study of 495 mothers' attitudes toward pregnancy, have a one-factor measurement model and three sets of subpopulation comparisons. (SLD)
Raines-Eudy, Ruth
Approximate Confidence Interval for Difference of Fit in Structural Equation Models.
Discusses a method, based on bootstrap methodology, for obtaining an approximate confidence interval for the difference in root mean square error of approximation of two structural equation models. Illustrates the method using a numerical example. (SLD)
Raykov, Tenko
Domain Decomposition Method for Maxwell's Equations: Scattering o Periodic Structures
We present a domain decomposition approach for the computation of the electro- magnetic eld within periodic structures. We use a Schwarz method with transpar- ent boundary conditions at the interfaces of the domains. Transparent boundary conditions are approximated by the perfectly matched layer method (PML). To cope with Wood anomalies appearing in periodic structures an adaptive strategy to determine optimal
Achim Schadle; Lin Zschiedrich; Sven Burger; Roland Klose; Frank Schmidt
Neutron Star Structure and the Equation of State
The structure of neutron stars is considered from theoretical and observational perspectives. We demonstrate an important aspect of neutron star structure: the neutron star radius is primarily determined by the behavior of the pressure of matter in the vicinity of nuclear matter equilibrium density. In the event that extreme softening does not occur at these densities, the radius is virtually
J. M. Lattimer; M. Prakash
Nonlinear static and dynamic analysis of beam structures using fully intrinsic equations
Beams are structural members with one dimension much larger than the other two. Examples of beams include propeller blades, helicopter rotor blades, and high aspect-ratio aircraft wings in aerospace engineering; shafts and wind turbine blades in mechanical engineering; towers, highways and bridges in civil engineering; and DNA modeling in biomedical engineering. Beam analysis includes two sets of equations: a generally linear two-dimensional problem over the cross-sectional plane and a nonlinear, global one-dimensional analysis. This research work deals with a relatively new set of equations for one-dimensional beam analysis, namely the so-called fully intrinsic equations. Fully intrinsic equations comprise a set of geometrically exact, nonlinear, first-order partial differential equations that is suitable for analyzing initially curved and twisted anisotropic beams. A fully intrinsic formulation is devoid of displacement and rotation variables, making it especially attractive because of the absence of singularities, infinite-degree nonlinearities, and other undesirable features associated with finite rotation variables. In spite of the advantages of these equations, using them with certain boundary conditions presents significant challenges. This research work will take a broad look at these challenges of modeling various boundary conditions when using the fully intrinsic equations. Hopefully it will clear the path for wider and easier use of the fully intrinsic equations in future research. This work also includes application of fully intrinsic equations in structural analysis of joined-wing aircraft, different rotor blade configuration and LCO analysis of HALE aircraft.
Sotoudeh, Zahra
On the structure of nonlinear constitutive equations for fiber reinforced composites
The structure of constitutive equations for nonlinear multiaxial behavior of transversely isotropic fiber reinforced metal matrix composites subject to proportional loading was investigated. Results from an experimental program were combined with numerical simulations of the composite behavior for complex stress to reveal the full structure of the equations. It was found that the nonlinear response can be described by a quadratic flow-potential, based on the polynomial stress invariants, together with a hardening rule that is dominated by two different hardening mechanisms.
Jansson, Stefan
Use of Prior Knowledge in a Non-Gaussian Method for Learning Linear Structural Equation Models
\\u000a We discuss causal structure learning based on linear structural equation models. Conventional learning methods most often\\u000a assume Gaussianity and create many indistinguishable models. Therefore, in many cases it is difficult to obtain much information\\u000a on the structure. Recently, a non-Gaussian learning method called LiNGAM has been proposed to identify the model structure\\u000a without using prior knowledge on the structure. However,
Takanori Inazumi; Shohei Shimizu; Takashi Washio
Comparing Empirical Power of Multilevel Structural Equation Models and Hierarchical Linear Models: Understanding Cross-Level Interactions
Both structural equation models and hierarchical linear models (HLMs) have been commonly used in multilevel analysis. This study utilized simulated data to investigate the power difference among 3 multilevel models: HLM, deviation structural equation models, and a hybrid approach of HLM and structural equation models. Two factors were examined:…
Zhang, Duan; Willson, Victor L.
Inverse diffraction grating of Maxwell's equations in biperiodic structures.
Consider a time-harmonic electromagnetic plane wave incident on a perfectly conducting biperiodic surface (crossed grating). The diffraction is modeled as a boundary value problem for the three-dimensional Maxwell equation. The surface is assumed to be a small and smooth deformation of a planar surface. In this paper, a novel approach is developed to solve the inverse diffraction grating problem in the near-field regime, which is to reconstruct the surface with resolution beyond Rayleigh's criterion. The method requires only a single incident field with one polarization, one frequency, and one incident direction, and is realized by using the fast Fourier transform. Numerical results show that the method is simple, efficient, and stable to reconstruct biperiodic surfaces with subwavelength resolution. PMID:24663798
Bao, Gang; Cui, Tao; Li, Peijun
Generalized pulse equations for through-transmission evaluation of arbitrary multilayered structures
Generalized transit-time and pulse-amplitude equations have been derived for modeling the ultrasonic through-transmission wave propagation of an arbitrary n-layered structure. The equations can be programmed into an expert system and used to identify and predict the through-transmission pulse signals from the critical interfaces of a multilayered structure. To test the formulas, the through-transmission responses from one- and three-layered configurations were measured in the laboratory and compared with computer-generated data that were determined using the derived equations. The results verify the validity of the formulas.
Chern, E. James; Nielsen, Hatsumi T. C.
A homotopy algorithm for synthesizing robust controllers for flexible structures via the maximum entropy design equations
One well known deficiency of LQG compensators is that they do not guarantee any measure of robustness. This deficiency is especially highlighted when considering control design for complex systems such as flexible structures. There has thus been a need to generalize LQG theory to incorporate robustness constraints. Here we describe the maximum entropy approach to robust control design for flexible structures, a generalization of LQG theory, pioneered by Hyland, which has proved useful in practice. The design equations consist of a set of coupled Riccati and Lyapunov equations. A homotopy algorithm that is used to solve these design equations is presented.
Collins, Emmanuel G., Jr.; Richter, Stephen
The Survey Questionnaire
Internet-based surveys are still relatively new, and researchers are just beginning to articulate best practices for questionnaire design. Online questionnaire design has generally been guided by the principles applying to other self-administered instruments, such as paper-based questionnaires. Web-based questionnaires, however, have the potential…
Ritter, Lois A. Ed.; Sue, Valerie M., Ed.
Further insights on the French WISC-IV factor structure through Bayesian structural equation modeling.
The interpretation of the Wechsler Intelligence Scale for Children--Fourth Edition (WISC-IV) is based on a 4-factor model, which is only partially compatible with the mainstream Cattell-Horn-Carroll (CHC) model of intelligence measurement. The structure of cognitive batteries is frequently analyzed via exploratory factor analysis and/or confirmatory factor analysis. With classical confirmatory factor analysis, almost all cross-loadings between latent variables and measures are fixed to zero in order to allow the model to be identified. However, inappropriate zero cross-loadings can contribute to poor model fit, distorted factors, and biased factor correlations; most important, they do not necessarily faithfully reflect theory. To deal with these methodological and theoretical limitations, we used a new statistical approach, Bayesian structural equation modeling (BSEM), among a sample of 249 French-speaking Swiss children (8-12 years). With BSEM, zero-fixed cross-loadings between latent variables and measures are replaced by approximate zeros, based on informative, small-variance priors. Results indicated that a direct hierarchical CHC-based model with 5 factors plus a general intelligence factor better represented the structure of the WISC-IV than did the 4-factor structure and the higher order models. Because a direct hierarchical CHC model was more adequate, it was concluded that the general factor should be considered as a breadth rather than a superordinate factor. Because it was possible for us to estimate the influence of each of the latent variables on the 15 subtest scores, BSEM allowed improvement of the understanding of the structure of intelligence tests and the clinical interpretation of the subtest scores. PMID:23148651
Golay, Philippe; Reverte, Isabelle; Rossier, Jérôme; Favez, Nicolas; Lecerf, Thierry
Job characteristics, motivators and stress among information technology consultants: A structural equation modeling approach
The aim of the current study was to test a structural model of the relationship between job characteristics (job demand, job control) and perceived stress (e.g. stressed, pressed, tense) with 'motivators' (e.g. responsibility, recognition, achievement, possibility of growth) as the mediating variable. In this cross-sectional study a web-based questionnaire survey was conducted among information technology (IT) consultants in Sweden (N=167).
Lars Göran Wallgren; Jan Johansson Hanse
Bayesian analysis of two-level nonlinear structural equation models with continuous and polytomous data.
Two-level structural equation models with mixed continuous and polytomous data and nonlinear structural equations at both the between-groups and within-groups levels are important but difficult to deal with. A Bayesian approach is developed for analysing this kind of model. A Markov chain Monte Carlo procedure based on the Gibbs sampler and the Metropolis-Hasting algorithm is proposed for producing joint Bayesian estimates of the thresholds, structural parameters and latent variables at both levels. Standard errors and highest posterior density intervals are also computed. A procedure for computing Bayes factor, based on the key idea of path sampling, is established for model comparison. PMID:15171800
Structure-function hierarchies and von Kármán-Howarth relations for turbulence in magnetohydrodynamical equations.
We generalize the method of A. M. Polyakov, [ Phys. Rev. E 52 6183 (1995)] for obtaining structure-function relations in turbulence in the stochastically forced Burgers equation, to develop structure-function hierarchies for turbulence in three models for magnetohydrodynamics (MHD). These are the Burgers analogs of MHD in one dimension [ Eur. Phys. J. B 9 725 (1999)], and in three dimensions (3DMHD and 3D Hall MHD). Our study provides a convenient and unified scheme for the development of structure-function hierarchies for turbulence in a variety of coupled hydrodynamical equations. For turbulence in the three sets of MHD equations mentioned above, we obtain exact relations for third-order structure functions and their derivatives; these expressions are the analogs of the von Kármán-Howarth relations for fluid turbulence. We compare our work with earlier studies of such relations in 3DMHD and 3D Hall MHD. PMID:24580182
Basu, Abhik; Naji, Ali; Pandit, Rahul
Equation of state of nucleon matter and neutron star structure
Properties of dense nucleon matter and the structure of neutron stars are\\u000astudied using variational chain summation methods and the new Argonne v18\\u000atwo-nucleon interaction. The neutron star gravitational mass limit obtained\\u000awith this interaction is 1.67 M_{solar}. Boost corrections to the two-nucleon\\u000ainteraction, which give the leading relativistic effect of order (v\\/c)^2, as\\u000awell as three-nucleon interactions, are also
A. Akmal; V. R. Pandharipande; D. G. Ravenhall
A Stepwise Structural Equation Modeling Algorithm to Recon struct Genetic Networks
Motivation: A stepwise structural equation modeling algorithm (SSEM) has been developed to infer genetic networks from time course microarray data. Besides observed variables, SSEM also incorporates hidden variables in order to depict regulations from proteins and other molecules that are not measured by microarrays. SSEM can learn the structure of a genetic network from microarray data. We have simulated data
Grace S. Shieh; Chung-Ming Chen; Ching-Yun Yu; Juiling Huang; Woei-Fuh Wang
Multilevel Structural Equation Models for the Analysis of Comparative Data on Educational Performance
The Programme for International Student Assessment comparative study of reading performance among 15-year-olds is reanalyzed using statistical procedures that allow the full complexity of the data structures to be explored. The article extends existing multilevel factor analysis and structural equation models and shows how this can extract richer…
Goldstein, Harvey; Bonnet, Gerard; Rocher, Thierry
Introducing Algebraic Structures through Solving Equations: Vertical Content Knowledge for K-12 Mathematics Teachers
Algebraic structures are a necessary aspect of algebraic thinking for K-12 students and teachers. An approach for introducing the algebraic structure of groups and fields through the arithmetic properties required for solving simple equations is summarized; the collective (not individual) importance of these axioms as a foundation for algebraic…
Wasserman, Nicholas H.
Structural Equation Modeling in Assessing Students' Understanding of the State Changes of Matter
In this study, structural equation modeling (SEM) is applied to an instrument assessing students' understanding of the particulate nature of matter, the collective properties and physical changes, such as melting, evaporation, boiling and condensation. The structural relationships among particular groups of items were investigated. In addition,…
Stamovlasis, Dimitrios; Tsitsipis, Georgios; Papageorgiou, George
Application of partial differential equation modeling of the control/structural dynamics of flexible spacecraft
Partial differential equations for modeling the structural dynamics and control systems of flexible spacecraft are applied here in order to facilitate systems analysis and optimization of these spacecraft. Example applications are given, including the structural dynamics of SCOLE, the Solar Array Flight Experiment, the Mini-MAST truss, and the LACE satellite. The development of related software is briefly addressed.
Taylor, Lawrence W., Jr.; Rajiyah, H.
Using Mx to Analyze Cross-Level Effects in Two-Level Structural Equation Models
Two-level data sets are frequently encountered in social and behavioral science research. They arise when observations are drawn from a known hierarchical structure, such as when individuals are randomly drawn from groups that are randomly drawn from a target population. Although 2-level data analysis in the context of structural equation modeling…
Bai, Yun; Poon, Wai-Yin
Opportunities for Improving Consumer Research through Latent Variable Structural Equation Modeling
This article discusses several advantages of latent variable structural equation modeling (LVSEM), and the potential it has for solving some fundamental problems hindering research in the field. The advantages highlighted include the ability to control for measurement error; an enhanced ability to test the effects of experimental manipulations; the ability to test complex theoretical structures; the ability to link micro
OpenMx: An Open Source Extended Structural Equation Modeling Framework
OpenMx is free, full-featured, open source, structural equation modeling (SEM) software. OpenMx runs within the "R" statistical programming environment on Windows, Mac OS-X, and Linux computers. The rationale for developing OpenMx is discussed along with the philosophy behind the user interface. The OpenMx data structures are introduced--these…
Boker, Steven; Neale, Michael; Maes, Hermine; Wilde, Michael; Spiegel, Michael; Brick, Timothy; Spies, Jeffrey; Estabrook, Ryne; Kenny, Sarah; Bates, Timothy; Mehta, Paras; Fox, John
Using Structural Equation Modeling to Examine Group Differences in Assessment Booklet Designs with Sparse Data
The current research demonstrates the effectiveness of using structural equation modeling (SEM) for the investigation of subgroup differences with sparse data designs where not every student takes every item. Simulations were conducted that reflected missing data structures like those encountered in large survey assessment programs (e.g., National…
Willse, John T.; Goodman, Joshua T.; Allen, Nancy; Klaric, John
A Meta-Analytical Structural Equations Analysis of a Model of Employee Turnover
The present study combined meta-analysis with structural equations modeling (SEM) to validate Mobley, Horner, and Hollingsworth's (1978) turnover theory as well as alternative structural networks proposed by Dalessio, Silverman, and Schuck (1986), Hom, Griffeth, and Sellaro (1984), and Bannister and Griffeth (1986). We aggregated correlations from 17 studies (N = 5,013 employees), correcting for unreliability and sampling error. Then we
Peter W. Hom; Fanny Caranikas-Walker; Gregory E. Prussia; Rodger W. Griffeth
Maximum Likelihood Analysis of a Two-Level Nonlinear Structural Equation Model with Fixed Covariates
In this article, a maximum likelihood (ML) approach for analyzing a rather general two-level structural equation model is developed for hierarchically structured data that are very common in educational and/or behavioral research. The proposed two-level model can accommodate nonlinear causal relations among latent variables as well as effects…
Lee, Sik-Yum; Song, Xin-Yuan
LETTER TO THE EDITOR: Quantum algebraic structures compatible with the harmonic oscillator Newton equation
We study some of the algebraic structures that are compatible with the quantization of the harmonic oscillator through its Newton equation. Examples of such structures are given; they include undeformed and q-deformed oscillators, as well as the SU(2) and the deformed SUq(2) Lie algebras, which appear in a variety of physical models.
Arik, Metin; Atakishiyev, Natig M.; Wolf, Kurt Bernardo
Structure and thermodynamics of fluid xenon using an accurate integral equation for three-body forces
Recently, we proposed a new self-consistent integral equation to obtain the pair correlation function of simple fluids in the case of pairwise additive forces [J. Chem. Phys. 114, 4141 (2001)]. Here this integral equation is applied to predict the structural and thermodynamic properties of xenon at supercritical temperatures and low densities, with the aim of examining the possible effect of the three-body dispersion forces. The validity of our extended integral equation is tested against molecular dynamics, and the results are compared to recent small-angle neutron scattering measurements [Formisano et al. Phys. Rev. E 58, 2648 (1998)] and thermodynamic properties. The good agreement found between semianalytic calculations and simulation or experimental results of the structural and thermodynamic properties gives clear indication of the efficiency of the use of our integral equation conjugated with an effective pair potential consisting of the Aziz-Slaman two-body potential plus the Axilrod-Teller three-body potential.
Bomont, J. M.; Bretonnet, J. L.
Solution techniques for the fully discretized equations in computation of fluid–structure interactions with the space–time formulations
We provide an overview of the solution techniques we have developed for the fully discretized equations encountered at every time step in computation of fluid–structure interactions with the space–time techniques. These coupled, nonlinear equations are generated from the finite element discretization of the governing equations for the fluid mechanics, structural mechanics and the motion of the fluid mechanics mesh. The
Tayfun E. Tezduyar; Sunil Sathe; Keith Stein
It was computed the interior structure and evolution of the Sun with the OPAL equation of state during the hydrogen burning phase. Theoretical evolution calculations of solar model, starting from threshold of stability point at which gravitational and internal energy are nearly the same, were carried out using Ezer equation of state through the gravitational contraction and premain sequence. Later, during hydrogen burning phase, solar model was constructed with OPAL equation of state which was defined in the temperature range 5000 ?T ?108K. We compared our solar model with recent models computed by other groups and with helioseismic results.
Durmus, Aysen; Civelek, Rikkat
A family of solution algorithms for nonlinear structural analysis based on relaxation equations
A family of hierarchical algorithms for nonlinear structural equations are presented. The algorithms are based on the Davidenko-Branin type homotopy and shown to yield consistent hierarchical perturbation equations. The algorithms appear to be particularly suitable to problems involving bifurcation and limit point calculations. An important by-product of the algorithms is that it provides a systematic and economical means for computing the stepsize at each iteration stage when a Newton-like method is employed to solve the systems of equations. Some sample problems are provided to illustrate the characteristics of the algorithms.
Park, K. C.
A novel hierarchy of differential—integral equations and their generalized bi-Hamiltonian structures
With the aid of the zero-curvature equation, a novel integrable hierarchy of nonlinear evolution equations associated with a 3 × 3 matrix spectral problem is proposed. By using the trace identity, the bi-Hamiltonian structures of the hierarchy are established with two skew-symmetric operators. Based on two linear spectral problems, we obtain the infinite many conservation laws of the first member in the hierarchy.
Zhai, Yun-Yun; Geng, Xian-Guo; He, Guo-Liang
On the structure of balance equations and extended field theories of mechanics
Summary A new approach to thermodynamics has been proposed recently, in which, in addition to the densities of mass, momentum and\\u000a energy, the densities of momentum flux and energy flux are also taken as independent state variables. Extra equations of balance\\u000a motivated by the moment equations of the kinetic theory are postulated. In this paper, we explore the general structure of
I-Shih Liu
A New Ballistic Limit Equation of Projectiles Hypervelocity Impacting on Dual Wall Structures
The potential threat from meteoroid and orbital debris particles impacting on pressurized spacecraft prompted a study of ballistic limit equations The ballistic limits can be subdivided into three phases ballistic shatter and melt vaporization The present paper is devoted to a new ballistic limit equation of sphere projectiles impacting on dual wall structures Compared with existed equations the proposed equation has clearer theoretical bases and more convenient form for engineering design In ballistic phase forward velocity of projectiles after impacting bumpers is presented as a non-dimensional function from results of numerical simulations by a multivariate linear least squares regression analysis Materials used for bumpers in these numerical simulations consisted of aluminum copper and steel Because of little effect the spacing between the walls was not considered in ballistic phase The response of rear walls is modeled following a single wall crater equation In shatter phase the approach for obtaining the equation is similar to that in ballistic phase The forward velocity of the biggest fragments of chattered projectiles after impacting bumpers was analyzed in shatter phase In melt vaporization phase since accelerated facilities can hardly reach so high velocity experimental data are relatively less than the other two phases An initial equation form based on dynamic mechanics analysis was assumed firstly and the equation was obtained by a regression analysis for a single variable lastly Tresca criterion was used to define the critical penetration
Ding, L.; Zhang, W.; Pang, B. J.
Fluid/Structure Interaction Studies of Aircraft Using High Fidelity Equations on Parallel Computers
Abstract Aeroelasticity which involves strong coupling of fluids, structures and controls is an important element in designing an aircraft. Computational aeroelasticity using low fidelity methods such as the linear aerodynamic flow equations coupled with the modal structural equations are well advanced. Though these low fidelity approaches are computationally less intensive, they are not adequate for the analysis of modern aircraft such as High Speed Civil Transport (HSCT) and Advanced Subsonic Transport (AST) which can experience complex flow/structure interactions. HSCT can experience vortex induced aeroelastic oscillations whereas AST can experience transonic buffet associated structural oscillations. Both aircraft may experience a dip in the flutter speed at the transonic regime. For accurate aeroelastic computations at these complex fluid/structure interaction situations, high fidelity equations such as the Navier-Stokes for fluids and the finite-elements for structures are needed. Computations using these high fidelity equations require large computational resources both in memory and speed. Current conventional super computers have reached their limitations both in memory and speed. As a result, parallel computers have evolved to overcome the limitations of conventional computers. This paper will address the transition that is taking place in computational aeroelasticity from conventional computers to parallel computers. The paper will address special techniques needed to take advantage of the architecture of new parallel computers. Results will be illustrated from computations made on iPSC/860 and IBM SP2 computer by using ENSAERO code that directly couples the Euler/Navier-Stokes flow equations with high resolution finite-element structural equations.
Guruswamy, Guru; VanDalsem, William (Technical Monitor)
Progress in Computational Aeroelasticity Using High Fidelity Flow and Structural Equations on Parallel Computers
Aeroelasticity which involves strong coupling of fluids, structures and controls is an important element in designing an aircraft. Computational aeroelasticity using low fidelity methods such as the linear aerodynamic flow equations coupled with the modal structural equations are well advanced. Though these low fidelity approaches are computationally less intensive, they are not adequate for the analysis of modern aircraft such as High Speed Civil Transport (HSCT) and Advanced Subsonic Transport (AST) which can experience complex flow/structure interactions. HSCT can experience vortex induced aeroelastic oscillations whereas AST can experience transonic buffet associated structural oscillations. Both aircraft may experience a dip in the flutter speed at the transonic regime. For accurate aeroelastic computations at these complex fluid/structure interaction situations, high fidelity equations such as the Navier-Stokes for fluids and the finite-elements for structures are needed. Computations using these high fidelity equations require large computational resources both in memory and speed. Current conventional supercomputers have reached their limitations both in memory and speed. As a result, parallel computers have evolved to overcome the limitations of conventional computers. This paper will address the transition that is taking place in computational aeroelasticity from conventional computers to parallel computers. The paper will address special techniques needed to take advantage of the architecture of new parallel computers. Results will be illustrated from computations made on iPSC/860 and IBM SP2 computer by using ENASERO code that directly couples the Euler/Navier-Stokes flow equations with high resolution finite-element structural equations.
Guruswamy, Guru P.; Byun, Chansup; VanDalsem, William (Technical Monitor)
Conversion of Questionnaire Data
During the survey, respondents are asked to provide qualitative answers (well, adequate, needs improvement) on how well material control and accountability (MC&A) functions are being performed. These responses can be used to develop failure probabilities for basic events performed during routine operation of the MC&A systems. The failure frequencies for individual events may be used to estimate total system effectiveness using a fault tree in a probabilistic risk analysis (PRA). Numeric risk values are required for the PRA fault tree calculations that are performed to evaluate system effectiveness. So, the performance ratings in the questionnaire must be converted to relative risk values for all of the basic MC&A tasks performed in the facility. If a specific material protection, control, and accountability (MPC&A) task is being performed at the 'perfect' level, the task is considered to have a near zero risk of failure. If the task is performed at a less than perfect level, the deficiency in performance represents some risk of failure for the event. As the degree of deficiency in performance increases, the risk of failure increases. If a task that should be performed is not being performed, that task is in a state of failure. The failure probabilities of all basic events contribute to the total system risk. Conversion of questionnaire MPC&A system performance data to numeric values is a separate function from the process of completing the questionnaire. When specific questions in the questionnaire are answered, the focus is on correctly assessing and reporting, in an adjectival manner, the actual performance of the related MC&A function. Prior to conversion, consideration should not be given to the numeric value that will be assigned during the conversion process. In the conversion process, adjectival responses to questions on system performance are quantified based on a log normal scale typically used in human error analysis (see A.D. Swain and H.E. Guttmann, 'Handbook of Human Reliability Analysis with Emphasis on Nuclear Power Plant Applications,' NUREG/CR-1278). This conversion produces the basic event risk of failure values required for the fault tree calculations. The fault tree is a deductive logic structure that corresponds to the operational nuclear MC&A system at a nuclear facility. The conventional Delphi process is a time-honored approach commonly used in the risk assessment field to extract numerical values for the failure rates of actions or activities when statistically significant data is absent.
Powell, Danny H [ORNL] [ORNL; Elwood Jr, Robert H [ORNL] [ORNL
Confirming the Structure of the "Why Do You Smoke?" Questionnaire: A Community Resource for Adolescent Tobacco Cessation
In response to the problem of adolescent smoking and limited appropriate cessation resources, this study examined the pattern and structure of the American Lung Association, Why Do You Smoke? (WDS) to determine its appropriateness for use in youth smoking cessation programs. The WDS is used to help smokers identify primary motivations for using…
Smith, Dennis W.; Lee, Jay T.; Colwell, Brian; Stevens-Manser, Stacey
The Strengths and Difficulties Questionnaire (SDQ)--Self-Report. An Analysis of Its Structure in a Multiethnic Urban Adolescent Sample
Background: The SDQ is currently one of the internationally most frequently used screening instruments for child and adolescent mental health purposes. However, its structure, cross-cultural equivalence, and its applicability in ethnic minority groups is still a matter of discussion. Methods: SDQ self-report data of 5,379 ethnic Norwegian and 865…
Richter, Jorg; Sagatun, Ase; Heyerdahl, Sonja; Oppedal, Brit; Roysamb, Espen
Intermediate-energy-proton scattering, the Dirac equation, and nuclear structure
The Dirac equation employing an impulse approximation optical potential based on NN phase shifts has been shown to provide a description of the intermediate energy proton-nucleus spin-dependent elastic scattering data not yet found in the context of a Schrödinger approach. Using analytic methods generalized to the Dirac equation, we trace this success to the nonlinear density contributions which arise as a natural consequence of the Dirac approach. This new understanding resurrects the hope of using intermediate energy protons as a probe of nuclear structure details. NUCLEAR REACTIONS Intermediate energy. Dirac impulse approximation, Dirac-eikonal amplitude, analytic methods, the Dirac approach and nuclear structure.
Amado, R. D.; Piekarewicz, J.; Sparrow, D. A.; McNeil, J. A.
Second-order discrete Kalman filtering equations for control-structure interaction simulations
A general form for the first-order representation of the continuous, second-order linear structural dynamics equations is introduced in order to derive a corresponding form of first-order Kalman filtering equations (KFE). Time integration of the resulting first-order KFE is carried out via a set of linear multistep integration formulas. It is shown that a judicious combined selection of computational paths and the undetermined matrices introduced in the general form of the first-order linear structural systems leads to a class of second-order discrete KFE involving only symmetric, N x N solution matrix.
Park, K. C.; Belvin, W. Keith; Alvin, Kenneth F.
Thermodynamics and structure of a two-dimensional electrolyte by integral equation theory
Monte Carlo simulations and integral equation theory were used to predict the thermodynamics and structure of a two-dimensional Coulomb fluid. We checked the possibility that integral equations reproduce Kosterlitz-Thouless and vapor-liquid phase transitions of the electrolyte and critical points. Integral equation theory results were compared to Monte Carlo data and the correctness of selected closure relations was assessed. Among selected closures hypernetted-chain approximation results matched computer simulation data best, but these equations unfortunately break down at temperatures well above the Kosterlitz-Thouless transition. The Kovalenko-Hirata closure produces results even at very low temperatures and densities, but no sign of phase transition was detected.
Aupic, Jana; Urbic, Tomaz
Thermodynamics and structure of a two-dimensional electrolyte by integral equation theory.
Monte Carlo simulations and integral equation theory were used to predict the thermodynamics and structure of a two-dimensional Coulomb fluid. We checked the possibility that integral equations reproduce Kosterlitz-Thouless and vapor-liquid phase transitions of the electrolyte and critical points. Integral equation theory results were compared to Monte Carlo data and the correctness of selected closure relations was assessed. Among selected closures hypernetted-chain approximation results matched computer simulation data best, but these equations unfortunately break down at temperatures well above the Kosterlitz-Thouless transition. The Kovalenko-Hirata closure produces results even at very low temperatures and densities, but no sign of phase transition was detected. PMID:24832290
The factor structure and factorial invariance of the Pain-Coping Questionnaire across age: evidence from community-based samples of children and adults.
The Pain-Coping Questionnaire was developed for children to assess pain-coping strategies. It was originally suggested as a second-order factor measure: eight first-order factors and three higher-order factors. The main objective of this study was to investigate the psychometric properties of the PCQ when used with children and adults. Two samples of 702 children and 590 adults completed the measure. Confirmatory factor analytic procedures were used to examine the factor structure, and invariance across samples. The results provided good support for a second-order structural model of seven subscales for children, for a first-order structural model of seven subscales for adults, and for between-group invariance first-order structural model. These findings suggest that data obtained on the seven first-order factors from children are directly comparable to scores from adults. The internal consistency, criterion validity and convergent validity were also confirmed in both children and adult samples. This work also reports some preliminary findings related to sex and age differences on the use of pain-coping styles. PMID:19084438
Huguet, Anna; Miró, Jordi; Nieto, Rubén
Evaluation of structural equation mixture models Parameter estimates and correct class assignment
Structural Equation Mixture Models(SEMMs) are latent class models that permit the estimation of a structural equation model within each class. Fitting SEMMs is illustrated using data from one wave of the Notre Dame Longitudinal Study of Aging. Based on the model used in the illustration, SEMM parameter estimation and correct class assignment are investigated in a large scale simulation study. Design factors of the simulation study are (im)balanced class proportions, (im)balanced factor variances, sample size, and class separation. We compare the fit of models with correct and misspecified within-class structural relations. In addition, we investigate the potential to fit SEMMs with binary indicators. The structure of within-class distributions can be recovered under a wide variety of conditions, indicating the general potential and flexibility of SEMMs to test complex within-class models. Correct class assignment is limited.
Structure of the solution set for a class of semilinear elliptic equations with asymptotic linear nonlinearity
We consider a semilinear elliptic equation with asymptotic linear nonlinearity applying bifurcation theory and spectral analysis. We obtain the exact multiplicity of the positive solutions and a very precise structure of the solution set, which improves the previous knowledge of the problem.
Jia Duo; Junping Shi; Yuwen Wang
A Graphical Method for Assessing the Identification of Linear Structural Equation Models
A graphical method is presented for assessing the state of identifiability of the parameters in a linear structural equation model based on the associated directed graph. We do not restrict attention to recursive models. In the recent literature, methods based on graphical models have been presented as a useful tool for assessing the state of…
Eusebi, Paolo
A Bayesian Approach for Nonlinear Structural Equation Models with Dichotomous Variables Using Logit and Probit Links
Analysis of ordered binary and unordered binary data has received considerable attention in social and psychological research. This article introduces a Bayesian approach, which has several nice features in practical applications, for analyzing nonlinear structural equation models with dichotomous data. We demonstrate how to use the software…
Lee, Sik-Yum; Song, Xin-Yuan; Cai, Jing-Heng
Bayesian Methods for Analyzing Structural Equation Models with Covariates, Interaction, and Quadratic Latent Variables
The analysis of interaction among latent variables has received much attention. This article introduces a Bayesian approach to analyze a general structural equation model that accommodates the general nonlinear terms of latent variables and covariates. This approach produces a Bayesian estimate that has the same statistical optimal properties as a…
Lee, Sik-Yum; Song, Xin-Yuan; Tang, Nian-Sheng
Embedding IRT in Structural Equation Models: A Comparison with Regression Based on IRT Scores
This article reviews the problems associated with using item response theory (IRT)-based latent variable scores for analytical modeling, discusses the connection between IRT and structural equation modeling (SEM)-based latent regression modeling for discrete data, and compares regression parameter estimates obtained using predicted IRT scores and…
Lu, Irene R. R.; Thomas, D. Roland; Zumbo, Bruno D.
Linking structural equation modeling to Bayesian networks: Decision support for customer retention in virtual communities
Bayesian networks are limited in differentiating between causal and spurious relationships among decision factors. Decision making without differentiating the two relationships cannot be effective. To overcome this limitation of Bayesian networks, this study proposes linking Bayesian networks to structural equation modeling (SEM), which has an advantage in testing causal relationships between factors. The capability of SEM in empirical validation combined
Sumeet Gupta; Hee-woong Kim
Modelling functional integration: a comparison of structural equation and dynamic causal models
The brain appearsto adhere to two fundamental principles of functional organisation, functional integration and functional specialisation, where the integration within and among specialised areas is mediated by effective connectivity. In this paper, we review two different approaches to modelling effective connectivity from fMRI data, structural equation models (SEMs) and dynamic causal models (DCMs). In common to both approaches are model
W. D. Penny; K. E. Stephan; A. Mechelli; K. J. Friston
Structural Equation Modeling of Multitrait-Multimethod Data: Different Models for Different Types of Methods
The question as to which structural equation model should be selected when multitrait-multimethod (MTMM) data are analyzed is of interest to many researchers. In the past, attempts to find a well-fitting model have often been data-driven and highly arbitrary. In the present article, the authors argue that the measurement design (type of methods…
Eid, Michael; Nussbeck, Fridtjof W.; Geiser, Christian; Cole, David A.; Gollwitzer, Mario; Lischetzke, Tanja
Painleve singularity structure analysis of three component Gross-Pitaevskii type equations
In this paper, we have studied the integrability nature of a system of three-coupled Gross-Pitaevskii type nonlinear evolution equations arising in the context of spinor Bose-Einstein condensates by applying the Painleve singularity structure analysis. We show that only for two sets of parametric choices, corresponding to the known integrable cases, the system passes the Painleve test.
Kanna, T.; Sakkaravarthi, K. [Department of Physics, Bishop Heber College, Tiruchirapalli 620 017 (India); Kumar, C. Senthil [Department of Physics, VMKV Engineering College, Periaseeragapadi, Salem 636 308 (India); Lakshmanan, M. [Centre for Nonlinear Dynamics, Bharathidasan University, Tiruchirapalli 620 024 (India); Wadati, M. [Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)
On the Madness in His Method: R. B. Cattell's Contributions to Structural Equation Modeling.
The many methodological contributions of Raymond B. Cattell to multivariate analysis are discussed in terms of contemporary issues in structural equation modeling. His factor analytic approach is compared with current modeling practices. A critical evaluation finds much of Cattell's work still innovative, technically advanced, and valuable to…
McArdle, J. Jack
(Why) Should We Use SEM? Pros and Cons of Structural Equation Modeling
During the last two decades, Structural Equation Modeling (SEM) has evolved from a statistical technique for insiders to an established valuable tool for a broad scientific public. This class of analyses has much to offer, but at what price? This paper pro- vides an overview on SEM, its underlying ideas, potential applications and current software. Furthermore, it discusses avoidable pitfalls
Christof Nachtigall; Ulf Kroehne; Friedrich Funke; Rolf Steyer
A Structural Equation Test of the Value–Attitude–Behavior Hierarchy
The role of values has received limited empirical attention relative to its potential significance, especially within a causal modeling approach. A series of multivariate and structural equation analyses supported the hypotheses that values have internal and external dimensions that influence attitudes. In turn, attitudes were found to influence behaviors, as the final phase in the value—attitude—behavior hierarchy. These analyses were
Pamela M. Homer; Lynn R. Kahle
Structural Equation Modeling versus Ordinary Least Squares Canonical Analysis: Some Heuristic Comparisons.
This paper describes structural equation modeling (SEM) in comparison with another overarching analysis within the general linear model (GLM) analytic family: canonical correlation analysis. The uninitiated reader can gain an understanding of SEM's basic tenets and applications. Latent constructs discovered via a measurement model are explored and…
Dawson, Thomas E.
Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety
Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb.…
Wolf, Erika J.; Harrington, Kelly M.; Clark, Shaunna L.; Miller, Mark W.
A Polychoric Instrumental Variable (PIV) Estimator for Structural Equation Models with Categorical Variables
This paper presents a new polychoric instrumental variable (PIV) estimator to use in structural equation models (SEMs) with categorical observed variables. The PIV estimator is a generalization of Bollen's (Psychometrika 61:109-121, 1996) 2SLS/IV estimator for continuous variables to categorical endogenous variables. We derive the PIV estimator…
Bollen, Kenneth A.; Maydeu-Olivares, Albert
A structural multi-mechanism constitutive equation for cerebral arterial tissue
A structural multi-mechanism constitutive equation is developed to describe the nonlinear, anisotropic, inelastic mechanical behavior of cerebral arterial tissue. Elastin and collagen fibers are treated as separate components (mechanisms) of the artery. Elastin is responsible for load bearing at low strain levels while the collagen mechanism is recruited for load bearing at higher strain levels. This work builds on an
Dalong Li; Anne M. Robertson
Does Method of Handling Missing Data Affect Results of a Structural Equation Model?
The influence of method of handling missing data on estimates produced by a structural equation model of the effects of part-time work on high-school student achievement was investigated. Missing data methods studied were listwise deletion, pairwise deletion, the expectation maximization (EM) algorithm, regression, and response pattern. The 26…
Witta, E. Lea
Singularity-structure analysis and Hirota's bilinearisation of the Davey-Stewartson equation
The singularity-structure aspects of the Davey-Stewartson equation is investigated and it is shown that the system possesses the generalised Painleve property in the sense of Weiss, Tabor and Carnevale (1983). Further, the associated Backlund transformation in constructed and Hirota's bilinearisation is obtained straightforwardly from the Painleve analysis.
Ganesan, S.; Lakshmanan, M.
Structural Equation Models of Latent Interactions: Clarification of Orthogonalizing and Double-Mean-Centering Strategies
The purpose of this investigation is to compare a new (double-mean-centering) strategy to estimating latent interactions in structural equation models with the (single) mean-centering strategy (Marsh, Wen, & Hau, 2004, 2006) and the orthogonalizing strategy (Little, Bovaird, & Widaman, 2006; Marsh et al., 2007). A key benefit of the…
Lin, Guan-Chyun; Wen, Zhonglin; Marsh, Herbert W.; Lin, Huey-Shyan
Aero-Structural Wing Planform Optimization Using the Navier-Stokes Equations
This paper describes the formulation of optimization techniques based on control theory for wing section and planform design in viscous compressible o w modeled by the Reynolds Averaged Navier-Stokes equations. Because the two disciplines that are relevant to this problem are aerodynamics and structures, an extension of a single to a multiple objective cost function is considered. A realistic model
Kasidit Leoviriyakit; Sangho Kim; Antony Jameson
Structural Equation Modeling in Language Testing and Learning Research: A Review
Despite the recent increase of structural equation modeling (SEM) in language testing and learning research and Kunnan's (1998) call for the proper use of SEM to produce useful findings, there seem to be no reviews about how SEM is applied in these areas or about the extent to which the current application accords with appropriate practices. To…
In'nami, Yo; Koizumi, Rie
Estimation of health effects of prenatal methylmercury exposure using structural equation models
BACKGROUND: Observational studies in epidemiology always involve concerns regarding validity, especially measurement error, confounding, missing data, and other problems that may affect the study outcomes. Widely used standard statistical techniques, such as multiple regression analysis, may to some extent adjust for these shortcomings. However, structural equations may incorporate most of these considerations, thereby providing overall adjusted estimations of associations. This
Esben Budtz-Jřrgensen; Niels Keiding; Philippe Grandjean; Pal Weihe
A Robust Bayesian Approach for Structural Equation Models with Missing Data
In this paper, normal/independent distributions, including but not limited to the multivariate t distribution, the multivariate contaminated distribution, and the multivariate slash distribution, are used to develop a robust Bayesian approach for analyzing structural equation models with complete or missing data. In the context of a nonlinear…
Lee, Sik-Yum; Xia, Ye-Mao
Quasi-Maximum Likelihood Estimation of Structural Equation Models with Multiple Interaction and Quadratic Effects
In this article, a nonlinear structural equation model is introduced and a quasi-maximum likelihood method for simultaneous estimation and testing of multiple nonlinear effects is developed. The focus of the new methodology lies on efficiency, robustness, and computational practicability. Monte-Carlo studies indicate that the method is highly…
Klein, Andreas G.; Muthen, Bengt O.
A Program Implementing Mardia's Multivariate Normality Test for Use in Structural Equation Modeling with Latent Variables.
Presents KANT, a FORTRAN 77 software program that tests assumptions of multivariate normality in a data set. Based on the test developed by M. V. Mardia (1985), the KANT program is useful for those engaged in structural equation modeling with latent variables. (SLD)
MacIntosh, Randall
Self-Conscious Emotions in Response to Perceived Failure: A Structural Equation Model
This study explored the occurrence of self-conscious emotions in response to perceived academic failure among 4th-grade students from the United States and Bulgaria, and the author investigated potential contributors to such negative emotional experiences. Results from structural equation modeling indicated that regardless of country, negative…
Bidjerano, Temi
Prescriptive Statements and Educational Practice: What Can Structural Equation Modeling (SEM) Offer?
Longitudinal structural equation modeling (SEM) can be a basis for making prescriptive statements on educational practice and offers yields over "traditional" statistical techniques under the general linear model. The extent to which prescriptive statements can be made will rely on the appropriate accommodation of key elements of research design,…
Martin, Andrew J.
Self-Esteem as a Mediator Between Perfectionism and Depression: A Structural Equations Analysis
This study of college students (N = 464) examined the association between adaptive and maladaptive dimensions of perfectionism and 2 mental health outcomes (self-esteem and depression). Confirmatory factor analysis was used to develop and assess the measurement model used in this study. Structural equations modeling was used to test a mediational model derived from prior theory and research. Analyses supported
Kenneth G. Rice; Jeffrey S. Ashby; Robert B. Slaney
Fixed-Effects Meta-Analyses as Multiple-Group Structural Equation Models
Meta-analysis is the statistical analysis of a collection of analysis results from individual studies, conducted for the purpose of integrating the findings. Structural equation modeling (SEM), on the other hand, is a multivariate technique for testing hypothetical models with latent and observed variables. This article shows that fixed-effects…
Cheung, Mike W. -L.
Risk Analysis of Coal Mine Construction Project Based on Structural Equation Model
In the process of coal mine construction, it is significant that how to identify the risk factors and to take measures to prevent the occurrence of safety accidents for the mine investment unit to speed up the construction of the new mines and exploit the coal energy rationally. With the ability of structural equation model that processes the variables and
Yue Zhongwen; Han Pengfei; Zhao Ling
The Trauma Outcome Process Assessment Model: A Structural Equation Model Examination of Adjustment
This investigation sought to operationalize a comprehensive theoretical model, the Trauma Outcome Process Assessment, and test it empirically with structural equation modeling. The Trauma Outcome Process Assessment reflects a robust body of research and incorporates known ecological factors (e.g., family dynamics, social support) to explain…
Borja, Susan E.; Callahan, Jennifer L.
Standards-Based Evaluation and Teacher Career Satisfaction: A Structural Equation Modeling Analysis
Structural equation modeling was used to assess the plausibility of a conceptual model specifying hypothesized linkages among perceptions of characteristics of standards-based evaluation, work environment mediators, and career satisfaction and other outcomes. Four comprehensive high schools located in two neighboring counties in southern California provided the data for this study. The schools' districts had recently developed and implemented evaluation systems
Sharon Conley; Donna E. Muncey; Sukkyung You
Meta-Analytic Structural Equation Modeling: A Two-Stage Approach
To synthesize studies that use structural equation modeling (SEM), researchers usually use Pearson correlations (univariate r), Fisher z scores (univariate z), or generalized least squares (GLS) to combine the correlation matrices. The pooled correlation matrix is then analyzed by the use of SEM. Questionable inferences may occur for these ad hoc…
Cheung, Mike W. L.; Chan, Wai
Evaluating Small Sample Approaches for Model Test Statistics in Structural Equation Modeling.
Structural equation modeling (SEM) attempts to remove the negative influence of measurement error and allows for investigation of relationships at the level of the underlying constructs of interest. SEM has been regarded as a "large sample" technique since its inception. Recent developments in SEM, some of which are currently available in popular…
Nevitt, Jonathan
Evaluating Small Sample Approaches for Model Test Statistics in Structural Equation Modeling
Through Monte Carlo simulation, small sample methods for evaluating overall data-model fit in structural equation modeling were explored. Type I error behavior and power were examined using maximum likelihood (ML), Satorra-Bentler scaled and adjusted (SB; Satorra & Bentler, 1988, 1994), residual-based (Browne, 1984), and asymptotically…
Nevitt, Jonathan; Hancock, Gregory R.
A Structural Equation Model of Burnout and Job Exit among Child Protective Services Workers.
Uses a structural equation model to examine the three elements of the Maslach Burnout Inventory (MBI)--emotional exhaustion, depersonalization, and personal accomplishment--in relation to job exit among child protective services workers over a 15-month period. The model was supported, showing the relevance of all three MBI elements of job exit.…
Drake, Brett; Yadama, Gautam N.
On Insensitivity of the Chi-Square Model Test to Nonlinear Misspecification in Structural Equation Models
In this paper, we show that for some structural equation models (SEM), the classical chi-square goodness-of-fit test is unable to detect the presence of nonlinear terms in the model. As an example, we consider a regression model with latent variables and interactions terms. Not only the model test has zero power against that type of…
Mooijaart, Ab; Satorra, Albert
Differential equations to calculate the ionicity factor of hexagonal structure semiconductors
New mathematical models based on analytical expression and differential equations are established. The work aims to model ionicity factor based on energy gap of hexagonal structure semiconductors using density functional theory (DFT) of full-potential linear augmented plane wave (FP-LAPW) within Engel Vosko-General Gradient Approximation (EV-GGA). Our calculated values are in agreement with experimental and theoretical results.
Arif, Ghassan E.; Al-Douri, Y.; Abdullah, Farah Aini; Khenata, R.
Psychological Separation, Attachment Security, Vocational Self-Concept Crystallization, and Career Indecision: A Structural Equation Analysis.
Structural equation modeling was used to test theoretically based models in which psychological separation and attachment security variables were related to career indecision and those relations were mediated through vocational self-concept crystallization. Results indicated that some components of separation and attachment security did relate to…
Tokar, David M.; Withrow, Jason R.; Hall, Rosalie J.; Moradi, Bonnie
Vocabulary and Grammar Knowledge in Second Language Reading Comprehension: A Structural Equation Modeling Study
Using structural equation modeling analysis, this study examined the contribution of vocabulary and grammatical knowledge to second language reading comprehension among 190 advanced Chinese English as a foreign language learners. Vocabulary knowledge was measured in both breadth (Vocabulary Levels Test) and depth (Word Associates Test);…
Zhang, Dongbo
Reliability of Summed Item Scores Using Structural Equation Modeling: An Alternative to Coefficient Alpha
A method is presented for estimating reliability using structural equation modeling (SEM) that allows for nonlinearity between factors and item scores. Assuming the focus is on consistency of summed item scores, this method for estimating reliability is preferred to those based on linear SEM models and to the most commonly reported estimate of…
Green, Samuel B.; Yang, Yanyun
A Confirmatory Structural Equation Model of Achievement Estimated by Dichotomous Attitudes, Interest, and Conceptual Understanding
Many models in science education have tried to clarify the causal relationships of affective variables on student performance, by presenting theoretical models, exploratory SEM (structural equation models), and confirmatory SEM. Based on the literature, the recent AS-TI-CU model scrutinised the most robust stimuli of conceptual understanding (CU):…
Kim, Minkee; Song, Jinwoong
Residuals and the Residual-Based Statistic for Testing Goodness of Fit of Structural Equation Models
The residuals obtained from fitting a structural equation model are crucial ingredients in obtaining chi-square goodness-of-fit statistics for the model. The authors present a didactic discussion of the residuals, obtaining a geometrical interpretation by recognizing the residuals as the result of oblique projections. This sheds light on the…
Foldnes, Njal; Foss, Tron; Olsson, Ulf Henning
Multilevel Modeling of Two Cyclical Processes: Extending Differential Structural Equation Modeling to Nonlinear Coupled Systems
The authors present a dynamical multilevel model that captures changes over time in the bidirectional, potentially asymmetric influence of 2 cyclical processes. S. M. Boker and J. Graham's (1998) differential structural equation modeling approach was expanded to the case of a nonlinear coupled oscillator that is common in bimanual coordination studies in which participants swing hand-held pendulums but is also
Jonathan Butner; Polemnia G. Amazeen; Genna M. Mulvey
Anti-Transgender Prejudice: A Structural Equation Model of Associated Constructs
This study aimed to identify theoretically relevant key correlates of anti-transgender prejudice. Specifically, structural equation modeling was used to test the unique relations of anti-lesbian, gay, and bisexual (LGB) prejudice; traditional gender role attitudes; need for closure; and social dominance orientation with anti-transgender prejudice.…
Tebbe, Esther N.; Moradi, Bonnie
A unified equation of state of dense matter and neutron star structure
An equation of state (EOS) of neutron star matter, describing both the neutron star crust and the liquid core, is calculated. It is based on the effective nuclear interaction SLy of the Skyrme type, which is particularly suitable for the application to the calculation of the properties of very neutron rich matter (Chabanat et al. 1997, 1998). The structure of
F. Douchin; P. Haensel
Maximum Likelihood Estimation of Nonlinear Structural Equation Models with Ignorable Missing Data
The existing maximum likelihood theory and its computer software in structural equation modeling are established on the basis of linear relationships among latent variables with fully observed data. However, in social and behavioral sciences, nonlinear relationships among the latent variables are important for establishing more meaningful models…
Lee, Sik-Yum; Song, Xin-Yuan; Lee, John C. K.
Bayesian Analysis of Nonlinear Structural Equation Models with Nonignorable Missing Data
A Bayesian approach is developed for analyzing nonlinear structural equation models with nonignorable missing data. The nonignorable missingness mechanism is specified by a logistic regression model. A hybrid algorithm that combines the Gibbs sampler and the Metropolis-Hastings algorithm is used to produce the joint Bayesian estimates of…
Lee, Sik-Yum
Comparison of Approaches to Constructing Confidence Intervals for Mediating Effects Using Structural Equation Models
Mediators are variables that explain the association between an independent variable and a dependent variable. Structural equation modeling (SEM) is widely used to test models with mediating effects. This article illustrates how to construct confidence intervals (CIs) of the mediating effects for a variety of models in SEM. Specifically, mediating…
Cheung, Mike W. L.
Bayesian analysis of multi-group nonlinear structural equation models with application to behavioral finance
Structural equation models (SEMs) have been widely used to determine the relationships among certain observed and latent variables in behavioral finance. The purpose of this paper is to develop a Bayesian approach for analysing multi-group nonlinear SEMs. Using recently developed tools in statistical computing, such as the Gibbs sampler, we propose an efficient method to estimate parameters and select an
Bin Lu; Xin-Yuan Song; Xin-Dan Li
Spiritual Leadership and Organizational Culture: A Study of Structural Equation Modeling
The aim of this study is to test the spiritual leadership behaviors of school principles in a structural equation model. The study is designed to test causality with the assumption that causality exists between the two variables. In this study, spiritual leadership behavior of managers is treated as the independent variable whereas the…
Karadag, Engin
Equivalence and Differences between Structural Equation Modeling and State-Space Modeling Techniques
State-space modeling techniques have been compared to structural equation modeling (SEM) techniques in various contexts but their unique strengths have often been overshadowed by their similarities to SEM. In this article, we provide a comprehensive discussion of these 2 approaches' similarities and differences through analytic comparisons and…
Chow, Sy-Miin; Ho, Moon-ho R.; Hamaker, Ellen L.; Dolan, Conor V.
A ballistic limit equation for hypervelocity impacts on CFRP Al H\\/C satellite structures
Composite sandwich panels consisting of Carbon Fiber Reinforced Plastic facesheets bonded to Aluminum honeycomb cores CFRP Al H C SP are amongst the most commonly used structures for satellites due to their relative low mass and high thermal and mechanical stability To assess the threat of micrometeoroid orbital debris M OD on a satellite mission equations which define the limits
S. Ryan; F. Schäfer; R. Destefanis; M. Lambert
The analysis of structural equation models by means of derivative free nonlinear least squares
It is shown that the PAR Derivative-Free Nonlinear Regression program in BMDP can be used to fit structural equation models,\\u000a producing generalized least squares estimates, standard errors, and goodness-of-fit test statistics. Covariance structure\\u000a models more general than LISREL can be analyzed. The approach is particularly useful for dealing with new non-standard models\\u000a and experimenting with alternate methods of estimation.
Sik-Yum Lee; Robert I. Jennrich
Three-dimensional differential equations dynamic analysis for non-linear structures
A new dynamic model is investigated for the solution of the three-dimensional structural analysis problem of a non-linear\\u000a structure subjected under seismic forces. Such problem is reduced to the solution of a system of ordinary differential equations\\u000a of the second kind and this system is numerically evaluated by using a kind of finite elements and by solving the corresponding\\u000a eigenvalues-eigenvectors
E. G. Ladopoulos
Families of solutions to the generalized Ginzburg-Landau equation and structural transitions between them
Solutions to the generalized Ginzburg-Landau equations for superconductors are obtained for a Ginzburg-Landau parameter {kappa} close to unity. The families of solutions with arbitrary number n of flux quanta in a unit cell are analyzed. It is shown that under certain conditions, a cascade of phase transitions between different structures in a magnetic field appears near T{sub c}. Algebraic equations are derived for determining the boundaries of coexistence of different phases on the (T, H{sub 0}) plane.
Ovchinnikov, Yu. N., E-mail: firstname.lastname@example.com [Max-Planck Institute for Physics of Complex Systems (Germany)
The Dirac equation employing an impulse approximation optical potential based on NN phase shifts has been shown to provide a description of the intermediate energy proton-nucleus spin-dependent elastic scattering data not yet found in the context of a Schroedinger approach. Using analytic methods generalized to the Dirac equation, we trace this success to the nonlinear density contributions which arise as a natural consequence of the Dirac approach. This new understanding resurrects the hope of using intermediate energy protons as a probe of nuclear structure details.
Amado, R.D.; Piekarewicz, J.; Sparrow, D.A.; McNeil, J.A.
Self-assembly of nanocomponents into composite structures: derivation and simulation of Langevin equations.
The kinetics of the self-assembly of nanocomponents into a virus, nanocapsule, or other composite structure is analyzed via a multiscale approach. The objective is to achieve predictability and to preserve key atomic-scale features that underlie the formation and stability of the composite structures. We start with an all-atom description, the Liouville equation, and the order parameters characterizing nanoscale features of the system. An equation of Smoluchowski type for the stochastic dynamics of the order parameters is derived from the Liouville equation via a multiscale perturbation technique. The self-assembly of composite structures from nanocomponents with internal atomic structure is analyzed and growth rates are derived. Applications include the assembly of a viral capsid from capsomers, a ribosome from its major subunits, and composite materials from fibers and nanoparticles. Our approach overcomes errors in other coarse-graining methods, which neglect the influence of the nanoscale configuration on the atomistic fluctuations. We account for the effect of order parameters on the statistics of the atomistic fluctuations, which contribute to the entropic and average forces driving order parameter evolution. This approach enables an efficient algorithm for computer simulation of self-assembly, whereas other methods severely limit the timestep due to the separation of diffusional and complexing characteristic times. Given that our approach does not require recalibration with each new application, it provides a way to estimate assembly rates and thereby facilitate the discovery of self-assembly pathways and kinetic dead-end structures. PMID:19466829
Pankavich, S; Shreif, Z; Miao, Y; Ortoleva, P
Self-assembly of nanocomponents into composite structures: Derivation and simulation of Langevin equations
The kinetics of the self-assembly of nanocomponents into a virus, nanocapsule, or other composite structure is analyzed via a multiscale approach. The objective is to achieve predictability and to preserve key atomic-scale features that underlie the formation and stability of the composite structures. We start with an all-atom description, the Liouville equation, and the order parameters characterizing nanoscale features of the system. An equation of Smoluchowski type for the stochastic dynamics of the order parameters is derived from the Liouville equation via a multiscale perturbation technique. The self-assembly of composite structures from nanocomponents with internal atomic structure is analyzed and growth rates are derived. Applications include the assembly of a viral capsid from capsomers, a ribosome from its major subunits, and composite materials from fibers and nanoparticles. Our approach overcomes errors in other coarse-graining methods, which neglect the influence of the nanoscale configuration on the atomistic fluctuations. We account for the effect of order parameters on the statistics of the atomistic fluctuations, which contribute to the entropic and average forces driving order parameter evolution. This approach enables an efficient algorithm for computer simulation of self-assembly, whereas other methods severely limit the timestep due to the separation of diffusional and complexing characteristic times. Given that our approach does not require recalibration with each new application, it provides a way to estimate assembly rates and thereby facilitate the discovery of self-assembly pathways and kinetic dead-end structures.
Pankavich, S.; Shreif, Z.; Miao, Y.; Ortoleva, P.
The Poisson-Boltzmann equation for biomolecular electrostatics: a tool for structural biology.
Electrostatics plays a fundamental role in virtually all processes involving biomolecules in solution. The Poisson-Boltzmann equation constitutes one of the most fundamental approaches to treat electrostatic effects in solution. The theoretical basis of the Poisson-Boltzmann equation is reviewed and a wide range of applications is presented, including the computation of the electrostatic potential at the solvent-accessible molecular surface, the computation of encounter rates between molecules in solution, the computation of the free energy of association and its salt dependence, the study of pKa shifts and the combination with classical molecular mechanics and dynamics. Theoretical results may be used for rationalizing or predicting experimental results, or for suggesting working hypotheses. An ever-increasing body of successful applications proves that the Poisson-Boltzmann equation is a useful tool for structural biology and complementary to other established experimental and theoretical methodologies. PMID:12501158
Fogolari, F; Brigo, A; Molinari, H
Structure of Thermal Quasi-Fermion in QED/QCD from the Dyson-Schwinger Equation
We non-perturbatively study the structure of quasi-fermion in thermal QED/QCD by solving the Dyson-Schwinger equation in the wide range of temperature as well as of coupling constant. The three-peak structure of the quasi-fermion spectrum, suggested by Harada and Nemoto in a chiral invariant linear sigme model, is clearly seen in QED/QCD. Behavior of the decay width as a function of temperature as well as coupling constant shows the clear deviation from the HTL results. Change of the structure across the boundary of chiral phase transition is also studied in detail. Note from Publisher: This article contains the abstract only.
Nakkagawa, Hisao
Structure-function hierarchies and von Kármán-Howarth relations for turbulence in magnetohydrodynamical equations
We generalize the method of A. M. Polyakov, [Phys. Rev. E 52, 6183 (1995), 10.1103/PhysRevE.52.6183] for obtaining structure-function relations in turbulence in the stochastically forced Burgers equation, to develop structure-function hierarchies for turbulence in three models for magnetohydrodynamics (MHD). These are the Burgers analogs of MHD in one dimension [Eur. Phys. J. B 9, 725 (1999), 10.1007/s100510050817], and in three dimensions (3DMHD and 3D Hall MHD). Our study provides a convenient and unified scheme for the development of structure-function hierarchies for turbulence in a variety of coupled hydrodynamical equations. For turbulence in the three sets of MHD equations mentioned above, we obtain exact relations for third-order structure functions and their derivatives; these expressions are the analogs of the von Kármán-Howarth relations for fluid turbulence. We compare our work with earlier studies of such relations in 3DMHD and 3D Hall MHD.
A Study of the Sampling Variability and "z"-Values of Parameter Estimates from Misspecified Structural Equation Models.
The sampling variability and zeta-values of parameter estimates for misspecified structural equation models were examined. A Monte Carlo study was used. Results are discussed in terms of asymptotic theory and the implications for the practice of structural equation models. (SLD)
Kaplan, David
E Scattering from Irregular Layered Structures Based on Solutions of Generalized Telegraphists' Equations
Upon imposition of the exact boundary conditions at the rough interfaces, Maxwell's equations are transformed into a rigorous set of coupled first-order integro-differential equations for the forward and backward traveling wave amplitudes --generalized telegraphists' equations. In this work only the radiation far fields are considered in detail. Explicit expansions for the scattering coupling coefficients appeared in the generalized telegraphists' equations are derived. A numerical method to solve the generalized telegraphists' equations for the radiation fields is derived for one dimensional rough surfaces. The numerical simulations are carried out for one dimensional deterministic and random rough surfaces. A Monte-Carlo method is applied to carry out numerical simulations for the random rough surfaces. The numerical solutions for the total diffuse scattered fields derived here are in good agreement with the earlier analytical iterative results (Bahar and Rajan, 1979) that accounts for only single scatter, when the maximum surface slope is less than 30 degrees. The generalized field transforms for two dimensional irregular layered structures are also solved here for a three medium scattering problem. Using a first order iterative procedure, the diffuse scattered fields from irregular multilayered structures are shown to be expressed as the sum of the first order diffuse scattered fields from each individual rough interface. For the two dimensional three medium structures with irregular interfaces, the full wave like and cross polarized diffuse scattered fields are derived. The general bistatic Mueller matrix elements are also derived here. They relate the incident to the scattered Stokes vectors. For two dimensionally rough surfaces the vertically and horizontally polarized waves are depolarized upon scattering. The rough surface characteristics is assumed to be homogeneous and isotropic. The surface height, slope, and autocorrelation function are assumed to be Gaussian. The thickness of the coating material is assumed to be uniform. For the numerical simulations only the backscatter case is considered since this analysis is mainly used for remote sensing.
Zhang, Yuzhi
This paper presents a new Bayesian nonlinear structural equation modeling approach to hierarchical model assessment of dynamic systems, considering uncertainty in both predicted and measured time series data. A generalized structural equation modeling with nonlinear latent variables is presented to model two sets of relationships in multivariate hierarchical model assessment, namely, the computational model to system-level data, and low-level data to system-level data. A hierarchical Bayesian network with Markov Chain Monte Carlo simulation and Gibbs sampling is developed to represent the two relationships and estimate the influencing factors between them. A Bayesian interval hypothesis testing-based method is employed to quantify the confidence in the predictive model at various levels. The effect of low-level data on the model assessment at the system level is identified by Bayesian inference and factor analysis. The proposed methodology is implemented for hierarchical model validation of three dynamic system problems.
Jiang, Xiaomo; Mahadevan, Sankaran; Urbina, Angel
Internal-structure dependent coefficients in the post-Newtonian equations of motion
The post-3-Newtonian equation of motion for "point particles" recently derived by Damour, Jaranowski and Schafer and by Blanchet and Faye contains a term whose numerical coefficient has not yet been determined by the methods used to date to derive the equations of motion. One might speculate that the coefficient depends on the internal structure of the bodies, so that, for example, it would have different values for polytropic stellar models with different polytropic indices. We show here that this is not the case -- the coefficient must take the same value for all spherically symmetric bodies -- and that such internal-structure dependent coefficients cannot arise at orders below the 5th post Newtonian order. The argument is based on an earlier, matched asymptotic expansion based analysis of the interaction of the orbital motion and internal degrees of freedom in binary stellar systems.
Flanagan, Eanna
Prediction of Shock Wave Structure in Weakly Ionized Gas Flow by Solving MGD Equation
This paper reports the recent research results of shockwave structure predictions using a new developed code. The modified Rankine-Hugoniot relations across a standing normal shock wave are discussed and adopted to obtain jump conditions. Coupling a electrostatic body force to the Burnett equations, the weakly ionized flow field across the shock wave was solved. Results indicated that the Modified Rankine-Hugoniot equations for shock wave are valid for a wide range of ionization fraction. However, this model breaks down with small free stream Mach number and with large ionization fraction. The jump conditions also depend on the value of free stream pressure, temperature and density. The computed shock wave structure with ionization provides results, which indicated that shock wave strength may be reduced by existence of weakly ionized gas.
Deng, Z. T.; Oviedo-Rojas, Ruben; Chow, Alan; Litchford, Ron J.; Cook, Stephen (Technical Monitor)
Gastrointestinal and Psychological Mediators of Health-Related Quality of Life in IBS and IBD: A Structural Equation Modeling Analysis
Objective Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are chronic gastrointestinal (GI) syndromes in which both GI and psychological symptoms have been shown to negatively impact health-related quality of life (HRQOL). The objective of this study was to use structural equation modeling (SEM) to characterize the interrelationships among HRQOL, GI, and psychological symptoms to improve our understanding of the illness processes in both conditions. Methods Study participants included 564 Rome positive IBS patients and 126 IBD patients diagnosed via endoscopic and / or tissue confirmation. All patients completed questionnaires to assess bowel symptoms, psychological symptoms (SCL-90R), and HRQOL (SF-36). SEM with its two components of confirmatory analyses and structural modeling were applied to determine the relationships between GI and psychological symptoms and HRQOL within the IBS and IBD groups. Results For both IBD and IBS, psychological distress was found to have a stronger direct effect on HRQOL(?0.51 and ?0.48 for IBS and IBD, respectively) than GI symptoms (?0.25 and ?0.28). The impact of GI symptoms on psychological distress was stronger in IBD compared with IBS (0.43 vs. 0.22; P <0.05). The indirect effect of GI symptoms on HRQOL operating through psychological distress was significantly higher in IBD than IBS (?0.21 vs. ?0.11; P <0.05). Conclusions Psychological distress is less dependent on GI symptom severity in IBS compared with IBD even though the degree that psychological distress impacts HRQOL is similar. The findings emphasize the importance of addressing psychological symptoms in both syndromes.
Naliboff, Bruce D.; Kim, Sharon E.; Bolus, Roger; Bernstein, Charles N.; Mayer, Emeran A.; Chang, Lin
Asymptotics, structure, and integration of sound-proof atmospheric flow equations
Relative to the full compressible flow equations, sound-proof models filter acoustic waves while maintaining advection and internal waves. Two well-known sound-proof models, an anelastic model by Bannon and Durran's pseudo-incompressible model, are shown here to be structurally very close to the full compressible flow equations. Essentially, the anelastic model is obtained by suppressing ? t ? in the mass continuity equation and slightly modifying the gravity term, whereas the pseudo-incompressible model results from dropping ? t p from the pressure equation. For length scales small compared to the density and pressure scale heights, the anelastic model reduces to the Boussinesq approximation, while the pseudo-incompressible model approaches the zero Mach number, variable density flow equations. Thus, for small scales, both models are asymptotically consistent with the full compressible flow equations, yet the pseudo-incompressible model is more general in that it remains valid in the presence of large density variations. For the relatively small density variations found in typical atmosphere-ocean flows, both models are found to yield very similar results, with deviations between models much smaller than deviations obtained when using different numerical schemes for the same model. This in agreement with Smolarkiewicz and Dörnbrack (Int J Numer Meth Fluids 56:1513-1519, 2007). Despite these useful properties, neither model can be derived by a low-Mach number asymptotic expansion for length scales comparable to the pressure scale height, i.e., for the regime they were originally designed for. Derivations of these models via scale analysis ignore an asymptotic time scale separation between advection and internal waves. In fact, only the classical Ogura and Phillips model, which assumes weak stratification of the order of the Mach number squared, can be obtained as a leading-order model from systematic low Mach number asymptotic analysis. Issues of formal asymptotics notwithstanding, the close structural similarity of the anelastic and pseudo-incompressible models to the full compressible flow equations makes them useful limit systems in building computational models for atmospheric flows. In the second part of the paper, we propose a second-order finite-volume projection method for the anelastic and pseudo-incompressible models that observes these structural similarities. The method is applied to test problems involving free convection in a neutral atmosphere, the breaking of orographic waves at high altitudes, and the descent of a cold air bubble in the small-scale limit. The scheme is meant to serve as a starting point for the development of a robust compressible atmospheric flow solver in future work.
Klein, Rupert
Dual Spaces Structure of Quantum Kinetic Equations ---Quantum Systems vs Classical Systems---
The relation between the Hilbert space structure and the generalizedspaces structure represented by dual states for dissipative kinetic equation is discussed for quantum systems. As working examples, we consider the systems of a harmonic oscillator or a particle interacting with a thermal reservoir and construct analytic solutions to the eigenvalue problem of the quantum collision operators of these systems. The generalized spaces structure of the eigenfunctions indicates that dissipation destroys the Hilbert space structure of the undamped system. In the Wigner representation where the quantum collision operators closely resemble the classical kinetic operators in phase space, the Hilbert space structure can be restored to certain extent by introducing a weighted norm or a similarity transformation on the operators. However, in the position space where the collision operators have no classical counterpart, generalized spaces description cannot be avoided.
Tay, B. A.; Petrosky, T.
The impact of residential neighborhood type on travel behavior: A structural equations modeling approach
. Using a system of structural equations, this paper empirically examines the relationship of residential neighborhood type\\u000a to travel behavior, incorporating attitudinal, lifestyle, and demographic variables. Data on these variables were collected\\u000a from residents of five neighborhoods in the San Francisco Bay Area in 1993 (final N=515), including "traditional" and "suburban" as well as mixtures of those two extremes. A
Michael N. Bagley; Patricia L. Mokhtarian
An Examination of Statistical Power in Multigroup Dynamic Structural Equation Models
This study used statistical simulation to calculate differential statistical power in dynamic structural equation models with groups (as in McArdle & Prindle, 2008). Patterns of between-group differences were simulated to provide insight into how model parameters influence power approximations. Chi-square and root mean square error of approximation (RMSEA) power approximation procedures were used to compare the effects of parameter manipulations
John J. Prindle; John J. McArdle
Modeling interactions of submersed plant biomass and environmental factors in a stream using structural equation modeling
This study investigated the interactions of submersed plants with environmental factors using structural equation modeling\\u000a (SEM) and evaluated the effect strength of respective factors in an aquatic ecosystem using a data set collected at a fourth\\u000a order stream in Japan. A model that simultaneously examines the relative importance of factors of the system has developed.\\u000a The investigated factors included plant
Nguyen Thanh Hung; Takashi Asaeda; Jagath Manatunge
A general structural equation model with dichotomous, ordered categorical, and continuous latent variable indicators
A structural equation model is proposed with a generalized measurement part, allowing for dichotomous and ordered categorical variables (indicators) in addition to continuous ones. A computationally feasible three-stage estimator is proposed for any combination of observed variable types. This approach provides large-sample chi-square tests of fit and standard errors of estimates for situations not previously covered. Two multiple-indicator modeling examples
A Bayesian structural equations model for multilevel data with missing responses and missing covariates
Motivated by a large multilevel survey conducted by the US Veterans Health Administration\\u000a(VHA), we propose a structural equations model which involves a set of latent variables to\\u000acapture dependence between different responses, a set of facility level random effects to\\u000acapture facility heterogeneity and dependence between individuals within the same\\u000afacility, and a set of covariates to account for
Sonali Das; Ming-Hui Chen; Sungduk Kim; Nicholas Warren
Climate change, theory of planned behavior and values: a structural equation model with mediation analysis
An online survey about climate change was conducted 2008\\/2009 among all university members (N = 3541). Using the Theory of\\u000a Planned Behavior and Cultural Theory within a structural equation modeling approach, one main goal was to explain climate-friendly\\u000a behavioral intentions and the underlying psychological processes comprehensively and to show the interdependencies between\\u000a both approaches. The model explained 72% of the
Aysel Tikir; Bernard Lehmann
Meta-analysis is the statistical analysis of a collection of analysis results from individual studies, conducted for the purpose of integrating the findings. Structural equation modeling (SEM), on the other hand, is a multivariate technique for testing hypothetical models with latent and observed variables. This article shows that fixed-effects meta-analyses with the following characteristics can be modeled in the SEM framework:
Mike W.-L. Cheung
Longitudinal structural equation modeling (SEM) can be a basis for making prescriptive statements on educational practice\\u000a and offers yields over "traditional" statistical techniques under the general linear model. The extent to which prescriptive\\u000a statements can be made will rely on the appropriate accommodation of key elements of research design, measurement, and theory.\\u000a If these key elements are not adequately incorporated
Andrew J. Martin
A ballistic limit equation for hypervelocity impacts on composite honeycomb sandwich panel satellite structures
During a recent experimental test campaign performed in the framework of ESA Contract 16721, the ballistic performance of multiple satellite-representative Carbon Fibre Reinforced Plastic (CFRP)\\/Aluminium honeycomb sandwich panel structural configurations (GOCE, Radarsat-2, Herschel\\/Planck, BeppoSax) was investigated using the two-stage light-gas guns at EMI. The experimental results were used to develop and validate a new empirical Ballistic Limit Equation (BLE), which
S. Ryan; F. Schaefer; R. Destefanis; M. Lambert
Application of the lognormal equation to assess phytoplankton community structural changes induced by marine eutrophication
A methodological approach was developed for the quantification of the structural changes of phytoplankton communities induced\\u000a by marine eutrophication. The lognormal equation assigning species abundance to doubling intervals (octaves) of individuals\\u000a formed the basis of the proposed methodology and the field validation process was based on phytoplankton enumeration and classification\\u000a data characteristic of eutrophic, mesotrophic and oligotrophic waters. Five octave
George Tsirtsis; Sofie Spatharis; Michael Karydis
Background Observational studies in epidemiology always involve concerns regarding validity, especially measurement error, confounding, missing data, and other problems that may affect the study outcomes. Widely used standard statistical techniques, such as multiple regression analysis, may to some extent adjust for these shortcomings. However, structural equations may incorporate most of these considerations, thereby providing overall adjusted estimations of associations. This approach was used in a large epidemiological data set from a prospective study of developmental methyl-mercury toxicity. Results Structural equation models were developed for assessment of the association between biomarkers of prenatal mercury exposure and neuropsychological test scores in 7 year old children. Eleven neurobehavioral outcomes were grouped into motor function and verbally mediated function. Adjustment for local dependence and item bias was necessary for a satisfactory fit of the model, but had little impact on the estimated mercury effects. The mercury effect on the two latent neurobehavioral functions was similar to the strongest effects seen for individual test scores of motor function and verbal skills. Adjustment for contaminant exposure to poly chlorinated biphenyls (PCBs) changed the estimates only marginally, but the mercury effect could be reduced to non-significance by assuming a large measurement error for the PCB biomarker. Conclusions The structural equation analysis allows correction for measurement error in exposure variables, incorporation of multiple outcomes and incomplete cases. This approach therefore deserves to be applied more frequently in the analysis of complex epidemiological data sets.
Budtz-J?rgensen, Esben; Keiding, Niels; Grandjean, Philippe; Weihe, Pal
On the application of structural equation modeling for the construction of a health index
Objective The health of an individual is influenced by many factors. These could include factors that are related to the economy and the environment, as well as social and biological factors. Many studies have been carried out to study the effect of these factors on health, in terms of the individual factors or combined factors. The main purpose of this study was to demonstrate the value of structural equation modeling for the construction of an index to describe the health status of an individual. Methods Structural equation modeling was applied to data obtained from 5035 respondents in a survey conducted in the district of Hulu Langat, Malaysia, in the year 2001 by the Department of Community Health, Medical Faculty, Universiti Kebangsaan Malaysia, Malaysia. The survey involved the gathering of information on the respondents' demography, lifestyles, mental health condition, and biomarkers. Results Socio-demography and mental health condition were found to have a direct effect on the health index. However, lifestyle had an indirect effect on the health index, as mediated by the mental health. Based on the indicator of model fit, the proposed model fits the data well. Conclusions Structural equation modeling was found to be pertinent to be used for analyzing the health index of a particular individual.
Ibrahim, Kamarulzaman; Jemain, Abdul Aziz
How Structure Sense for Algebraic Expressions or Equations Is Related to Structure Sense for Abstract Algebra
Many students have difficulties with basic algebraic concepts at high school and at university. In this paper two levels of algebraic structure sense are defined: for high school algebra and for university algebra. We suggest that high school algebra structure sense components are sub-components of some university algebra structure sense…
Novotna, Jarmila; Hoch, Maureen
Testing mediation using multiple regression and structural equation modeling analyses in secondary data.
Mediation analysis in child and adolescent development research is possible using large secondary data sets. This article provides an overview of two statistical methods commonly used to test mediated effects in secondary analysis: multiple regression and structural equation modeling (SEM). Two empirical studies are presented to illustrate the respective circumstances in which the two methods are most useful. One study examines the mediated effect of parents' social capital on parent involvement in Head Start programs through parent-child bond. The other study assesses the mediating effects of structured routine activities, delinquent association, and prosocial belief on the relationship between religiosity and juvenile delinquency. PMID:21917711
Li, Spencer D
Statistical analysis of nonlinear structural equation models with continuous and polytomous data.
A general nonlinear structural equation model with mixed continuous and polytomous variables is analysed. A Bayesian approach is proposed to estimate simultaneously the thresholds, the structural parameters and the latent variables. To solve the computational difficulties involved in the posterior analysis, a hybrid Markov chain Monte Carlo method that combines the Gibbs sampler and the Metropolis-Hasting algorithm is implemented to produce the Bayesian solution. Statistical inferences, which involve estimation of parameters and their standard errors, residuals and outliers analyses, and goodness-of-fit statistics for testing the posited model, are discussed. The proposed procedure is illustrated by a simulation study and a real example. PMID:11109705
Lee, S Y; Zhu, H T
Improving the correlation structure selection approach for generalized estimating equations and balanced longitudinal data.
Generalized estimating equations are commonly used to analyze correlated data. Choosing an appropriate working correlation structure for the data is important, as the efficiency of generalized estimating equations depends on how closely this structure approximates the true structure. Therefore, most studies have proposed multiple criteria to select the working correlation structure, although some of these criteria have neither been compared nor extensively studied. To ease the correlation selection process, we propose a criterion that utilizes the trace of the empirical covariance matrix. Furthermore, use of the unstructured working correlation can potentially improve estimation precision and therefore should be considered when data arise from a balanced longitudinal study. However, most previous studies have not allowed the unstructured working correlation to be selected as it estimates more nuisance correlation parameters than other structures such as AR-1 or exchangeable. Therefore, we propose appropriate penalties for the selection criteria that can be imposed upon the unstructured working correlation. Via simulation in multiple scenarios and in application to a longitudinal study, we show that the trace of the empirical covariance matrix works very well relative to existing criteria. We further show that allowing criteria to select the unstructured working correlation when utilizing the penalties can substantially improve parameter estimation. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24504841
Westgate, Philip M
Predicting and understanding Korean high school students' science-track choice: Testing the theory of reasoned action by structural equation modeling
The theory of reasoned action (Ajzen & Fishbein, 1980; Fishbein & Ajzen, 1975) was used to predict and understand Korean high school students' track choice for college entrance. First-year high school students (N = 665) from four representative regions of Korea participated in the study. The survey instruments were questionnaires developed according to the guidelines of the TRA. The target behavior of interest in this study was Korean students' choice of the science track when they completed the track application forms during the first year of high school. Predictors included TRA model and external variables. Multiple regression and the structural equation modeling with LISREL (Jöreskog & Sörbom, 1986) were used to analyze the data. The TRA was found to be applicable for understanding and predicting track choice, with minor modifications. Subjective norm was found to exert a direct influence on personal beliefs and the target behavior.
Myeong, Jeon-Ok; Crawley, Frank E.
Basics of Developing Questionnaires
NSDL National Science Digital Library
Whether developing questions for questionnaires or interviews or focus groups, there are certain guidelines that help to ensure that respondents provide information that is useful and can later be analyzed. This resource offers advice on developing questions for interviews or focus groups. It contains basics conducting the interviews, providing directions to respondents as well as guidelines for composing the content and wording of the questionnaire. This resource is aimed for use in workshops/conferences and is intended for novice evaluators.
Mcnamara, Carter
The functional status questionnaire
A comprehensive functional assessment requires thorough and careful inquiry, which is difficult to accomplish in most busy\\u000a clinical practices. This paper examines the reliability and validity of the Functional Status Questionnaire (FSQ), a brief,\\u000a standardized, self-administered questionnaire designed to provide a comprehensive and feasible assessment of physical, psychological,\\u000a social and role function in ambulatory patients. The FSQ can be completed
Alan M. Jette; Allyson R. Davies; Paul D. Cleary; David R. Calkins; Lisa V. Rubenstein; Arlene Fink; Jacqueline Kosecoff; Roy T. Young; Robert H. Brook; Thomas L. Delbanco
Geometric Properties of the Maxwell Set and a Vortex Filament Structure for Burgers Equation
The inviscid limit of the stochastic Burgers equation is discussed in terms of the level surfaces of the minimising Hamilton Jacobi function, the classical mechanical caustic and the Maxwell set and their algebraic pre-images under the classical mechanical flow map. We examine the geometry of the Maxwell set in terms of the behaviour of the pre-Maxwell set, the pre-caustic and the pre-level surfaces. In particular, contrary to the ideas of Helmholtz and Lord Kelvin, we prove that even if initially the fluid flow is irrotational, in the inviscid limit, associated with the advent of the Maxwell set a non-zero vorticity vector forms in the fluid with vortex lines on the Maxwell set. This suggests that in quite general circumstances for small viscosity there is a vortex filament structure near the Maxwell set for both deterministic and stochastic Burgers equations.
Neate, A. D.; Truman, A.
Near-edge structures from first principles all-electron Bethe-Salpeter equation calculations
We obtain x-ray absorption near-edge structures (XANES) by solving the equation of motion for the two-particle Green's function for the electron-hole pair, the Bethe-Salpeter equation (BSE), within the all-electron full-potential linearized augmented plane wave method (FPLAPW). The excited states are calculated for the Li K-edge in the insulating solids LiF, Li2O and Li2S, and absorption spectra are compared with independent particle results using the random phase approximation (RPA), as well as supercell calculations using the core-hole approximation within density functional theory (DFT). The binding energies of strongly bound excitations are determined in the materials, and core-exciton wavefunctions are demonstrated for LiF.
Olovsson, W.; Tanaka, I.; Puschnig, P.; Ambrosch-Draxl, C.
Nonlinear propagation of light in structured media: Generalized unidirectional pulse propagation equations.
Unidirectional pulse propagation equations [UPPE, Phys. Rev. E 70, 036604 (2004)] have provided a theoretical underpinning for computer-aided investigations into dynamics of high-power ultrashort laser pulses and have been successfully utilized for almost a decade. Unfortunately, they are restricted to applications in bulk media or, with additional approximations, to simple waveguide geometries in which only a few guided modes can approximate the propagating waveform. The purpose of this work is to generalize the directional pulse propagation equations to structures characterized by strong refractive index differences and material interfaces. We also outline a numerical solution framework that draws on the combination of the bulk-media UPPE method with single-frequency beam-propagation techniques. PMID:23031052
Andreasen, J; Kolesik, M
High Risk Sexual Behaviors for HIV among the In-School Youth in Swaziland: A Structural Equation Modeling Approach
Background Global efforts in response to the increased prevalence of the human immunodeficiency virus (HIV) are mainly aimed at reducing high risk sexual behaviors among young people. However, knowledge regarding intentions of young people to engage in protective sexual behaviors is still lacking in many countries around the world, especially in Sub-Saharan Africa where prevalence of human immunodeficiency virus is the highest. The objective of this study was to test the theory of planned behavior (TPB) for predicting factors associated with protective sexual behaviors, including sexual abstinence and condom use, among in-school youths aged between 15 and 19 years in Swaziland. Methods This cross-sectional survey was conducted using a anonymous questionnaire. A two-stage stratified and cluster random sampling method was used. Approximately one hundred pupils from each of four schools agreed to participate in the study, providing a total sample size of 403 pupils of which 369 were ultimately included for data analysis. The response rate was 98%. Structural equation modeling was used to analyse hypothesized paths. Results The TPB model used in this study was effective in predicting protective sexual behavior among Swazi in-school youths, as shown by model fit indices. All hypothesized constructs significantly predicted intentions for abstinence and condom use, except perceived abstinence controls. Subjective norms were the strongest predictors of intention for premarital sexual abstinence; however, perceived controls for condom use were the strongest predictors of intention for condom use. Conclusions Our findings support application of the model in predicting determinants of condom use and abstinence intentions among Swazi in-school youths.
Chu, Hsin; Liao, Yuan-Mei; Chen, Chiung-Hua; Ou, Keng-Liang; Chang, Lu-I; Chou, Kuei-Ru
The Validation of the Spatial Hearing Questionnaire
Objectives Subjective questionnaires are informative in understanding the difficulties faced by patients with hearing loss. Our intent was to establish and validate a new questionnaire that encompasses situations emphasizing binaural hearing. The Spatial Hearing Questionnaire is a self-report assessment tool utilizing eight subscales representing questions pertaining to the perception of male, female, and children's voices, music in quiet, source localization, understanding speech in quiet, and understanding speech in noise. Design The Spatial Hearing Questionnaire, composed of 24 items, is scored from 0–100. It was administered to 142 subjects using one or two cochlear implants. Speech perception and localization abilities were measured, and the Speech, Spatial and Other Qualities (SSQ) questionnaire was completed to evaluate validity of the questionnaire. Psychometric tests were done to test the reliability and factor structure of the Spatial Hearing Questionnaire. Results Results showed high internal consistency reliability (Cronbach's ? = 0.98) and good construct validity (correlations between the Spatial Hearing Questionnaire and other test measures, including the SSQ, were significant). A preliminary factor analysis revealed scores loaded on three factors, representing the following conditions: localization, speech in noise and music in quiet, and speech in quiet, explaining 64.9, 13.0, and 5.3% of the variance, respectively. Most of the questionnaire items (12/24) loaded onto the first factor which represents the subscale related to source localization. Mean scores on the Spatial Hearing Questionnaire were higher for subjects with bilateral cochlear implants over subjects with a unilateral cochlear implant, consistent with other research and supporting construct validity. Conclusions The Spatial Hearing Questionnaire is a reliable and valid questionnaire which can be completed independently by most patients in about 10 minutes. It is likely to be a valuable tool for clinicians and researchers to measure spatial hearing abilities.
Tyler, Richard S.; Perreau, Ann E.; Ji, Haihong
Impact of empowerment on professional practice environments and organizational commitment among nurses: a structural equation approach.
A higher turnover rate was identified in Chinese staff nurses and it was highly correlated with lower commitment. Empowering work environments that support professional practice have been positively related to nurse outcomes. This study was to integrate structural empowerment theory with magnet hospital characteristics and provide empirical evidence on the relationships between structural empowerment, professional practice environments and organizational commitment. A cross-sectional design was used to examine the relationships in a sample of 750 full-time nurses employed in five Chinese hospitals in 2011. Structural equation modeling was used to test the proposed hypotheses. The results support the hypothesized model. Professional practice environments partially mediated the relationship between empowerment and organizational commitment. Our findings suggest that higher empowerment facilitates the professional practice environments and commitment of these nurses. PMID:23425379
Yang, Jinhua; Liu, Yanhui; Huang, Chunping; Zhu, Lefeng
Psychosocial Problems Among Truant Youth: A Multi-Group, Exploratory Structural Equation Modeling Analysis
Truant youth represent a critical group needing problem-oriented research and involvement in effective services. The limited number of studies on the psychosocial functioning of truant youths have focused on one or a few problem areas, rather than examining co-morbid problem behaviors. The present study addresses the need to examine the interrelationships of multiple domains of psychosocial functioning, including substance involvement, mental health, and delinquency, among truant youth. Exploratory structural equation modeling on baseline data collected on 219 truant youths identified two major factors reflecting psychosocial functioning, and found the factor structure was similar across major sociodemographic subgroups. Further analyses supported the validity of the factor structure. The research and service delivery implications of the findings are discussed.
Dembo, Richard; Briones-Robinson, Rhissa; Barrett, Kimberly; Winters, Ken C.; Ungaro, Rocio; Karas, Lora; Wareham, Jennifer; Belenko, Steven
The structure of general solutions of the Boltzmann equation in the two-dimensional nonlinear VHP model
It is shown that in the two-dimensional VHP-model the Boltzmann equation for the case of spatially homogeneous, isotropic in velocities distribution functions can always be reduced to a linear second-order differential equation. The general structure of the solution, including the case of slowly decaying distributions nonuniquely determined by initial conditions, is found.
Sadovnikov, B. I.; Inozemtseva, N. G.
B. I. Sadovnikov; N. G. Inozemtseva
Direct and Indirect Effects of Education on Job Satisfaction: A Structural Equation Model for the Spanish Case
Empirical literature has traditionally analyzed the effect of education on job satisfaction with single-equation models that ignore interrelationships between theoretical explanatory variables. Their results are somewhat inconclusive. We propose estimating a structural equation model to obtain both the direct effects and the set of indirect…
Fabra, M. Eugenia; Camison, Cesar
During a recent experimental test campaign performed in the framework of ESA Contract 16721, the ballistic performance of multiple satellite-representative Carbon Fibre Reinforced Plastic (CFRP)/Aluminium honeycomb sandwich panel structural configurations (GOCE, Radarsat-2, Herschel/Planck, BeppoSax) was investigated using the two-stage light-gas guns at EMI. The experimental results were used to develop and validate a new empirical Ballistic Limit Equation (BLE), which was derived from an existing Whipple-shield BLE. This new BLE provided a good level of accuracy in predicting the ballistic performance of stand-alone sandwich panel structures. Additionally, the equation is capable of predicting the ballistic limit of a thin Al plate located at a standoff behind the sandwich panel structure. This thin plate is the representative of internal satellite systems, e.g. an Al electronic box cover, a wall of a metallic vessel, etc. Good agreement was achieved with both the experimental test campaign results and additional test data from the literature for the vast majority of set-ups investigated. For some experiments, the ballistic limit was conservatively predicted, a result attributed to shortcomings in correctly accounting for the presence of high surface density multi-layer insulation on the outer facesheet. Four existing BLEs commonly applied for application with stand-alone sandwich panels were reviewed using the new impact test data. It was found that a number of these common approaches provided non-conservative predictions for sandwich panels with CFRP facesheets.
Ryan, S.; Schaefer, F.; Destefanis, R.; Lambert, M.
Using Instrumental Variable (IV) Tests to Evaluate Model Specification in Latent Variable Structural Equation Models*
Structural Equation Modeling with latent variables (SEM) is a powerful tool for social and behavioral scientists, combining many of the strengths of psychometrics and econometrics into a single framework. The most common estimator for SEM is the full-information maximum likelihood estimator (ML), but there is continuing interest in limited information estimators because of their distributional robustness and their greater resistance to structural specification errors. However, the literature discussing model fit for limited information estimators for latent variable models is sparse compared to that for full information estimators. We address this shortcoming by providing several specification tests based on the 2SLS estimator for latent variable structural equation models developed by Bollen (1996). We explain how these tests can be used to not only identify a misspecified model, but to help diagnose the source of misspecification within a model. We present and discuss results from a Monte Carlo experiment designed to evaluate the finite sample properties of these tests. Our findings suggest that the 2SLS tests successfully identify most misspecified models, even those with modest misspecification, and that they provide researchers with information that can help diagnose the source of misspecification.
Kirby, James B.; Bollen, Kenneth A.
Structural equation models to estimate risk of infection and tolerance to bovine mastitis
Background One method to improve durably animal welfare is to select, as reproducers, animals with the highest ability to resist or tolerate infection. To do so, it is necessary to distinguish direct and indirect mechanisms of resistance and tolerance because selection on these traits is believed to have different epidemiological and evolutionary consequences. Methods We propose structural equation models with latent variables (1) to quantify the latent risk of infection and to identify, among the many potential mediators of infection, the few ones that influence it significantly and (2) to estimate direct and indirect levels of tolerance of animals infected naturally with pathogens. We applied the method to two surveys of bovine mastitis in the Walloon region of Belgium, in which we recorded herd management practices, mastitis frequency, and results of bacteriological analyses of milk samples. Results and discussion Structural equation models suggested that, among more than 35 surveyed herd characteristics, only nine (age, addition of urea in the rations, treatment of subclinical mastitis, presence of dirty liner, cows with hyperkeratotic teats, machine stripping, pre- and post-milking teat disinfection, and housing of milking cows in cubicles) were directly and significantly related to a latent measure of bovine mastitis, and that treatment of subclinical mastitis was involved in the pathway between post-milking teat disinfection and latent mastitis. These models also allowed the separation of direct and indirect effects of bacterial infection on milk productivity. Results suggested that infected cows were tolerant but not resistant to mastitis pathogens. Conclusions We revealed the advantages of structural equation models, compared to classical models, for dissecting measurements of resistance and tolerance to infectious diseases, here bovine mastitis. Using our method, we identified nine major risk factors that were directly associated with an increased risk of mastitis and suggested that cows were tolerant but not resistant to mastitis. Selection should aim at improved resistance to infection by mastitis pathogens, although further investigations are needed due to the limitations of the data used in this study.
Measuring worksite health promotion programs: an application of structural equation modeling with ordinal data.
This paper presents a model for measuring the outcome of Worksite Health Promotion Programs through an application of Structural Equation Modeling with ordinal data. We model the function "being healthy" as a vector comprised of three latent or unobservable variables: Health Status, Lifestyle and Stress. Each variable can be measured only indirectly through a set of manifest or observable ordinal indicators. The objective is to derive and analyze the distributions, and changes in distributions over time, of the latent variables on an individual level. The model is analyzed empirically on data from three large Swedish manufacturing firms. PMID:22815096
Odegaard, Fredrik; Roos, Pontus
Stability analysis of age-structured population equations by pseudospectral differencing methods.
In this paper a numerical scheme to investigate the stability of linear models of age-structured population dynamics is studied. The method is based on the discretization of the infinitesimal generator associated to the semigroup of the solution operator by using pseudospectral differencing techniques, hence following the approach recently proposed in Breda et al. [SIAM J Sci Comput 27(2): 482-495, 2005] for delay differential equations. The method computes the rightmost characteristic roots and it is shown to converge with spectral accuracy behavior. PMID:17171510
Breda, Dimitri; Cusulin, Caterina; Iannelli, Mimmo; Maset, Stefano; Vermiglio, Rossana
The study of the pentagon (fusion) equation leds to the Structure and the\\u000aClassification theorem for finite dimenasional Hopf algebras: there exists a\\u000aone to one correspondence between the set of types of n-dimensional Hopf\\u000aalgebtras and the set of the orbits of the resticted Jordan action $GL_n(k)\\u000a\\\\times M_n(k)\\\\otimes M_n(k) \\\\to M_n(k) \\\\otimes M_nk$ $(u, R) \\\\to (u\\\\otimes u)R
Front Structures in a Real Ginzburg-Landau Equation Coupled to a Mean Field
Localized traveling wave trains or pulses have been observed in various experiments in binary mixture convection. For strongly negative separation ratio, these pulse structures can be described as two interacting fronts of opposite orientation. An analytical study of the front solutions in a real Ginzburg-Landau equation coupled to a mean field is presented here as a first approach to the pulse solution. The additional mean field becomes important when the mass diffusion in the mixture is small as is the case in liquids. Within this framework it can lead to a hysteretic transition between slow and fast fronts when the Rayleigh number is changed.
Herrero, Henar; Riecke, Hermann
Pressure-induced structural phase transition and equation of state of LiTaO3.
Using in situ high-pressure x-ray diffraction and ab initio techniques, a high-pressure structure of LiTaO3 has been determined to be an orthorhombic phase with the space group Pnma. At ambient temperature, the transition pressure from the R3c phase (the ordinary phase at ambient pressure and temperature) to the Pnma phase is about 33.0 GPa and the phase transition is reversible. This phase transition can be reproduced qualitatively by ab initio calculations, but with a lower transition pressure of 19.9 GPa. The equation of state of LiTaO3 is also reported. PMID:23649105
Xiang, Shikai; Liu, Lei; Zhao, Jianzhou; Zhou, Xianming; Jing, Qiuming; Zhang, Yi; Liu, Shenggang; Wang, Zhigang; Bi, Yan; Xu, Ji'an; Geng, Huayun; Dai, Chengda; Cai, Lingcang; Wu, Qiang; Liu, Jing; Wang, Chenju; Zhang, Xiulu
The Structure of Preschoolers' Emotion Knowledge: Model Equivalence and Validity Using a Structural Equation Modeling Approach
Research Findings: A theory-based 2-factor structure of preschoolers' emotion knowledge (i.e., recognition of emotional expression and understanding of emotion-eliciting situations) was tested using confirmatory factor analysis. Compared to 1- and 3-factor models, the 2-factor model showed a better fit to the data. The model was found to be…
Bassett, Hideko Hamada; Denham, Susanne; Mincic, Melissa; Graling, Kelly
Working conditions, self-perceived stress, anxiety, depression and quality of life: A structural equation modelling approach
Background The relationships between working conditions [job demand, job control and social support]; stress, anxiety, and depression; and perceived quality of life factors [physical health, psychological wellbeing, social relationships and environmental conditions] were assessed using a sample of 698 male automotive assembly workers in Malaysia. Methods The validated Malay version of the Job Content Questionnaire (JCQ), Depression Anxiety Stress Scales (DASS) and the World Health Organization Quality of Life-Brief (WHOQOL-BREF) were used. A structural equation modelling (SEM) analysis was applied to test the structural relationships of the model using AMOS version 6.0, with the maximum likelihood ratio as the method of estimation. Results The results of the SEM supported the hypothesized structural model (?2 = 22.801, df = 19, p = 0.246). The final model shows that social support (JCQ) was directly related to all 4 factors of the WHOQOL-BREF and inversely related to depression and stress (DASS). Job demand (JCQ) was directly related to stress (DASS) and inversely related to the environmental conditions (WHOQOL-BREF). Job control (JCQ) was directly related to social relationships (WHOQOL-BREF). Stress (DASS) was directly related to anxiety and depression (DASS) and inversely related to physical health, environment conditions and social relationships (WHOQOL-BREF). Anxiety (DASS) was directly related to depression (DASS) and inversely related to physical health (WHOQOL-BREF). Depression (DASS) was inversely related to the psychological wellbeing (WHOQOL-BREF). Finally, stress, anxiety and depression (DASS) mediate the relationships between job demand and social support (JCQ) to the 4 factors of WHOQOL-BREF. Conclusion These findings suggest that higher social support increases the self-reported quality of life of these workers. Higher job control increases the social relationships, whilst higher job demand increases the self-perceived stress and decreases the self-perceived quality of life related to environmental factors. The mediating role of depression, anxiety and stress on the relationship between working conditions and perceived quality of life in automotive workers should be taken into account in managing stress amongst these workers.
Rusli, Bin Nordin; Edimansyah, Bin Abdin; Naing, Lin
Research on the Governance of Creditor's Rights and Growth of SMEs: An Empirical Analysis Based on Structure Equation Modeling
On the basis of Listed small and medium enterprise's(SMEs) empirical datum in China, this paper applying structure equation model (SEM) to research four dimensions of creditor's rights governance mechanism: solvency, debt financing level, assets maturity structure, debt maturity structure. And we do research on both theory and empirical analysis on the relationship between governance of creditor's rights, enterprise characteristics and
Wang Xiao-ding; Chen Xiao-hong; Zeng Jiang-hong
The Structure of Preschoolers' Emotion Knowledge: Model Equivalence and Validity Using a Structural Equation Modeling Approach
Research Findings: A theory-based 2-factor structure of preschoolers' emotion knowledge (i.e., recognition of emotional expression and understanding of emotion-eliciting situations) was tested using confirmatory factor analysis. Compared to 1- and 3-factor models, the 2-factor model showed a better fit to the data. The model was found to be equivalent for gender, race, age, and socioeconomic risk. Theory and the high
Hideko Hamada Bassett; Susanne Denham; Melissa Mincic; Kelly Graling
The Peer Interaction in Primary School Questionnaire: Testing for Measurement Equivalence and Latent Mean Differences in Bullying between Gender in Egypt, Saudi Arabia and the USA
The Peer Interaction in Primary School Questionnaire (PIPSQ) was developed to assess individuals' levels of bullying and victimization. This study used the approach of latent means analysis (LMA) within the framework of structural equation modeling (SEM) to explore the factor structure and gender differences associated with the PIPSQ in a sample…
Hussein, Mohamed Habashy
Philosophy of Glasser Questionnaire.
As part of the instrumentation to assess the effectiveness of the Schools Without Failure (SWF) program in 10 elementary schools in the New Castle, Pa. School District, the Philosophy of Glasser Questionnaire was developed. This 15-item scale measuring attitudes toward the philosophy of William Glasser had a coefficient alpha reliability of .77…
Masters, James R.; Laverty, Grace E.
The Theory of Questionnaires.
To construct a questionnaire, a set tau of permissible questions is drawn up, i.e. questions which can be realized in practice and each of which makes sense in relationship to set E of events or a certain subset of this set. If under the fixed conditions ...
P. P. Parkhomenko
Diet History Questionnaire
NATIONAL INSTITUTES OF HEALTH Diet History Questionnaire Today's date: MONTH DAY YEAR |___|___| 0 0 1 1 2 2 3 3 4 5 6 7 8 01 Jan 02 Feb 03 Mar 04 Apr 05 May 06 Jun 07 Jul 08 Aug 09 Sep 10 Oct 11 Nov 12
The Gay Identity Questionnaire
This article describes the development of the Gay Identity Questionnaire (GIQ) which was derived from tenets of the Homosexual Identity Formation (HIF) model proposed by Cass in 1979. The GIQ is a brief measure that may be used by clinicians and researchers for identifying gay males in the various stages of homosexual identity formation. The test construction procedures included the
Stephen Brady; Wilma J. Busse
Fitting data to model: structural equation modeling diagnosis using two scatter plots.
This article introduces two simple scatter plots for model diagnosis in structural equation modeling. One plot contrasts a residual-based M-distance of the structural model with the M-distance for the factor score. It contains information on outliers, good leverage observations, bad leverage observations, and normal cases. The other plot contrasts the residual-based M-distance with the quantile of a chi distribution. It allows the researcher to visually identify clusters of potential outliers. The article further studies the effect of the potential outliers on the overall model evaluation when they are removed according to the order of the clusters exhibited in the plot. Suggestions are provided on determining the outlier status of outstanding cases in real data analysis. Recommendations are also made on the choice of robust methods and maximum likelihood following outlier removal. PMID:20853955
Yuan, Ke-Hai; Hayashi, Kentaro
Vector autoregression, structural equation modeling, and their synthesis in neuroimaging data analysis.
Vector autoregression (VAR) and structural equation modeling (SEM) are two popular brain-network modeling tools. VAR, which is a data-driven approach, assumes that connected regions exert time-lagged influences on one another. In contrast, the hypothesis-driven SEM is used to validate an existing connectivity model where connected regions have contemporaneous interactions among them. We present the two models in detail and discuss their applicability to FMRI data, and their interpretational limits. We also propose a unified approach that models both lagged and contemporaneous effects. The unifying model, structural vector autoregression (SVAR), may improve statistical and explanatory power, and avoid some prevalent pitfalls that can occur when VAR and SEM are utilized separately. PMID:21975109
Chen, Gang; Glen, Daniel R; Saad, Ziad S; Paul Hamilton, J; Thomason, Moriah E; Gotlib, Ian H; Cox, Robert W
Vector Autoregression, Structural Equation Modeling, and Their Synthesis in Neuroimaging Data Analysis
Vector autoregression (VAR) and structural equation modeling (SEM) are two popular brain-network modeling tools. VAR, which is a data-driven approach, assumes that connected regions exert time-lagged influences on one another. In contrast, the hypothesis-driven SEM is used to validate an existing connectivity model where connected regions have contemporaneous interactions among them. We present the two models in detail and discuss their applicability to FMRI data, and interpretational limits. We also propose a unified approach that models both lagged and contemporaneous effects. The unifying model, structural vector autoregression (SVAR), may improve statistical and explanatory power, and avoids some prevalent pitfalls that can occur when VAR and SEM are utilized separately.
Chen, Gang; Glen, Daniel R.; Saad, Ziad S.; Hamilton, J. Paul; Thomason, Moriah E.; Gotlib, Ian H.; Cox, Robert W.
Adjoint design sensitivity analysis of reduced atomic systems using generalized Langevin equation for lattice structures
An efficient adjoint design sensitivity analysis method is developed for reduced atomic systems. A reduced atomic system and the adjoint system are constructed in a locally confined region, utilizing generalized Langevin equation (GLE) for periodic lattice structures. Due to the translational symmetry of lattice structures, the size of time history kernel function that accounts for the boundary effects of the reduced atomic systems could be reduced to a single atom's degrees of freedom. For the problems of highly nonlinear design variables, the finite difference method is impractical for its inefficiency and inaccuracy. However, the adjoint method is very efficient regardless of the number of design variables since one additional time integration is required for the adjoint GLE. Through numerical examples, the derived adjoint sensitivity turns out to be accurate and efficient through the comparison with finite difference sensitivity.
Kim, Min-Geun; Jang, Hong-Lae [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)] [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Cho, Seonho, E-mail: email@example.com [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)] [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)
An extended structure-based model based on a stochastic eddy-axis evolution equation
We have proposed and implemented an extension of the structure-based model for weak deformations. It was shown that the extended model will correctly reduce to the form of standard k-e models for the case of equilibrium under weak mean strain. The realizability of the extended model is guaranteed by the method of its construction. The predictions of the proposed model were very good for rotating homogeneous shear flows and for irrotational axisymmetric contraction, but were seriously deficient in the case of plane strain and axisymmetric expansion. We have concluded that the problem behind these difficulties lies in the algebraic constitutive equation relating the Reynolds stresses to the structure parameters rather than in the slow model developed here. In its present form, this equation assumes that under irrotational strain the principal axes of the Reynolds stresses remain locked onto those of the eddy-axis tensor. This is correct in the RDT limit, but inappropriate under weaker mean strains, when the non-linear eddy-eddy interactions tend to misalign the two sets of principal axes and create some non-zero theta and gamma.
Kassinos, S. C.; Reynolds, W. C.
Bidirectional Relationship between Chronic Kidney Disease and Periodontal Disease: Structural Equation Modeling
Periodontal disease is associated with diabetes, heart disease, and chronic kidney disease (CKD), an effect postulated to be due in part to endovascular inflammation. While a bidirectional relationship between CKD and periodontal disease is plausible, it has not been previously reported in the literature. Over 11 200 adults 18 years or older were identified in the Third National Health and Nutrition Examination Survey. Analyses were conducted in two stages. First, multivariable logistic regression models were fitted to test the hypothesis that periodontal disease was independently associated with CKD. Given the potential that the periodontal disease and CKD relationship may be bidirectional, a two-step analytic approach was used that involved 1) tests for mediation, and 2) structural equation models to examine more complex direct and indirect effects of periodontal disease on CKD, and vice versa. In two separate models periodontal disease (ORAdj =1.62 (95% CI: 1.17-2.26) and edentulism (ORAdj = 1.83 (1.31-2.55) and periodontal disease score (ORAdj = 1.01 (1.01-1.02) were associated with CKD, when simultaneously adjusting for 14 other factors. Three of four structural equation models were most plausible suggesting bidirectional relationships. Collectively, these analyses provide for the first time empirical support for a bidirectional relationship between CKD and periodontal disease, and mediation of that relationship by diabetes duration and hypertension.
Fisher, Monica A.; Taylor, George W.; West, Brady T.; McCarthy, Ellen T.
Coaching efficacy and exploratory structural equation modeling: a substantive-methodological synergy.
The purpose of this article was to provide a substantive-methodological synergy of potential importance to future research in sport and exercise psychology. The substantive focus was to improve the measurement of coaching efficacy by developing a revised version of the coaching efficacy scale (CES) for head coaches (N = 557) of youth sport teams (CES II-YST). The methodological focus was exploratory structural equation modeling (ESEM), a methodology that integrates the advantages of exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) within the general structural equation model (SEM). The synergy was a demonstration of how ESEM (as compared with CFA) may be used, guided by content knowledge, to develop (or confirm) a measurement model for the CES II-YST. A single-group ESEM provided evidence for close model-data fit, while a single-group CFA fit significantly worse than the single-group ESEM and provided evidence for only approximate model-data fit. A multiple-group ESEM provided evidence for partial factorial invariance by coach's gender. PMID:22262705
Myers, Nicholas D; Chase, Melissa A; Pierce, Scott W; Martin, Eric
Actinide electronic structure based on the Dirac equation and density functional theory
Density functional theory (DFT) provides a formally predictive basis for predicting the structural properties of actinides. Although available approximations to the exchange/correlation functional provide accurate predictions for many materials, they fail qualitatively and sometimes quantitatively when applied to actinides. Major contributors to this deficiency are an inadequate treatment of confinement physics and an incomplete treatment of relativity in the underlying equations. The development of a functional correctly incorporating confinement physics with a proper treatment of relativity would provide definitive, internally consistent predictions of actinide properties. To enable the development of such a functional and quantify the predictions of currently available functionals, we have developed an efficient first-principles electronic structure method based on the Dirac equation. Results are compared with current methods, and the implications for relativistic density functionals discussed. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
Wills, John M.; Mattsson, Ann E.
Depth Averaged Equations Applied To Study of Defense Structures Effects On Dense Avalanche Flows
Avalanche zoning and protection devices are the complementary tools used to assess avalanche risk and protect persons and human activities in mountainous areas. Despite the intensive use of defense structures as protection against avalanches, their hydraulic and structural effects are not well known. Many structures were designed empirically using expert knowledge or knowledge developed in other domain such as hydraulic. Defence structures effects in terms of energy dissipation, deviation and snow retention are difficult to study in situ. The cost and difficulties of experiments, the danger and the weak annual number of avalanches in a given site, are the reasons why scientists oriented their research towards the use of numerical or laboratory physical models. This paper presents and discuss the possibilities to use depth averaged equations to study dense avalanche flows around defence structures. The used numerical resolu- tion method is based on an upwind numerical scheme. Equations are integrated on each cell of the mesh and the numerical fluxes are calculated thanks to a simplified Riemann solver where the retained solution is obtained as a combination of shock and rarefaction founctions. This allows taking into account the topography variation and jets and surges presence. These two characteristics are needed because both exper- imental and in situ observations showed a significant topography modifications and jets and surges formations during interaction between avalanche flows and structures. The case of vertical surfaces such as those made of concrete destined to deviate flows are treated by appropriated boundary condition functions. A discussion about the best way to integrate defence structures in such model is presented and discussed. This modelisation has, in a first time, been tested on analytical solutions and on experimen- tal laboratory scale model results. These tests have shown the capacity of this model, despite the strong hypothesis, to reproduce correctly some experimentally observed characteristics. In a second phase, this model was applied to study a well documented real case where a large avalanche flow interacted with a complex protection device composed of several types of defence structures. This comparison showed a good con- formity between the numerical results and in-situ observations concerning the global characteristics of the flows such as the deposit and the trajectory of the avalanche.
Naaim, M.; Bouvet-Naaim, F.; Faug, T.; Lachamp, P.
The Questionnaire of Lifestyle Change in Regard to Problematic Internet Use: Factor Structure and Concurrent and Cross-Year Predictive Utilities
This study constructed a questionnaire, named "Lifestyle Change in Regard to Problematic Internet Use (LC-PIU)," for helping school psychologists detect early indications of PIU-related lifestyle changes in university populations. Our focus is on all university students who use the Internet, not users who already show dependent symptoms. The…
Yeh, Yu-Chen; Lin, Sunny S. J.; Tseng, Yin-Hsing; Hwang, Fang-Ming
Therapist Use-of-Self Orientations Questionnaire: A Reliability and Validity Study
This article describes the development of the Therapist Use-of-Self Orientation Questionnaire (TUSO-Q), an instrument designed\\u000a to measure therapists' use-of-self orientations while working with clients. A total of 373 therapists participated in this\\u000a study. Exploratory factor analysis in the structural equation modeling context revealed three different therapist use-of-self\\u000a orientations: Transpersonal, Contextual, and Instrumental. The final model provided an excellent fit to
Stephen A. AndersonJessica; Jessica Sanderson; Iva Košuti?
Modeling and treating internalizing psychopathology in a clinical trial: a latent variable structural equation modeling approach
Background Clinical trials are typically designed to test the effect of a specific treatment on a single diagnostic entity. However, because common internalizing disorders are highly correlated ('co-morbid '), we sought to establish a practical and parsimonious method to characterize and quantify changes in a broad spectrum of internalizing psychopathology targeted for treatment in a clinical trial contrasting two transdiagnostic psychosocial interventions. Method Alcohol dependence treatment patients who had any of several common internalizing disorders were randomized to a six-session cognitive-behavioral therapy (CBT) experimental treatment condition or a progressive muscle relaxation training (PMRT) comparison treatment condition. Internalizing psychopathology was characterized at baseline and 4 months following treatment in terms of the latent structure of six distinct internalizing symptom domain surveys. Results Exploratory structural equation modeling (ESEM) identified a two-factor solution at both baseline and the 4-month follow-up : Distress (measures of depression, trait anxiety and worry) and Fear (measures of panic anxiety, social anxiety and agoraphobia). Although confirmatory factor analysis (CFA) demonstrated measurement invariance between the time-points, structural models showed that the latent means of Fear and Distress decreased substantially from baseline to follow-up for both groups, with a small but statistically significant advantage for the CBT group in terms of Distress (but not Fear) reduction. Conclusions The approach demonstrated in this study provides a practical solution to modeling co-morbidity in a clinical trial and is consistent with converging evidence pointing to the dimensional structure of internalizing psychopathology.
Kushner, M. G.; Krueger, R. F.; Wall, M. M.; Maurer, E. W.; Menk, J. S.; Menary, K. R.
Symmetric Gauss-Seidel multigrid solution of the Euler equations on structured and unstructured grids
The efficient symmetric Gauss-Seidel (SGS) algorithm for solving the Euler equations of inviscid, compressible flow on structured grids, developed in collaboration with Jameson of Stanford University, is extended to unstructured grids. The algorithm uses a nonlinear formulation of an SGS solver, implemented within the framework of multigrid. The earlier form of the algorithm used the natural (lexicographic) ordering of the mesh cells available on structured grids for the SGS sweeps, but a number of features of the method that are believed to contribute to its success can also be implemented for computations on unstructured grids. The present paper reviews, the features of the SGS multigrid solver for structured gr0ids, including its nonlinear implementation, its use of "absolute" Jacobian matrix preconditioning, and its incorporation of multigrid, and then describes the incorporation of these features into an algorithm suitable for computations on unstructured grids. The implementation on unstructured grids is based on the agglomerated multigrid method developed by Sřrensen, which uses an explicit Runge-Kutta smoothing algorithm. Results of computations for steady, transonic flows past two-dimensional airfoils are presented, and the efficiency of the method is evaluated for computations on both structured and unstructured meshes.
Caughey, David A.
Nonlinear equilibrium spherical dust structures I: Basic equations and criterion for the existence of self-organized structures
Basic equations for dust structures are formulated that account for the balance of the forces, plasma fluxes, and grain charges with allowance for nonlinearity in the screening of individual grains and possible violation of quasineutrality due to the interaction of collective fields with plasma fluxes. A theory of non-linear drag forces exerted by plasma fluxes on dust grains is developed for moderate drift flux velocities, higher than the mean ion thermal velocity but much lower than the acoustic speed. It is shown that equilibrium dust structures have finite sizes and negative charges and that they can exist only in a certain range of intensities of external fluxes on their surfaces. When there is no additional volume ionization, the size of the structures is determined by the intensity of the external flux. A study is made of a weakly ionized dusty plasma in which the interaction of its components with neutral gas atoms plays a major role. The ion, electron, and dust density distributions, as well as the distributions of the dust grain charges and plasma fluxes, are calculated self-consistently as functions of the distance from the center of a structure.
Tsytovich, V. N.
Thermodynamic and structural properties of strongly coupled plasma mixtures from the perturbative HNC-equation
Recently, we developed the perturbative hypernetted-chain (PHNC) integral equation which can predict reliable thermodynamic and structural data for a system of particles interacting with either short range or long range (Coulomb) potential. The present work extends this earlier work to mixtures. This is done by employing a reference potential which is designed to satisfy a thermodynamic consistency on the isothermal compressibility as described in the next section. We test the present theory in Sec. III by applying it to plasma mixtures interacing with either an unscreened or a screened Coulomb potential. We made comparisons of results from the present theory with those from the best available theory, i.e., Rosenfeld`s density functional theory (DFT). The DFT was shown to give internal energy with three to five fignre accuracy compared to a wide range of Monte Carlo data. Meanwhile, small deviations of excess internal energy from the so-called ``liner mixing rule`` (LMR) are better predicted by a less sophiscated theory like the hypernetted- chain (HNC) equation. This rule relates thermodynamics of an unscreened mixture to those for individual components in a strongly coupled regime where the potential energy of a constituent particle is much larger than its kinetic energy. We also apply the present theory to a H{sub 2} + H mixture interacting with Morse potentials. For this sytem, comparison of thermodynamic properties and radial distribution functions from the present theory will be made with those from another successful theory of dense fluid, i.e., the HMSA equation of Zerah and Hansen.
Kang, H.S.; Ree, F.H.
Applying Structural Equation Modeling in the Context of the Theory of Reasoned Action: Some Problems and Solutions.
Problems found in the application of structural equation modeling to the theory of reasoned action are explored, and an alternative model specification is proposed that improves the fit of the data while leaving intact the structural part of the model being tested. Problems and the proposed alternative are illustrated. (SLD)
van den Putte, Bas; Hoogstraten, Johan
Self-Efficacy, School Resources, Job Stressors and Burnout among Spanish Primary and Secondary School Teachers: A Structural Equation Approach
This study examines the relationship between school resources, teacher self-efficacy, potential multi-level stressors and teacher burnout using structural equation modelling. The causal structure for primary and secondary school teachers was also examined. The sample was composed of 724 primary and secondary Spanish school teachers. The changes…
Betoret, Fernando Domenech
Psychometric properties and factor structure of the Three-Factor Eating Questionnaire (TFEQ) in obese men and women. Results from the Swedish Obese Subjects (SOS) study
OBJECTIVE: To evaluate the construct validity of the Three-Factor Eating Questionnaire (TFEQ) in obese men and women.SUBJECTS: A total of 4377 middle-aged, obese subjects in the Swedish Obese Subjects (SOS) study.METHODS: The total sample was randomly split into two data subsets and psychometric testing was performed separately in each sample. Multitrait\\/multi-item analysis was conducted to test scaling assumptions and factor
J Karlsson; L-O Persson; L Sjöström; M Sullivan
The measurement of dietary restraint, disinhibition and hunger: an examination of the factor structure of the Three Factor Eating Questionnaire (TFEQ)
OBJECTIVE: To conduct separate factor analyses of the Three Factor Eating Questionnaire (TFEQ-R, TFEQ-D and TFEQ-H) scales and provide initial evidence of the construct validity of the obtained solutions.DESIGN: A cross-sectional survey with a 12 month retest of a subsample of subjects.SUBJECTS: A total of 553 undergraduate university women with a mean age of 25.0 y. The retest sample comprised
MJ Bond; AJ McDowell; JY Wilkinson
a Two-Level Second-Order Finite Difference Scheme for the Single Term Structure Equation
In the paper [6] the classical single factor term structure equation for models that predict non-negative interest rates is numerically studied. For these models the authors proposed a second order accurate three-level finite difference scheme (FDs) using the appropriate boundary conditions at zero. For the same problem we propose a two-level second-order accurate FDs. We also propose an effective algorithm for solving the difference schemes, for which also follows the positivity of the numerical solution. The flexibility of our FDs makes it easy to change the drift and diffusion terms in the model. The numerical experiments confirm the second-order of accuracy of the scheme and the positivity-convexity property.
Chernogorova, T.; Valkov, R.
Beyond Cassie equation: Local structure of heterogeneous surfaces determines the contact angles of microdroplets.
The application of Cassie equation to microscopic droplets is recently under intense debate because the microdroplet dimension is often of the same order of magnitude as the characteristic size of substrate heterogeneities, and the mechanism to describe the contact angle of microdroplets is not clear. By representing real surfaces statistically as an ensemble of patterned surfaces with randomly or regularly distributed heterogeneities (patches), lattice Boltzmann simulations here show that the contact angle of microdroplets has a wide distribution, either continuous or discrete, depending on the patch size. The origin of multiple contact angles observed is ascribed to the contact line pinning effect induced by substrate heterogeneities. We demonstrate that the local feature of substrate structure near the contact line determines the range of contact angles that can be stabilized, while the certain contact angle observed is closely related to the contact line width. PMID:25059292
Zhang, Bo; Wang, Jianjun; Liu, Zhiping; Zhang, Xianren
Structures and Interactions of Soliton in (2+1)-Dimensional Generalized Nizhnik-Novikov-Veselov Equation
A variable separation approach is used to obtain exact solutions of the (2+1)-dimensional generalized Nizhnik-Novikov-Veselov equation. Two of these exact solutions are analyzed to study the interaction between a line soliton and a y-periodic soliton (i.e. the array of the localized structure in the y direction, which propagates in the x direction) and between two dromions. The interactions between a line soliton and a y-periodic soliton are classified into several types according to the phase shifts due to collision. There are two types of singular interactions. One is the resonant interaction that generates one line soliton while the other is the extremely repulsive or long-range interaction where two solitons interchange each other infinitely apart. Some new phenomena of interaction between two dromions are also reported in this paper, and detailed behaviors of interactions are illustrated both analytically and graphically.
Ruan, Hang-Yu
Time dependent Schrödinger equation on arbitrary structured grids: Application to photoionization
A systematic technique for conservatively discretizing the time dependent Schrödinger equation on an arbitrary structured grid is given. Spatial differencing is carried out by finite volumes, and temporal differencing is carried out semi-implicitly. It is shown that the resulting algorithm conserves probability to within a round-off error regardless of the grid geometry. The algorithm is efficient for both serial and parallel computation. The conservative nature of the algorithm, and its phase accuracy, are demonstrated for a bound state, and for a free state in an electromagnetic field. The ionization rate for a hydrogen atom in a strong electromagnetic field is computed, and compared with the rate from tunneling theory. The regime of validity of tunneling theory is clarified.
Gordon, D. F.; Hafizi, B.
Analyzing average and conditional effects with multigroup multilevel structural equation models
Conventionally, multilevel analysis of covariance (ML-ANCOVA) has been the recommended approach for analyzing treatment effects in quasi-experimental multilevel designs with treatment application at the cluster-level. In this paper, we introduce the generalized ML-ANCOVA with linear effect functions that identifies average and conditional treatment effects in the presence of treatment-covariate interactions. We show how the generalized ML-ANCOVA model can be estimated with multigroup multilevel structural equation models that offer considerable advantages compared to traditional ML-ANCOVA. The proposed model takes into account measurement error in the covariates, sampling error in contextual covariates, treatment-covariate interactions, and stochastic predictors. We illustrate the implementation of ML-ANCOVA with an example from educational effectiveness research where we estimate average and conditional effects of early transition to secondary schooling on reading comprehension.
Mayer, Axel; Nagengast, Benjamin; Fletcher, John; Steyer, Rolf
High-pressure structural behavior and equation of state of NaZnF{sub 3}
We report the results of density functional theory ab-initio calculations and monochromatic synchrotron X-ray diffraction study carried out for orthorhombic NaZnF{sub 3} in the pressure range 0-40 GPa. Perovskite-to-postperovskite phase transition was anticipated by first-principles computations and then observed in high-pressure diamond anvil cell synchrotron diffraction experiment between 14 and 22 GPa. Above 25 GPa postperovskite structure (CaIrO{sub 3} type, space group Cmcm) coexists with another phase, yet unidentified. On decompression, pure postperovskite-type structure was found to be stable down to 4 GPa; below this pressure sample contained both perovskite and postperovskite modifications. Fit of experimental P-V data to the third-order Birch-Murnaghan equation of state gave bulk moduli, K{sub P,0} 64.98+-2.67 and 69.88+-3.69 GPa for perovskite and postperovskite modifications, respectively. Both phases demonstrated strong anisotropy of compressibility. For postperovskite NaZnF{sub 3}, the highest compression was observed along the direction perpendicular to the planes of ZnF{sub 6} octahedra arrangement. - Graphical Abstract: Fit of P-V data obtained from high-pressure X-ray diffraction study of perovskite and postperovskite NaZnF{sub 3} to the third-order Birch-Murnaghan equation of state (solid line). Open and closed symbols represent experimental data corresponding to compression and decompression, respectively. Bulk moduli, K{sub 0,P}, of perovskite and postperovskite phases are 64.98+-2.67 and 69.88+-3.69 GPa.
Yakovlev, Sergey, E-mail: email@example.com [Bragg Institute, Australian Nuclear Science and Technology Organisation, 1 PBM, Menai, NSW 2234 (Australia); Avdeev, Maxim [Bragg Institute, Australian Nuclear Science and Technology Organisation, 1 PBM, Menai, NSW 2234 (Australia); Mezouar, Mohamed [ID-27, European Synchrotron Radiation Facility (ESRF), 6 rue Jules Horowitz, PB220, 38043 Grenoble CEDEX (France)
Application of Lie Algebroid Structures to Unification of Einstein and Yang-Mills Field Equations
Yang-Mills field equations describe new forces in the context of Lie groups and principle bundles. It is of interest to know if the new forces and gravitation can be described in the context of algebroids. This work was intended as an attempt to answer last question. The basic idea is to construct Einstein field equation in an algebroid bundle associated to space-time manifold. This equation contains Einstein and Yang-Mills field equations simultaneously. Also this equation yields a new equation that can have interesting experimental results.
Elyasi, N.; Boroojerdian, N.
Attitudes and doping: a structural equation analysis of the relationship between athletes' attitudes, sport orientation and doping behaviour
Background For effective deterrence methods, individual, systemic and situational factors that make an athlete or athlete group more susceptible to doping than others should be fully investigated. Traditional behavioural models assume that the behaviour in question is the ultimate end. However, growing evidence suggests that in doping situations, the doping behaviour is not the end but a means to an end, which is gaining competitive advantage. Therefore, models of doping should include and anti-doping policies should consider attitudes or orientations toward the specific target end, in addition to the attitude toward the 'tool' itself. Objectives The aim of this study was to empirically test doping related dispositions and attitudes of competitive athletes with the view of informing anti-doping policy developments and deterrence methods. To this end, the paper focused on the individual element of the drug availability – athlete's personality – situation triangle. Methods Data were collected by questionnaires containing a battery of psychological tests among competitive US male college athletes (n = 199). Outcome measures included sport orientation (win and goal orientation and competitiveness), doping attitude, beliefs and self-reported past or current use of doping. A structural equation model was developed based on the strength of relationships between these outcome measures. Results Whilst the doping model showed satisfactory fit, the results suggested that athletes' win and goal orientation and competitiveness do not play a statistically significant role in doping behaviour, but win orientation has an effect on doping attitude. The SEM analysis provided empirical evidence that sport orientation and doping behaviour is not directly related. Conclusion The considerable proportion of doping behaviour unexplained by the model suggests that other factors play an influential role in athletes' decisions regarding prohibited methods. Future research, followed by policy development, should incorporate these factors to capture the complexity of the doping phenomenon and to identify points for effective anti-doping interventions. Sport governing bodies and anti-doping organisations need to recognise that using performance enhancements may be more of a rational, outcome optimizing behaviour than deviance and consider offering acceptable alternative performance-enhancing methods to doping.
Developing Written Questionnaires: Determining if Questionnaires Should be Used
This module provides a strategy for determining whether a written questionnaire is an appropriate means of gathering data to meet the goals of an evaluation. The authors define which conditions are suitable for using questionnaires.
Zalles, Daniel R.; Library, Online E.
3D Steady Euler Equation for Description of Nebular Structures Formation
Stereographic projection of Hopf field on the 3-sphere into Euclidean 3-space is used for description of flow of ideal fluid in accordance with Arnold's structural theorem for 3D steady Euler equation. In such case, flow lines are Villarceau circles lying on tori corresponding to the levels of Bernoulli function. Existence of an optimal torus with minimal relative surface free energy is shown. Corresponding inclination of Villarceau circles to accretion plane is ?/4. Beat of oscillations with wave numbers corresponding to structural radii of ``optimal torus'' lying in accretion plane leads to scaling of ``optimal tori'' with factor k = 1+sin(?/4). ``Optimal tori'' are considered as precursors of planetary orbits and ring systems. Scaling factors of Solar system, directly observed multi-planet HR8799 system, planetesimal belts of inner ring of Pictoris system, in three ring system HD113766, in binary ring systems HD141569, HD98800B, Vega precisely correspond to optimal one. The probability distribution of ratios of semi-major axes of neighbor planets in the indirectly observed multiple-exoplanet systems has two maxima. First maximum close to optimal scaling factor, and second one is similar to squared optimal scaling factor. Scaling factors of satellite systems had deviations depending on central body axial tilt and local ratio of semi-major axes of neighbor planets that explained by coincidence of flow lines involved in toroidal flow around protoplanets and proto-Sun.
Salmin, Vladimir
Modeling Alcohol Use Disorder Severity: An Integrative Structural Equation Modeling Approach
Background: Alcohol dependence is a complex psychological disorder whose phenomenology changes as the disorder progresses. Neuroscience has provided a variety of theories and evidence for the development, maintenance, and severity of addiction; however, clinically, it has been difficult to evaluate alcohol use disorder (AUD) severity. Objective: This study seeks to evaluate and validate a data-driven approach to capturing alcohol severity in a community sample. Method: Participants were non-treatment seeking problem drinkers (n?=?283). A structural equation modeling approach was used to (a) verify the latent factor structure of the indices of AUD severity; and (b) test the relationship between the AUD severity factor and measures of alcohol use, affective symptoms, and motivation to change drinking. Results: The model was found to fit well, with all chosen indices of AUD severity loading significantly and positively onto the severity factor. In addition, the paths from the alcohol use, motivation, and affective factors accounted for 68% of the variance in AUD severity. Greater AUD severity was associated with greater alcohol use, increased affective symptoms, and higher motivation to change. Conclusion: Unlike the categorical diagnostic criteria, the AUD severity factor is comprised of multiple quantitative dimensions of impairment observed across the progression of the disorder. The AUD severity factor was validated by testing it in relation to other outcomes such as alcohol use, affective symptoms, and motivation for change. Clinically, this approach to AUD severity can be used to inform treatment planning and ultimately to improve outcomes.
Moallem, Nathasha R.; Courtney, Kelly E.; Bacio, Guadalupe A.; Ray, Lara A.
Structural Equation Modeling Highlights the Potential of Kim-1 as a Biomarker for Chronic Kidney Disease
Background Chronic kidney disease (CKD) is a major public health problem, and despite continued research in the field, there is still a need to identify both biomarkers of risk and progression, as well as potential therapeutic targets. Structural equation modeling (SEM) is a family of statistical techniques that has been utilized in the fields of sociology and psychology for many years; however, its utilization in the biological sciences is relatively novel. SEM's ability to investigate complex relationships in an efficient, single model could be utilized to understand the progression of CKD, as well as to develop a predictive model to assess kidney status in the patient. Methods Fischer 344 rats were fed either an ad libitum diet or a calorically restricted diet, and a time-course study of kidney structure and function was performed. EQS, a SEM software package, was utilized to generate five CKD models of the Fisher 344 rat and identify relationships between measured variables and estimates of kidney damage and kidney function. Results All models identified strong relationships between a biomarker for CKD, kidney injury molecule-1 (Kim-1) and kidney damage, in the Fischer 344 rat CKD model. Models also indicate a strong relationship between age and renal damage and dysfunction. Conclusion SEM can be used to model CKD and could be useful to examine biomarkers in CKD patients.
Gardiner, Lesley; Akintola, Adebayo; Chen, Gang; Catania, Jeffrey M.; Vaidya, Vishal; Burghardt, Robert C.; Bonventre, Joseph V.; Trzeciakowski, Jerome; Parrish, Alan R.
Testing effective connectivity changes with structural equation modeling: what does a bad model tell us?
Structural equation modeling (SEM) is a statistical method that can assess changes in effective connectivity across tasks or between groups. In its initial application to neuroimaging data, anatomical connectivity provided the constraints to decompose interregional covariances to estimate effective connections. There have been concerns expressed, however, with the validity of interpreting effective connections for a model that does not adequately fit the data. We sought to address this concern by creating two population networks with different patterns of effective connectivity, extracting three samples sizes (N = 100, 60, 20), and then assessing whether the ability to detect effective connectivity differences depended on absolute model fit. Four scenarios were assessed: (1) elimination of a region showing no task differences; (2) elimination of connections with no task differences; (3) elimination of connections that carried task differences, but could be expressed through alternative indirect routes; (4) elimination of connections that carried task differences, and could not be expressed through indirect routes. We were able to detect task differences in all four cases, despite poor absolute model fit. In scenario 3, total effects captured the overall task differences even though the direct effect was no longer present. In scenario 4, task differences that were included in the model remained, but the missing effect was not expressed. In conclusion, it seems that when independent information (e.g., anatomical connectivity) is used to define the causal structure in SEM, inferences about task- or group-dependent changes are valid regardless of absolute model fit. PMID:16929548
Protzner, Andrea B; McIntosh, Anthony R
A structural equation model of plant species richness and its application to a coastal wetland
USGS Publications Warehouse
Studies of plant species richness have often emphasized the role of either community biomass (as an indicator of density effects) or abiotic factors. In this article we present a general model that simultaneously examines the relative importance of abiotic and density effects. General and specific models were developed to examine the importance of abiotic conditions, disturbance, and community biomass on plant species richness. Models were evaluated using structural equation modeling based on data from 190 plots across a coastal marsh landscape. The accepted model was found to explain 45% of the observed variation in richness, 75% of biomass, and 65% of light penetration. Model results indicate that abiotic conditions have both direct effects on the species pool and indirect effects on richness mediated through effects on biomass and shading. Effects of disturbance were found to be indirect via biomass. Strong density effects on richness were indicated by the results, and canopy light penetration was found to be a better predictor of richness than was biomass. Overall, it appears that richness in this coastal landscape is controlled in roughly equal proportions by abiotic influences on the species pool and density effects, with disturbance playing a lesser role. The structure of the general model presented should be applicable to a wide variety of herbaceous plant communities.
Grace, J. B.; Pugesek, B. H.
Parallel workflows for data-driven structural equation modeling in functional neuroimaging.
We present a computational framework suitable for a data-driven approach to structural equation modeling (SEM) and describe several workflows for modeling functional magnetic resonance imaging (fMRI) data within this framework. The Computational Neuroscience Applications Research Infrastructure (CNARI) employs a high-level scripting language called Swift, which is capable of spawning hundreds of thousands of simultaneous R processes (R Development Core Team, 2008), consisting of self-contained SEMs, on a high performance computing system (HPC). These self-contained R processing jobs are data objects generated by OpenMx, a plug-in for R, which can generate a single model object containing the matrices and algebraic information necessary to estimate parameters of the model. With such an infrastructure in place a structural modeler may begin to investigate exhaustive searches of the model space. Specific applications of the infrastructure, statistics related to model fit, and limitations are discussed in relation to exhaustive SEM. In particular, we discuss how workflow management techniques can help to solve large computational problems in neuroimaging. PMID:19876406
Kenny, Sarah; Andric, Michael; Boker, Steven M; Neale, Michael C; Wilde, Michael; Small, Steven L
Bayesian mixture structural equation modelling in multiple-trait QTL mapping.
Quantitative trait loci (QTLs) mapping often results in data on a number of traits that have well-established causal relationships. Many multi-trait QTL mapping methods that account for correlation among the multiple traits have been developed to improve the statistical power and the precision of QTL parameter estimation. However, none of these methods are capable of incorporating the causal structure among the traits. Consequently, genetic functions of the QTL may not be fully understood. In this paper, we developed a Bayesian multiple QTL mapping method for causally related traits using a mixture structural equation model (SEM), which allows researchers to decompose QTL effects into direct, indirect and total effects. Parameters are estimated based on their marginal posterior distribution. The posterior distributions of parameters are estimated using Markov Chain Monte Carlo methods such as the Gibbs sampler and the Metropolis-Hasting algorithm. The number of QTLs affecting traits is determined by the Bayes factor. The performance of the proposed method is evaluated by simulation study and applied to data from a wheat experiment. Compared with single trait Bayesian analysis, our proposed method not only improved the statistical power of QTL detection, accuracy and precision of parameter estimates but also provided important insight into how genes regulate traits directly and indirectly by fitting a more biologically sensible model. PMID:20667167
Mi, Xiaojuan; Eskridge, Kent; Wang, Dong; Baenziger, P Stephen; Campbell, B Todd; Gill, Kulvinder S; Dweikat, Ismail
The Construct Validity of the Illness Cognition Questionnaire: The Robustness of the Three-factor Structure Across Patients with Chronic Pain and Chronic Fatigue
Background The Illness Cognition Questionnaire (ICQ; Evers et al., J Consult Clin Psychol, 69:1026-1036, 2001) assesses three ways of\\u000a cognitively evaluating the stressful and aversive character of a chronic illness: helplessness, acceptance, and perceived\\u000a benefits.\\u000a \\u000a \\u000a \\u000a \\u000a Purpose The purpose of this study was to evaluate the construct validity of the ICQ in individuals with chronic pain and patients\\u000a with chronic fatigue.\\u000a \\u000a \\u000a \\u000a \\u000a Method The ICQ
Emelien Lauwerier; Geert Crombez; Stefaan Van Damme; Liesbet Goubert; Dirk Vogelaers; Andrea W. M. Evers
Solving the Helmholtz equation in conformal mapped ARROW structures using homotopy perturbation method.
The scalar wave equation, or Helmholtz equation, describes within a certain approximation the electromagnetic field distribution in a given system. In this paper we show how to solve the Helmholtz equation in complex geometries using conformal mapping and the homotopy perturbation method. The solution of the mapped Helmholtz equation is found by solving an infinite series of Poisson equations using two dimensional Fourier series. The solution is entirely based on analytical expressions and is not mesh dependent. The analytical results are compared to a numerical (finite element method) solution. PMID:21368995
Reck, Kasper; Thomsen, Erik V; Hansen, Ole
Factor Structure of the Primary Scales of the Inventory of Personality Organization in a Nonclinical Sample Using Exploratory Structural Equation Modeling
Using exploratory structural equation modeling and multiple regression, we examined the factor structure and criterion relations of the primary scales of the Inventory of Personality Organization (IPO; Kernberg & Clarkin, 1995) in a nonclinical sample. Participants (N = 1,260) completed the IPO and measures of self-concept clarity, defenses,…
Ellison, William D.; Levy, Kenneth N.
Using exploratory structural equation modeling and multiple regression, we examined the factor structure and criterion relations of the primary scales of the Inventory of Personality Organization (IPO; Kernberg & Clarkin, 1995) in a nonclinical sample. Participants (N = 1,260) completed the IPO and measures of self-concept clarity, defenses, affect and emotion regulation, and risky and self-injurious behavior. In contrast to
William D. Ellison; Kenneth N. Levy
Hints for Designing Effective Questionnaires
The purpose of this article is to offer tips in designing quality questionnaires and on avoiding common errors. Some of the more prevalent problems in questionnaire development are identified and suggestions of ways to avoid them are offered.
Frary, Robert
Diet History Questionnaire: International Applications
ARP staff adapted the Diet History Questionnaire (DHQ) for use by Canadian populations in collaboration with the Alberta Cancer Board. This questionnaire takes into account the different food fortification polices of the US and Canada.
Guides & Reports for Questionnaire Design
Applied Research Program (ARP) staff use a variety of methods to develop and test questionnaires, including established Questionnaire Design Principles, empirical methods such as Cognitive Testing and psychometric methods such as Item Response Theory Modeling.
ATBC Study - Questionnaires and Forms
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Software Acquisition Process Maturity Questionnaire.
This package contains a copy of the software acquisition process maturity questionnaire. It is intended for those interested in performing and learning about software acquisition process appraisals. This questionnaire is not an appraisal method itself; ra...
J. Ferguson J. Cooper M. Falat M. Fisher A. Guido
Prevalence of chronic pain among Libyan adults in Derna City: a pilot study to assess the reliability, linguistic validity, and feasibility of using an Arabic version of the structured telephone interviews questionnaire on chronic pain.
There are few studies estimating the prevalence of chronic pain in countries from the Middle East. We translated the Structured Telephone Interviews Questionnaire on Chronic Pain from English into Arabic and assessed its reliability and linguistic validity before using it in a telephone survey in Libya to gather preliminary prevalence data for chronic pain. Intraclass correlations for scaled items were high, and there were no differences in answers to nominal items between the first and second completions of the questionnaire. One hundred and 4 individuals participated in a telephone survey. The prevalence of chronic pain was 25.0% (95% CI, 16.7% to 33.3%) and 50.0% (95% CI: 30.8% to 69.2) of the participants with chronic pain scored ? 12 on the Arabic S-LANSS. Mean ± SD duration of pain was 2.8 ± 1.2 years, and pain was more frequent in women (P = 0.02). 53.8% of participants had taken prescription medication for their pain, and 76.9% had used nondrug methods of treatment including traditional Libyan methods such as Kamara, a local herbal concoction. Eighty percent believed that their doctor would rather treat their illness than their pain, and 35% reported that their doctor did not think that their pain was a problem. Some participants complained that the questionnaire was too long with a mean ± SD call duration of 20 ± 5.4 minutes. We conclude that the Arabic Structured Telephone Interviews Questionnaire on Chronic Pain was reliable and linguistically valid and could be used in a large-scale telephone survey on the Libyan population. Our preliminary estimate of prevalence should be considered with caution because of the small sample size. PMID:22978448
Elzahaf, Raga A; Tashani, Osama A; Johnson, Mark I
Survey and Questionnaire Tutorial
What are the important factors to consider when designing a survey? Would it be best conducted via telephone? Or would it be better to have a face-to-face meeting? These are but a few of the topics covered on this site created as a public service by the StatPac group. Visitors can elect to download the entire report on survey design here, or they can just click through the topics that interest them. Each topic includes a brief discussion of its relative importance, and the areas covered include questionnaire length, time considerations, question wording, and sampling methods. It's a thoughtful and helpful resource overall, and it's one that might be put to good use in an introductory statistics course in college.
Structure borne noise analysis using Helmholtz equation least squares based forced vibro acoustic components
This dissertation presents a structure-borne noise analysis technology that is focused on providing a cost-effective noise reduction strategy. Structure-borne sound is generated or transmitted through structural vibration; however, only a small portion of the vibration can effectively produce sound and radiate it to the far-field. Therefore, cost-effective noise reduction is reliant on identifying and suppressing the critical vibration components that are directly responsible for an undesired sound. However, current technologies cannot successfully identify these critical vibration components from the point of view of direct contribution to sound radiation and hence cannot guarantee the best cost-effective noise reduction. The technology developed here provides a strategy towards identifying the critical vibration components and methodically suppressing them to achieve a cost-effective noise reduction. The core of this technology is Helmholtz equation least squares (HELS) based nearfield acoustic holography method. In this study, the HELS formulations derived in spherical co-ordinates using spherical wave expansion functions utilize the input data of acoustic pressures measured in the nearfield of a vibrating object to reconstruct the vibro-acoustic responses on the source surface and acoustic quantities in the far field. Using these formulations, three steps were taken to achieve the goal. First, hybrid regularization techniques were developed to improve the reconstruction accuracy of normal surface velocity of the original HELS method. Second, correlations between the surface vibro-acoustic responses and acoustic radiation were factorized using singular value decomposition to obtain orthogonal basis known here as the forced vibro-acoustic components (F-VACs). The F-VACs enables one to identify the critical vibration components for sound radiation in a similar manner that modal decomposition identifies the critical natural modes in a structural vibration. Finally, the dominant F-VAC responsible for acoustic radiation are decomposed into the natural modes of a vibrating structure, and the critical vibration modes responsible for the dominant F-VAC are identified. Experimental validation for this technology was conducted using a baffled square plate and a scaled model vehicle cabin subject to a point force excitation inside a fully anechoic chamber.
Natarajan, Logesh Kumar
Wing-Body Aeroelasticity Using Finite-Difference Fluid/Finite-Element Structural Equations on Parallel Computers
This paper presents a procedure for computing the aeroelasticity of wing-body configurations on multiple-instruction, multiple-data (MIMD) parallel computers. In this procedure, fluids are modeled using Euler equations discretized by a finite difference method, and structures are modeled using finite element equations. The procedure is designed in such a way that each discipline can be developed and maintained independently by using a domain decomposition approach. A parallel integration scheme is used to compute aeroelastic responses by solving the coupled fluid and structural equations concurrently while keeping modularity of each discipline. The present procedure is validated by computing the aeroelastic response of a wing and comparing with experiment. Aeroelastic computations are illustrated for a High Speed Civil Transport type wing-body configuration.
Byun, Chansup; Guruswamy, Guru P.
Reconstruction of vibroacoustic responses of a highly nonspherical structure using Helmholtz equation least-squares method.
The vibroacoustic responses of a highly nonspherical vibrating object are reconstructed using Helmholtz equation least-squares (HELS) method. The objectives of this study are to examine the accuracy of reconstruction and the impacts of various parameters involved in reconstruction using HELS. The test object is a simply supported and baffled thin plate. The reason for selecting this object is that it represents a class of structures that cannot be exactly described by the spherical Hankel functions and spherical harmonics, which are taken as the basis functions in the HELS formulation, yet the analytic solutions to vibroacoustic responses of a baffled plate are readily available so the accuracy of reconstruction can be checked accurately. The input field acoustic pressures for reconstruction are generated by the Rayleigh integral. The reconstructed normal surface velocities are validated against the benchmark values, and the out-of-plane vibration patterns at several natural frequencies are compared with the natural modes of a simply supported plate. The impacts of various parameters such as number of measurement points, measurement distance, location of the origin of the coordinate system, microphone spacing, and ratio of measurement aperture size to the area of source surface of reconstruction on the resultant accuracy of reconstruction are examined. PMID:19275312
Lu, Huancai; Wu, Sean F
Bayesian model comparison of nonlinear structural equation models with missing continuous and ordinal categorical data.
Missing data are very common in behavioural and psychological research. In this paper, we develop a Bayesian approach in the context of a general nonlinear structural equation model with missing continuous and ordinal categorical data. In the development, the missing data are treated as latent quantities, and provision for the incompleteness of the data is made by a hybrid algorithm that combines the Gibbs sampler and the Metropolis-Hastings algorithm. We show by means of a simulation study that the Bayesian estimates are accurate. A Bayesian model comparison procedure based on the Bayes factor and path sampling is proposed. The required observations from the posterior distribution for computing the Bayes factor are simulated by the hybrid algorithm in Bayesian estimation. Our simulation results indicate that the correct model is selected more frequently when the incomplete records are used in the analysis than when they are ignored. The methodology is further illustrated with a real data set from a study concerned with an AIDS preventative intervention for Filipina sex workers. PMID:15171804
Relationships between dimensions of disability experienced by adults living with HIV: a structural equation model analysis.
As individuals age with HIV it is increasingly important to consider the health-related consequences of HIV and multiple morbidities, known as disability. We assessed relationships between four dimensions of disability among adults living with HIV. We conducted a structural equation modeling analysis using data from 913 participants in the Ontario HIV Treatment Network Cohort Study to determine relationships between four latent variables of disability in the Episodic Disability Framework: physical symptoms and impairments, mental health symptoms and impairments, difficulties with day-to-day activities, and challenges to social inclusion. Results indicated that physical symptoms and impairments, mental health symptoms and impairments and difficulties with day-to-day activities directly or indirectly predicted challenges to social inclusion for adults living with HIV. Challenges to social inclusion were directly predicted by mental health symptoms and indirectly by physical health symptoms via (mediated by) having difficulties carrying out day-to-day activities and mental health symptoms and impairments. These findings provide a basis for conceptualizing disability experienced by people living with HIV. PMID:23132208
O'Brien, Kelly K; Davis, Aileen M; Gardner, Sandra; Bayoumi, Ahmed M; Rueda, Sergio; Hart, Trevor A; Cooper, Curtis; Solomon, Patricia; Rourke, Sean B; Hanna, Steven
A structural equation modeling approach to fatigue-related risk factors for occupational injury.
Occupational injury is associated with numerous individual and work-related risk factors, including long working hours and short sleep duration; however, the complex mechanisms causing such injuries are not yet fully understood. The authors used structural equation modeling (SEM) as a novel approach to examine fatigue-related direct and indirect potential risk factors for occupational injury. The study sample contained 89,366 employed workers from the National Health Interview Survey (pooled across 6 years, 2004-2009), an annual survey of a representative cross-sectional sample of the US population. Direct and indirect effects of weekly hours worked and usual sleep duration on occupational injuries were modeled using SEM procedures for dichotomous outcomes and a complex sampling design. Confounding and mediating effects of gender, age, race/ethnicity, occupation, industry, type of pay, body mass index (BMI), and psychological distress were simultaneously examined. Long working hours and short sleep duration independently increased the risk of injury. Additional direct risk factors were gender, occupation, type of pay, and BMI. At the same time, sleep duration mediated the adverse relations of long working hours, high psychological distress, and high BMI with injury. These findings indicate that SEM is a useful approach with which to examine dichotomous outcomes and indirect effects in complex samples, and it offers a comprehensive new model of injury prediction. PMID:22956514
Arlinghaus, Anna; Lombardi, David A; Willetts, Joanna L; Folkard, Simon; Christiani, David C
Fatigue and physical disability in patients with multiple sclerosis: a structural equation modeling approach.
Although fatigue is one of the most common and disabling symptoms in patients with multiple sclerosis (MS), its pathogenesis is still poorly understood and it is difficult to treat. The aim of the current study was to test the assumptions of a cognitive-behavioral model that explains fatigue and physical disability in MS patients, by comparing this approach with a more traditional biomedical approach. Structural equation modeling was applied to a sample of 262 MS patients. Neither the cognitive-behavioral, nor the biomedical model showed an adequate fit of our data. The modification indices supported an integration of both models, which showed a better fit than those of the separate models. This final model, is notable for at least three features: (1) fatigue is associated with depression and physical disability, (2) physical disability is associated with disease severity and fatigue-related fear and avoidance behavior, and (3) catastrophic interpretations about fatigue, fueled by depression, mediated the relationship between fatigue and fatigue-related fear and avoidance behavior. Our results suggest that an integrated approach, including the modification of catastrophic thoughts about fatigue, would be beneficial in the treatment of fatigue in MS patients. PMID:20508981
Bol, Yvonne; Duits, Annelien A; Lousberg, Richel; Hupperts, Raymond M M; Lacroix, Michelle H P; Verhey, Frans R J; Vlaeyen, Johan W S
Psychological contract breach and outcomes: Combining meta-analysis and structural equation models.
In this study, meta-analytic procedures were used to examine the relationships between psychological contract perceived breach and certain outcome variables, such as organizational commitment, job satisfaction and organizational citizenship behaviours (OCB). Our review of the literature generated 41 independent samples in which perceived breach was used as a predictor of these personal and organizational outcomes. A medium effect size (ES) for desirable outcomes (job satisfaction, organizational commitment, organizational trust, OCB and performance) was obtained (r=-.35). For undesirable outcomes (neglect in role duties and intention to leave), ES were also medium (r=.31). When comparing attitudinal (job satisfaction, organizational commitment, organizational trust) and behavioural outcomes (OCB, neglect in role duties and performance), a stronger ES was found for attitudinal (r=-.24) than for behavioural outcomes (r=-.11). Potential moderator variables were examined, and it was found that they explained only a percentage of variability of primary studies. Structural equation analysis of the pooled meta-analytical correlation matrix indicated that the relationships of perceived breach with satisfaction, OCB, intention to leave and performance are fully mediated by organizational trust and commitment. Results are discussed in order to suggest theoretical and empirical implications. PMID:18674448
Topa Cantisano, Gabriela; Morales Domínguez, J Francisco; Depolo, Marco
An equation of state (EOS) of neutron star matter, describing both the neutron star crust and the liquid core, is calculated. It is based on the effective nuclear interaction SLy of the Skyrme type, which is particularly suitable for the application to the calculation of the properties of very neutron rich matter (Chabanat et al. 1997, 1998). The structure of the crust, and its EOS, is calculated in the T=0 approximation, and under the assumption of the ground state composition. The crust-core transition is a very weakly first-order phase transition, with relative density jump of about one percent. The EOS of the liquid core is calculated assuming (minimal) npemu composition. Parameters of static neutron stars are calculated and compared with existing observational data on neutron stars. The minimum and maximum masses of static neutron stars are 0.094 Msun and 2.05 Msun, respectively. Effects of rotation on the minimum and the maximum mass of neutron stars are briefly discussed.
Douchin, F.; Haensel, P.
The general image quality equation and the structure of the modulation transfer function
Previous work by Hindsley and Mozurkewich (2001) showed that analysis of the Modulation Transfer Function (MTF) demonstrated the proportionality of signal-to-noise in a sparse aperture to the fill factor of the aperture. Analysis of the MTR also could enumerate the noise amplification characteristics of particular sparse apertures. However, such image quality metrics as the General Image Quality Equation (GIQE) also include edge effects, basically due to ringing and reduction in the edge sharpness. Here we report on our analysis of the MTF in order to quantify the relationship between the other terms in the GIQE and the structure of the MTF. We find that, for a fixed amount of optical surface, the image quality will improve with decreasing fill fraction due to an increase in resolution. Apodization of the Wiener Filter used to restore the image, as advocated by Hindsley and Mozurkewich, does not result in an improved image quality; use of the traditional unapodized Wiener Filter is highly favored. While the GIQE does not appear very sensitive to input signal-to-noise ratio (SNR), the input SNR does limit the ability to successfully reconstruct the image and is the ultimate limiting constraint on the fill fraction.
Hindsley, Robert B.; Rickard, Lee J.
Modeling dependent effect sizes with three-level meta-analyses: A structural equation modeling approach.
Meta-analysis is an indispensable tool used to synthesize research findings in the social, educational, medical, management, and behavioral sciences. Most meta-analytic models assume independence among effect sizes. However, effect sizes can be dependent for various reasons. For example, studies might report multiple effect sizes on the same construct, and effect sizes reported by participants from the same cultural group are likely to be more similar than those reported by other cultural groups. This article reviews the problems and common methods to handle dependent effect sizes. The objective of this article is to demonstrate how 3-level meta-analyses can be used to model dependent effect sizes. The advantages of the structural equation modeling approach over the multilevel approach with regard to conducting a 3-level meta-analysis are discussed. This article also seeks to extend the key concepts of Q statistics, I2, and R2 from 2-level meta-analyses to 3-level meta-analyses. The proposed procedures are implemented using the open source metaSEM package for the R statistical environment. Two real data sets are used to illustrate these procedures. New research directions related to 3-level meta-analyses are discussed. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:23834422
Determinants of primary care physicians' referral pattern: a structural equation model approach.
This study examines patient referrals by primary care physicians (PCP) with nurse practitioners and physician assistants (NP-PA) in their medical practices as compared to practices without them. The study uses data from the Robert Wood Johnson Foundation community tracking study (CTS) Physician Survey, Round I (1996-97) and II (1998-99). Structural equations with binary dependent variables were used to examine the links among managed care, the use of NP-PA, the complexity of patient's conditions, and the number of referrals. PCP's with NP-PA were found to have a greater likelihood of treating patients with complex conditions instead of referring them to specialists. Managed care related variables (i.e., large group practice/HMO, the percentage of patients for whom PCPs acted as gatekeepers, and the percentage of managed care revenue from capitated/prepaid contracts) affected PCP' patient referrals, but only through the increased use of NP-PA. PCP's with NP-PA were also found to provide appropriate care to the complex patients. These findings indicate that NP-PA enable PCP to concentrate on patients with more complex conditions thus reducing the number of referrals. In addition, NP-PA is found to affect the gatekeeper role of PCPs. PMID:20351790
Chung, Kyusuk; Yang, Duckhye; Lee, Jun Hyup
Investigating perturbed pathway modules from gene expression data via structural equation models
Background It is currently accepted that the perturbation of complex intracellular networks, rather than the dysregulation of a single gene, is the basis for phenotypical diversity. High-throughput gene expression data allow to investigate changes in gene expression profiles among different conditions. Recently, many efforts have been made to individuate which biological pathways are perturbed, given a list of differentially expressed genes (DEGs). In order to understand these mechanisms, it is necessary to unveil the variation of genes in relation to each other, considering the different phenotypes. In this paper, we illustrate a pipeline, based on Structural Equation Modeling (SEM) that allowed to investigate pathway modules, considering not only deregulated genes but also the connections between the perturbed ones. Results The procedure was tested on microarray experiments relative to two neurological diseases: frontotemporal lobar degeneration with ubiquitinated inclusions (FTLD-U) and multiple sclerosis (MS). Starting from DEGs and dysregulated biological pathways, a model for each pathway was generated using databases information biological databases, in order to design how DEGs were connected in a causal structure. Successively, SEM analysis proved if pathways differ globally, between groups, and for specific path relationships. The results confirmed the importance of certain genes in the analyzed diseases, and unveiled which connections are modified among them. Conclusions We propose a framework to perform differential gene expression analysis on microarray data based on SEM, which is able to: 1) find relevant genes and perturbed biological pathways, investigating putative sub-pathway models based on the concept of disease module; 2) test and improve the generated models; 3) detect a differential expression level of one gene, and differential connection between two genes. This could shed light, not only on the mechanisms affecting variations in gene expression, but also on the causes of gene-gene relationship modifications in diseased phenotypes.
Personality, Self-Estimated Intelligence, and Uses of Music: A Spanish Replication and Extension Using Structural Equation Modeling
This study replicates and extends a recent study on personality, intelligence and uses of music [Chamorro-Premuzic, T., & Furnham, A. (2007). Personality and music: Can traits explain how people use music in everyday life? British Journal of Psychology, 98, 175–185] using Spanish participants and structural equation modeling. Data from 245 university students showed that, in line with our hypotheses, individuals
Tomas Chamorro-Premuzic; Montserrat Gomŕ-i-Freixanet; Adrian Furnham; Anna Muro
Nonlinear Structural Equation Models with the Theory of Planned Behavior: Comparison of Multiple Group and Latent Product Term Analyses
Nonlinear relationships in structural equation analysis became moreinteresting for applied researchers since the implementation of nonlinearconstraints in software programs (i.e., LISREL). This article provides acomprehensive application of the expectancy × value part of the Theory of Planned Behavior (Ajzen, 1991) including interactions of latent variables.The main purpose of the study is to overcome limitations of similarprevious analyses of Baumgartner and
Jost Reinecke
Perceived Social Relationships and Science Learning Outcomes for Taiwanese Eighth Graders: Structural Equation Modeling with a Complex Sampling Consideration
Based on the Trends in International Mathematics and Science Study 2007 study and a follow-up national survey, data for 3,901 Taiwanese grade 8 students were analyzed using structural equation modeling to confirm a social-relation-based affection-driven model (SRAM). SRAM hypothesized relationships among students' perceived social relationships in…
Jen, Tsung-Hau; Lee, Che-Di; Chien, Chin-Lung; Hsu, Ying-Shao; Chen, Kuan-Ming
Review of Sample Size for Structural Equation Models in Second Language Testing and Learning Research: A Monte Carlo Approach
The importance of sample size, although widely discussed in the literature on structural equation modeling (SEM), has not been widely recognized among applied SEM researchers. To narrow this gap, we focus on second language testing and learning studies and examine the following: (a) Is the sample size sufficient in terms of precision and power of…
Maximum Likelihood Methods in Treating Outliers and Symmetrically Heavy-Tailed Distributions for Nonlinear Structural Equation Models with Missing Data
By means of more than a dozen user friendly packages, structural equation models (SEMs) are widely used in behavioral, education, social, and psychological research. As the underlying theory and methods in these packages are vulnerable to outliers and distributions with longer-than-normal tails, a fundamental problem in the field is the…
Applying Structural Equation Models to Study the Influence of Leadership, Total Quality Management, and the Organizational Commitment
This research investigates the implementation between leadership style, total quality management (TQM), and organizational commitment as well as strength of their manifest indicator. Based on recent literatures, this research using structural equation modeling to develop a framework. Using data collected from 376 TQM participants in high-tech industries, the empirical results indicate that strong and positive relationship between leadership style, TQM,
Wen-Hai Chih; Yu-An Lin
Doubly-Latent Models of School Contextual Effects: Integrating Multilevel and Structural Equation Approaches to Control Measurement and Sampling Error
This article is a methodological-substantive synergy. Methodologically, we demonstrate latent-variable contextual models that integrate structural equation models (with multiple indicators) and multilevel models. These models simultaneously control for and unconfound measurement error due to sampling of items at the individual (L1) and group (L2)…
Marsh, Herbert W.; Ludtke, Oliver; Robitzsch, Alexander; Trautwein, Ulrich; Asparouhov, Tihomir; Muthen, Bengt; Nagengast, Benjamin
Relative Performance of Rescaling and Resampling Approaches to Model Chi Square and Parameter Standard Error Estimation in Structural Equation Modeling.
Though common structural equation modeling (SEM) methods are predicated upon the assumption of multivariate normality, applied researchers often find themselves with data clearly violating this assumption and without sufficient sample size to use distribution-free estimation methods. Fortunately, promising alternatives are being integrated into…
Nevitt, Johnathan; Hancock, Gregory R.
The Best of Both Worlds: Factor Analysis of Dichotomous Data Using Item Response Theory and Structural Equation Modeling
Both structural equation modeling (SEM) and item response theory (IRT) can be used for factor analysis of dichotomous item responses. In this case, the measurement models of both approaches are formally equivalent. They were refined within and across different disciplines, and make complementary contributions to central measurement problems…
Glockner-Rist, Angelika; Hoijtink, Herbert
A Structural Equation Modeling Approach for the Analysis of Cortisol Data Collected Using Pre-Post-Post Designs
This study introduces a novel application of structural equation modeling (SEM) for the analysis of cortisol data that are collected using a pre-post-post design. By way of an extended example, an SEM model is developed that permits an examination of both the overall level of cortisol, as well as changes in cortisol (reactivity and regulation), as…
Willoughby, Michael; Vandergrift, Nathan; Blair, Clancy; Granger, Douglas A.
Do Test Design and Uses Influence Test Preparation? Testing a Model of Washback with Structural Equation Modeling
This study introduces Expectancy-value motivation theory to explain the paths of influences from perceptions of test design and uses to test preparation as a special case of washback on learning. Based on this theory, two conceptual models were proposed and tested via Structural Equation Modeling. Data collection involved over 870 test takers of…
Xie, Qin; Andrews, Stephen
Modeling Latent Growth Curves With Incomplete Data Using Different Types of Structural Equation Modeling and Multilevel Software
This article offers different examples of how to fit latent growth curve (LGC) models to longitudinal data using a variety of different software programs (i.e., LISREL, Mx, Mplus, AMOS, SAS). The article shows how the same model can be fitted using both structural equation modeling and multilevel software, with nearly identical results, even in…
Ferrer, Emilio; Hamagami, Fumiaki; McArdle, John J.
Structural Equation Modeling with AMOS, EQS, and LISREL: Comparative Approaches to Testing for the Factorial Validity of a Measuring Instrument.
Uses a confirmatory factor analytic (CFA) model as a paradigmatic basis for the comparison of three widely used structural equation modeling computer programs: (1) AMOS 4.0; (2) EQS 6; and (3) LISREL 8. Comparisons focus on aspects of programs that bear on the specification and testing of CFA models and the treatment of incomplete, nonnormally…
Byrne, Barbara M.
A multi-group structural equation model (SEM) examining asset holding effects on educational attainment by race and gender
Little is known about the processes through which parents' and children's wealth may influence children's math and reading scores. Even less is known about how these processes may vary across race and gender. In this study we analyze Panel Study of Income Dynamics (PSID) data using multi-group structural equation modeling (SEM) to examine wealth effects by gender (male\\/female) and race
William Elliott; Hyunzee Jung; Kevin Kim; Gina Chowa
Use of Structural Equation Modeling to Test the Construct Validity of the SF36 Health Survey in Ten Countries
A crucial prerequisite to the use of the SF-36 Health Survey in multinational studies is the reproduction of the conceptual model underlying its scoring and interpretation. Structural equation modeling (SEM) was used to test these aspects of the construct validity of the SF-36 in ten IQOLA countries: Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden, the United Kingdom, and
Susan D. Keller; John E. Ware; Peter M. Bentler; Neil K. Aaronson; Jordi Alonso; Giovanni Apolone; Jakob B. Bjorner; John Brazier; Monika Bullinger; Stein Kaasa; Alain Leplčge; Marianne Sullivan; Barbara Gandek
Do homes that are more energy efficient consume less energy?: A structural equation model of the English residential sector
Energy consumption from the residential sector is a complex socio-technical problem that can be explained using a combination of physical, demographic and behavioural characteristics of a dwelling and its occupants. A structural equation model (SEM) is introduced to calculate the magnitude and significance of explanatory variables on residential energy consumption. The benefit of this approach is that it explains the
Scott Kelly
Construct Validation of the Peabody Picture Vocabulary Test--Revised: A Structural Equation Model of the Acquisition Order of Words.
A historicodevelopmental model of acquisition order of words was applied to 175 words comprising the Peabody Picture Vocabulary Test--Revised. A structural equation model demonstrates that the combination of date of entry into English, word length, polysemy, and frequency of use account for a substantial proportion of variance of acquisition…
Miller, Linda T.; Lee, Christopher J.
Perfectionism, academic burnout and engagement among Chinese college students: A structural equation modeling analysis
This study aims at identifying the association between perfectionism, academic burnout and engagement in college students. A dual-process model was tested in which negative perfectionism (doubts about actions, concerns over mistakes, et al.) were related to burnout symptoms while positive perfectionism (personal standards and organization) to engagement. A sample of Chinese undergraduates (N=482) completed a battery of questionnaires including the
Yiwen Zhang; Yiqun Gan; Heining Cham
Filipino Nursing Students' Behavioral Intentions toward Geriatric Care: A Structural Equation Model (SEM)
Anchored on the key constucts of Ajzen's Theory of Planned Behavior (1985), this paper seeks to test a model that explores the influence of knowledge, attitude, and caring behavior on nursing students' behavioral intention toward geriatric care. A five-part survey-questionnaire was administered to 839 third and fourth year nursing students from a…
de Guzman, Allan B.; Jimenez, Benito Christian B.; Jocson, Kathlyn P.; Junio, Aileen R.; Junio, Drazen E.; Jurado, Jasper Benjamin N.; Justiniano, Angela Bianca F.
DirectLiNGAM: A direct method for learning a linear non-Gaussian structural equation model
Structural equation models and Bayesian networks have been widely used to analyze causal relations between continuous variables. In such frameworks, linear acyclic models are typically used to model the data-generating process of variables. Recently, it was shown that use of non-Gaussianity identifies the full structure of a linear acyclic model, i.e., a causal ordering of variables and their connection strengths,
Shohei Shimizu; Takanori Inazumi; Yasuhiro Sogawa; Aapo Hyvarinen; Yoshinobu Kawahara; Takashi Washio; Patrik O. Hoyer; Kenneth Bollen
Multi-matrix loop equations: algebraic & differential structures and an approximation based on deformation quantization
Large-N multi-matrix loop equations are formulated as quadratic difference equations in concatenation of gluon correlations. Though non-linear, they involve highest rank correlations linearly. They are underdetermined in many cases. Additional linear equations for gluon correlations, associated to symmetries of action and measure are found. Loop equations aren't differential equations as they involve left annihilation, which doesn't satisfy the Leibnitz rule with concatenation. But left annihilation is a derivation of the commutative shuffle product. Moreover shuffle and concatenation combine to define a bialgebra. Motivated by deformation quantization, we expand concatenation around shuffle in powers of q, whose physical value is 1. At zeroth order the loop equations become quadratic PDEs in the shuffle algebra. If the variation of the action is linear in iterated commutators of left annihilations, these quadratic PDEs linearize by passage to shuffle reciprocal of correlations. Remarkably, this is true for regularized versions of the Yang-Mills, Chern-Simons and Gaussian actions. But the linear equations are underdetermined just as the loop equations were. For any particular solution, the shuffle reciprocal is explicitly inverted to get the zeroth order gluon correlations. To go beyond zeroth order, we find a Poisson bracket on the shuffle algebra and associative q-products interpolating between shuffle and concatenation. This method, and a complementary one of deforming annihilation rather than product are shown to give over and underestimates for correlations of a gaussian matrix model.
Krishnaswami, Govind S.
The influence of locus of control on self-rated health in context of chronic disease: a structural equation modeling approach in a cross sectional study
Background Self-rated health is a robust predictor of several health outcomes, such as functional ability, health care utilization, morbidity and mortality. The purpose of this study is to investigate and explore how health locus of control and disease burden relate to self-rated health among patients at risk for cardiovascular disease. Methods In 2009, 414 Swedish patients who were using statins completed a questionnaire about their health, diseases and their views on the three-dimensional health locus of control scale. The scale determines which category of health locus of control – internal, chance or powerful others – a patient most identifies with. The data was analyzed using logistic regression and a structural equation modeling approach. Results The analyses showed positive associations between internal health locus of control and self-rated health, and a negative association between health locus of control in chance and powerful others and self-rated health. High internal health locus of control was negatively associated with the cumulative burden of diseases, while health locus of control in chance and powerful others were positively associated with burden of diseases. In addition, age and education level had indirect associations with self-rated health through health locus of control. Conclusions This study suggests that self-rated health is positively correlated with internal locus of control and negatively associated with high locus of control in chance and powerful others in patients at high risk for cardiovascular disease. Furthermore, disease burden seems to be negatively associated with self-rated health.
A further exploration of sensation seeking propensity, reward sensitivity, depression, anxiety, and the risky behaviour of young novice drivers in a structural equation model.
Young novice drivers constitute a major public health concern due to the number of crashes in which they are involved, and the resultant injuries and fatalities. Previous research suggests psychological traits (reward sensitivity, sensation seeking propensity), and psychological states (anxiety, depression) influence their risky behaviour. The relationships between gender, anxiety, depression, reward sensitivity, sensation seeking propensity and risky driving are explored. Participants (390 intermediate drivers, 17-25 years) completed two online surveys at a six month interval. Surveys comprised sociodemographics, Brief Sensation Seeking Scale, Kessler's Psychological Distress Scale, an abridged Sensitivity to Reward Questionnaire, and risky driving behaviour was measured by the Behaviour of Young Novice Drivers Scale. Structural equation modelling revealed anxiety, reward sensitivity and sensation seeking propensity predicted risky driving. Gender was a moderator, with only reward sensitivity predicting risky driving for males. Future interventions which consider the role of rewards, sensation seeking, and mental health may contribute to improved road safety for younger and older road users alike. PMID:22770376
Scott-Parker, Bridie; Watson, Barry; King, Mark J; Hyde, Melissa K
Psychometric Evaluation of the Chinese Virtues Questionnaire
Objectives: The present study examined the psychometric properties of the Chinese Virtues Questionnaire (CVQ). The reliability, factor structure, construct validity, and temporal stability of the inventory were examined. Method: A university student sample ("n" = 878) and a working adult sample ("n" = 153) were recruited.…
Duan, Wenjie; Ho, Samuel M. Y.; Bai, Yu; Tang, Xiaoqing
Construct Validity of the Social Coping Questionnaire
The Social coping Questionnaire (SCQ) measures strategies used by gifted adolescents to minimize the negative effect they believe their high ability has on their social interactions. Previous studies have supported the factor structure, internal consistency, and test-retest reliability of the SCQ. The current study provides construct validity…
Swiatek, Mary Ann; Cross, Tracy L.
Reliability of the Suicide Opinion Questionnaire.
The lack of systematic psychometric information on the Suicide Opinion Questionnaire (SOQ) was addressed by investigating the factor structure and reliability of the eight-factor clinical scale model (mental illness, cry for help, right to die, religion, impulsivity, normality, aggression, and moral evil), developed for interpreting responses to…
Rogers, James R.; DeShon, Richard P.
Background Higher levels of impulsivity have been implicated in the development of alcohol use disorders. Recent findings suggest that impulsivity is not a unitary construct, highlighted by the diverse ways in which the various measures of impulsivity relate to alcohol use outcomes. This study simultaneously tested the following dimensions of impulsivity as determinants of alcohol use and alcohol problems: risky decision-making, self-reported risk attitudes, response inhibition, and impulsive decision-making. Method Participants were a community sample of non-treatment seeking problem drinkers (N = 158). Structural Equation Modeling (SEM) analyses employed behavioral measures of impulsive decision-making (Delay Discounting Task, DDT), response inhibition (Stop Signal Task, SST), and risky decision-making (Balloon Analogue Risk Task, BART), and a self-report measure of risk attitudes (Domain-specific Risk-attitude Scale, DOSPERT), as predictors of alcohol use and of alcohol-related problems in this sample. Results The model fit well, accounting for 38% of the variance in alcohol problems, and identified two impulsivity dimensions that significantly loaded onto alcohol outcomes: (1) impulsive decision-making, indexed by the DDT; and (2) risky decision-making, measured by the BART. Conclusions The impulsive decision-making dimension of impulsivity, indexed by the DDT, was the strongest predictor of alcohol use and alcohol pathology in this sample of problem drinkers. Unexpectedly, a negative relationship was found between risky decision-making and alcohol problems. The results highlight the importance of considering the distinct facets of impulsivity in order to elucidate their individual and combined effects on alcohol use initiation, escalation, and dependence.
Courtney, Kelly E.; Arellano, Ryan; Barkley-Levenson, Emily; Galvan, Adriana; Poldrack, Russell A.; MacKillop, James; Jentsch, J. David; Ray, Lara A.
Smoking behaviours and cessation services among male physicians in China: evidence from a structural equation model
Objective To investigate smoking prevalence and cessation services provided by male physicians in hospitals in three Chinese cities. Methods Data were collected from a survey of male physicians employed at 33 hospitals in Changsha, Qingdao and Wuxi City (n=720). Exploratory factor analysis was performed to identify latent variables, and confirmatory structural equation modelling analysis was performed to test the relationships between predictor variables and smoking in male physicians, and their provision of cessation services. Results Of the sampled male physicians, 25.7% were current smokers, and 54.0% provided cessation services by counselling (18.8%), distributing self-help materials (17.1%), and providing traditional remedies or medication (18.2%). Factors that predicted smoking included peer smoking (OR 1.14 95% CI 1.03 to 1.26) and uncommon knowledge (OR 0.94 95% CI 0.89 to 0.99), a variable measuring awareness of the association of smoking with stroke, heart attack, premature ageing and impotence in male adults as well as the role of passive smoking in heart attack. Factors that predicted whether physicians provided smoking cessation services included peer smoking (OR 0.82 95% CI 0.76 to 0.89), physicians' own smoking (OR 0.87 95% CI 0.81 to 0.93), training in cessation (OR 1.36 95% CI 1.27 to 1.45) and access to smoking cessation resources (OR 1.69 95% CI 1.58 to 1.82). Conclusions The smoke-free policy is not strictly implemented at healthcare facilities, and smoking remains a public health problem among male physicians. A holistic approach, including a stricter implementation of the smoke-free policy, comprehensive education on the hazards of smoking, training in standard smoking-cessation techniques and provision of cessation resources, is needed to curb the smoking epidemic among male physicians and to promote smoking cessation services in China.
Huang, Cheng; Guo, Chaoran; Yu, Shaohua; Feng, Yan; Song, Julia; Eriksen, Michael; Redmon, Pam; Koplan, Jeffrey
Inferring transcriptional compensation interactions in yeast via stepwise structure equation modeling
Background With the abundant information produced by microarray technology, various approaches have been proposed to infer transcriptional regulatory networks. However, few approaches have studied subtle and indirect interaction such as genetic compensation, the existence of which is widely recognized although its mechanism has yet to be clarified. Furthermore, when inferring gene networks most models include only observed variables whereas latent factors, such as proteins and mRNA degradation that are not measured by microarrays, do participate in networks in reality. Results Motivated by inferring transcriptional compensation (TC) interactions in yeast, a stepwise structural equation modeling algorithm (SSEM) is developed. In addition to observed variables, SSEM also incorporates hidden variables to capture interactions (or regulations) from latent factors. Simulated gene networks are used to determine with which of six possible model selection criteria (MSC) SSEM works best. SSEM with Bayesian information criterion (BIC) results in the highest true positive rates, the largest percentage of correctly predicted interactions from all existing interactions, and the highest true negative (non-existing interactions) rates. Next, we apply SSEM using real microarray data to infer TC interactions among (1) small groups of genes that are synthetic sick or lethal (SSL) to SGS1, and (2) a group of SSL pairs of 51 yeast genes involved in DNA synthesis and repair that are of interest. For (1), SSEM with BIC is shown to outperform three Bayesian network algorithms and a multivariate autoregressive model, checked against the results of qRT-PCR experiments. The predictions for (2) are shown to coincide with several known pathways of Sgs1 and its partners that are involved in DNA replication, recombination and repair. In addition, experimentally testable interactions of Rad27 are predicted. Conclusion SSEM is a useful tool for inferring genetic networks, and the results reinforce the possibility of predicting pathways of protein complexes via genetic interactions.
Shieh, Grace S; Chen, Chung-Ming; Yu, Ching-Yun; Huang, Juiling; Wang, Woei-Fuh; Lo, Yi-Chen
Analysing the socioeconomic determinants of hypertension in South Africa: a structural equation modelling approach
Background Epidemiological research has long observed a varying prevalence of hypertension across socioeconomic strata. However, patterns of association and underlying causal mechanisms are poorly understood in sub-Saharan Africa. Using education and income as indicators, we investigated the extent to which socioeconomic status is linked to blood pressure in the first wave of the National Income Dynamics Study — a South African longitudinal study of more than 15000 adults – and whether bio-behavioural risk factors mediate the association. Methods In a cross-sectional analysis, structural equation modelling was employed to estimate the effect of socioeconomic status on systolic and diastolic blood pressure and to assess the role of a set of bio-behavioural risk factors in explaining the observed relationships. Results After adjustment for age, race and antihypertensive treatment, higher education and income were independently associated with higher diastolic blood pressure in men. In women higher education predicted lower values of both diastolic and systolic blood pressure while higher income predicted lower systolic blood pressure. In both genders, body mass index was a strong mediator of an adverse indirect effect of socioeconomic status on blood pressure. Together with physical exercise, alcohol use, smoking and resting heart rate, body mass index therefore contributed substantially to mediation of the observed relationships in men. By contrast, in women unmeasured factors played a greater role. Conclusion In countries undergoing epidemiological transition, effects of socioeconomic status on blood pressure may vary by gender. In women, factors other than those listed above may have substantial role in mediating the association and merit investigation.
Connectivity analysis with structural equation modelling: an example of the effects of voxel selection.
Structural equation modelling (SEM) of neuroimaging data is commonly applied to a network of distributed brain regions. We applied SEM to an fMRI dataset to identify condition-specific effects in a simple experiment composed of visual stimulation and baseline conditions. The visual network was composed of three well-defined anatomical regions (V1, V2, and V5) and three path connections (V1 --> V2, V1 --> V5, and V2 --> V5). This network was used to test four hypotheses: (1) whether the condition-specific effects for all three connections vary according to the data selected for modelling; (2) whether the "summary" measures that are often used are indeed appropriate; (3) whether measures taken from the voxel timecourse can reliably predict the condition-specific effects for each one of the three path connections, and (4) whether all voxels within an anatomical region yield equivalent SEM outcomes. There was some variability in the significance of the condition-specific effects across randomly selected voxels within regions. However, the SEM outcome from the "summary" measures was comparable to the most frequent pattern of condition-specific effects. Magnitude, delay, spread, and goodness-of-fit measures taken from a gamma fit to the voxel time courses predicted reliably the significance of the SEM condition-specific effects for each connection. This result enabled us to identify spatially coherent regions at the boundaries of V2 that displayed different condition-specific effects from those seen in the majority of the voxels. Although the generality of these results awaits further investigation, this example highlights a number of important issues for SEM. We have provided further evidence that the SEM outcome does vary somewhat according to the voxels selected and that, although the use of summary measures can give a generalised view of the connectivity pattern, they could fail to capture functional differences within specialised areas. PMID:14642459
Gonçalves, Miguel S; Hall, Deborah A
A structural equation model analysis of postfire plant diversity in California shrublands
This study investigates patterns of plant diversity following wildfires in fire-prone shrublands of California, seeks to understand those patterns in terms of both local and landscape factors, and considers the implications for fire management. Ninety study sites were established following extensive wildfires in 1993, and 1000-m2 plots were used to sample a variety of parameters. Data on community responses were collected for five years following fire. Structural equation modeling (SEM) was used to relate plant species richness to plant abundance, fire severity, abiotic conditions, within-plot heterogeneity, stand age, and position in the landscape. Temporal dynamics of average richness response was also modeled. Richness was highest in the first year following fire, indicating postfire enhancement of diversity. A general decline in richness over time was detected, with year-to-year variation attributable to annual variations in precipitation. Peak richness in the landscape was found where (1) plant abundance was moderately high, (2) within-plot heterogeneity was high, (3) soils were moderately low in nitrogen, high in sand content, and with high rock cover, (4) fire severity was low, and (5) stands were young prior to fire. Many of these characteristics were correlated with position in the landscape and associated conditions. We infer from the SEM results that postfire richness in this system is strongly influenced by local conditions and that these conditions are, in turn, predictably related to landscape-level conditions. For example, we observed that older stands of shrubs were characterized by more severe fires, which were associated with a low recovery of plant cover and low richness. These results may have implications for the use of prescribed fire in this system if these findings extrapolate to prescribed burns as we would expect. ?? 2006 by the Ecological Society of America.
Grace, J. B.; Keeley, J. E.
Neurocognition, Insight and Medication Nonadherence in Schizophrenia: A Structural Equation Modeling Approach
Objective The aim of this study was to examine the complex relationships among neurocognition, insight and nonadherence in patients with schizophrenia. Methods Design: Cross-sectional study. Inclusion criteria: Diagnosis of schizophrenia according to the DSM-IV-TR criteria. Data collection: Neurocognition was assessed using a global approach that addressed memory, attention, and executive functions; insight was analyzed using the multidimensional 'Scale to assess Unawareness of Mental Disorder;' and nonadherence was measured using the multidimensional 'Medication Adherence Rating Scale.' Analysis: Structural equation modeling (SEM) was applied to examine the non-straightforward relationships among the following latent variables: neurocognition, 'awareness of positive symptoms' and 'negative symptoms', 'awareness of mental disorder' and nonadherence. Results One hundred and sixty-nine patients were enrolled. The final testing model showed good fit, with normed ?2?=?1.67, RMSEA?=?0.063, CFI?=?0.94, and SRMR?=?0.092. The SEM revealed significant associations between (1) neurocognition and 'awareness of symptoms,' (2) 'awareness of symptoms' and 'awareness of mental disorder' and (3) 'awareness of mental disorder' and nonadherence, mainly in the 'attitude toward taking medication' dimension. In contrast, there were no significant links between neurocognition and nonadherence, neurocognition and 'awareness of mental disorder,' and 'awareness of symptoms' and nonadherence. Conclusions Our findings support the hypothesis that neurocognition influences 'awareness of symptoms,' which must be integrated into a higher level of insight (i.e., the 'awareness of mental disorder') to have an impact on nonadherence. These findings have important implications for the development of effective strategies to enhance medication adherence.
Boyer, Laurent; Cermolacce, Michel; Dassa, Daniel; Fernandez, Jessica; Boucekine, Mohamed; Richieri, Raphaelle; Vaillant, Florence; Dumas, Remy; Auquier, Pascal; Lancon, Christophe
The Marks Asthma Quality of Life Questionnaire
We performed analyses to examine the structure, validity, and responsiveness to change of the Marks Asthma Quality of Life Questionnaire (AQLQ), originally validated in Australia in a self-administered format, among 539 U.S. subjects with asthma. Subjects were interviewed twice by telephone over an 18-month period. Based on factor analyses, the subscale structure of the AQLQ was modified slightly to eliminate
Patricia P. Katz; Mark D. Eisner; Jonathan Henke; Stephen Shiboski; Edward H. Yelin; Paul D. Blanc
Equation poems
One of the most challenging goals of a physics teacher is to help students see that the equations of physics are connected to each other, and that they logically unfold from a small number of basic ideas. Derivations contain the vital information on this connective structure. In a traditional physics course, there are many problem-solving exercises, but few, if any, derivation exercises. Creating an equation poem is an exercise to help students see the unity of the equations of physics, rather than their diversity. An equation poem is a highly refined and eloquent set of symbolic statements that captures the essence of the derivation of an equation. Such a poetic derivation is uncluttered by the extraneous details that tend to distract a student from understanding the essential physics of the long, formal derivation.
Prentis, Jeffrey J.
The Attitudes to Ageing Questionnaire: Mokken Scaling Analysis
Background Hierarchical scales are useful in understanding the structure of underlying latent traits in many questionnaires. The Attitudes to Ageing Questionnaire (AAQ) explored the attitudes to ageing of older people themselves, and originally described three distinct subscales: (1) Psychosocial Loss (2) Physical Change and (3) Psychological Growth. This study aimed to use Mokken analysis, a method of Item Response Theory, to test for hierarchies within the AAQ and to explore how these relate to underlying latent traits. Methods Participants in a longitudinal cohort study, the Lothian Birth Cohort 1936, completed a cross-sectional postal survey. Data from 802 participants were analysed using Mokken Scaling analysis. These results were compared with factor analysis using exploratory structural equation modelling. Results Participants were 51.6% male, mean age 74.0 years (SD 0.28). Three scales were identified from 18 of the 24 items: two weak Mokken scales and one moderate Mokken scale. (1) 'Vitality' contained a combination of items from all three previously determined factors of the AAQ, with a hierarchy from physical to psychosocial; (2) 'Legacy' contained items exclusively from the Psychological Growth scale, with a hierarchy from individual contributions to passing things on; (3) 'Exclusion' contained items from the Psychosocial Loss scale, with a hierarchy from general to specific instances. All of the scales were reliable and statistically significant with 'Legacy' showing invariant item ordering. The scales correlate as expected with personality, anxiety and depression. Exploratory SEM mostly confirmed the original factor structure. Conclusions The concurrent use of factor analysis and Mokken scaling provides additional information about the AAQ. The previously-described factor structure is mostly confirmed. Mokken scaling identifies a new factor relating to vitality, and a hierarchy of responses within three separate scales, referring to vitality, legacy and exclusion. This shows what older people themselves consider important regarding their own ageing.
Shenkin, Susan D.; Watson, Roger; Laidlaw, Ken; Starr, John M.; Deary, Ian J.
Validating a Writing Strategy Questionnaire.
Focuses on the validation of a writing strategies questionnaire and presents the various stages in the validation process. The questionnaire was validated using a qualitative and quantitative method with two groups of participants from the target population--advanced nonnative speakers of English. (VWL)
Petric, Bojana; Czarl, Bernadett
This article is a methodological-substantive synergy. Methodologically, we demonstrate latent-variable contextual models that integrate structural equation models (with multiple indicators) and multilevel models. These models simultaneously control for and unconfound measurement error due to sampling of items at the individual (L1) and group (L2) levels and sampling error due the sampling of persons in the aggregation of L1 characteristics to
Herbert W. Marsh; Oliver Lüdtke; Alexander Robitzsch; Ulrich Trautwein; Tihomir Asparouhov; Bengt Muthén; Benjamin Nagengast
Testing the Cognitive Content-Specificity Hypothesis of Social Anxiety and Depression: An Application of Structural Equation Modeling
The present research examined three key issues of the cognitive content-specificity hypothesis of social anxiety and depression using structural equation modeling (SEM) approach. First, using confirmatory factor analyses on data from a sample of 507 undergraduate students, we found that both positive and negative self-statements factors of the modified Social Interaction Self-Statement Test were empirically differentiated from those of the
Yongrae Cho; Michael J. Telch
Assuming only that the spectra of A and B are disjoint as opposed to the more restrictive assumption previously used, we obtain a bound in all unitarily invariant norms on the solution to the structured Sylvester equation AXˇXB =A1=2EB1=2. This bound is the rst of its kind in all unitarily invariant norms under only the disjointedness assumption. An application of
Multidisciplinary Treatment Planning Questionnaire
Multidisciplinary care, which incorporates Multidisciplinary Treatment Planning (MTP), is increasingly being adopted within oncology care settings with the intent of enhancing the quality of care delivered to patients. However, what is not known is its impact on improving patient outcomes and the quality of care being delivered. A targeted review of the literature was conducted to examine the organization and operation of the Multidisciplinary Care (MDC) team structure1. Findings revealed that a variety of implementation models exist within the health care system.
The higher grading structure of the WKI hierarchy and the two-component short pulse equation
A higher grading affine algebraic construction of integrable hierarchies, containing the Wadati-Konno-Ichikawa (WKI) hierarchy as a particular case, is proposed. We show that a two-component generalization of the Schäfer-Wayne short pulse equation arises quite naturally from the first negative flow of the WKI hierarchy. Some novel integrable nonautonomous models are also proposed. The conserved charges, both local and nonlocal, are obtained from the Riccati form of the spectral problem. The loop-soliton solutions of the WKI hierarchy are systematically constructed through gauge followed by reciprocal Bäcklund transformation, establishing the precise connection between the whole WKI and AKNS hierarchies. The connection between the short pulse equation with the sine-Gordon model is extended to a correspondence between the two-component short pulse equation and the Lund-Regge model.
A comparison of several approaches for choosing between working correlation structures in generalized estimating equation analysis of longitudinal binary data.
The method of generalized estimating equations (GEE) models the association between the repeated observations on a subject with a patterned correlation matrix. Correct specification of the underlying structure is a potentially beneficial goal, in terms of improving efficiency and enhancing scientific understanding. We consider two sets of criteria that have previously been suggested, respectively, for selecting an appropriate working correlation structure, and for ruling out a particular structure(s), in the GEE analysis of longitudinal studies with binary outcomes. The first selection criterion chooses the structure for which the model-based and the sandwich-based estimator of the covariance matrix of the regression parameter estimator are closest, while the second selection criterion chooses the structure that minimizes the weighted error sum of squares. The rule out criterion deselects structures for which the estimated correlation parameter violates standard constraints for binary data that depend on the marginal means. In addition, we remove structures from consideration if their estimated parameter values yield an estimated correlation structure that is not positive definite. We investigate the performance of the two sets of criteria using both simulated and real data, in the context of a longitudinal trial that compares two treatments for major depressive episode. Practical recommendations are also given on using these criteria to aid in the efficient selection of a working correlation structure in GEE analysis of longitudinal binary data. PMID:19472307
Shults, Justine; Sun, Wenguang; Tu, Xin; Kim, Hanjoo; Amsterdam, Jay; Hilbe, Joseph M; Ten-Have, Thomas
Doubly periodic wave structures of the (2+1)-dimensional Nizhnik-Novikov-Veselov equation
A mapping approach is suggested to solve the (2+1)-dimensional Nizhnik-Novikov-Veselov equation, three families of solutions (including solitary wave solutions, periodic wave solutions and rational function solutions) with two arbitrary functions are obtained, among which two sets of wave packets are expressed as rational functions of the Jacobi elliptic functions.
Ma, Z. Y.; Hu, Y. H.
Elaborated constitutive equations for structural analysis for creep, swelling, and damage under irradiation
This paper reports on the constitutive equations for creep, swelling, and damage under irradiation discussed in terms of incorporating the transient behavior of swelling after the incubation fluence as well as the effect of transient creep. Creep during irradiation is assumed to consist of irradiation-induced creep and irradiation-affected thermal creep, and the dilatational part of irradiation-induced creep is identified with swelling. The irradiation-induced creep is formulated by postulating the stress-induced preferential absorption mechanism. Then, the continuous transition of swelling after the incubation fluence is formulated using the curvature parameter of Bates and Korenko. For transient creep, on the other hand, the McVetty creep law and the Kachanov-Rabotnov creep damage theory are modified to describe irradiation-affected thermal creep. The resulting equations are applied to predict creep before, during, and after irradiation of 20% cold-worked Type 316 stainless steel at elevated temperatures, and the validity of the equations is discussed by comparison with experiments. Finally, the bulging and rupture process in fast breeder reactor fuel cladding is analyzed using the equations.
Murakami, S.; Mizuno, M. (Nagoya Univ., Dept. of Mechanical Engineering, Furo-cho, Chikusa-ku, Nagoya, 464-01 (JP))
Determinant Structure of the Rational Solutions for the Painlev\\\\'e IV Equation
Rational solutions for the Painlev\\\\'e IV equation are investigated by Hirota bilinear formalism. It is shown that the solutions in one hierarchy are expressed by 3-reduced Schur functions, and those in another two hierarchies by Casorati determinant of the Hermite polynomials, or by special case of the Schur polynomials.
Kenji Kajiwara; Yasuhiro Ohta
Structure of Polymer Melts and Blends: Comparison of Integral Equation Theory and Computer Simulations
This review covers the most recent developments using the Polymer Reference Interaction Site Model (PRISM) integral equation theory to study polymer melts and blends. Comparisons to computer simulations are presented that have isolated the deficiencies in the theory and led to improvements including the self-consistent approach where the theory is coupled with single chain Monte Carlo simulations. Using recent simulation
David R. Heine; Gary S. Grest; John G. Curro
Electronic structure and equation of state data of warm dense gold
Equation of state data and electrical resistivity of warm dense gold were measured in the internal energy range 8-12 MJ/kg. Experimental results were compared with quantum molecular dynamics simulations. The theoretical results match well the experimental data, allowing a detailed interpretation of the theoretical thermodynamic properties and frequency-dependent conductivities.
Renaudin, P.; Recoules, V.; Noiret, P.; Clerouin, J. [Departement de Physique Theorique et Appliquee, CEA/DAM Ile-de-France, BP12, 91680 Bruyeres-le-Chatel Cedex (France)
Structure and Gevrey asymptotic of solutions representing topological defects to some partial differential equations
We consider the positive real-valued solutions of a particular type of ordinary differential equations that arise when considering defect solutions to semilinear partial differential equations. We provide sufficient conditions on the nonlinear term to ensure the existence, uniqueness and monotonicity of solutions to the ordinary differential equation with the prescribed boundary conditions. We then focus on the behaviour of such solutions at infinity and we prove that there is a unique formal expansion at infinity of the Gevrey type, i.e. the coefficients of the expansion grow as a power of a factorial. Moreover, we show that the actual solution is indeed asymptotic 1-Gevrey to this formal expansion. We also present a numerical algorithm to compute the solution for arbitrary values of the degree n in the particular case of the Ginzburg-Landau equation. In particular, we address the difficulty in the numerical computations when n is relatively large due to the fact that the shooting parameter becomes exponentially small for the whole class of nonlinearities considered in this work.
Aguareles, M.; Baldomá, I.
In recent years significant advances have been made for parallel computers in both hardware and software. Now parallel computers have become viable tools in computational mechanics. Many application codes developed on conventional computers have been modified to benefit from parallel computers. Significant speedups in some areas have been achieved by parallel computations. For single-discipline use of both fluid dynamics and structural dynamics, computations have been made on wing-body configurations using parallel computers. However, only a limited amount of work has been completed in combining these two disciplines for multidisciplinary applications. The prime reason is the increased level of complication associated with a multidisciplinary approach. In this work, procedures to compute aeroelasticity on parallel computers using direct coupling of fluid and structural equations will be investigated for wing-body configurations. The parallel computer selected for computations is an Intel iPSC/860 computer which is a distributed-memory, multiple-instruction, multiple data (MIMD) computer with 128 processors. In this study, the computational efficiency issues of parallel integration of both fluid and structural equations will be investigated in detail. The fluid and structural domains will be modeled using finite-difference and finite-element approaches, respectively. Results from the parallel computer will be compared with those from the conventional computers using a single processor. This study will provide an efficient computational tool for the aeroelastic analysis of wing-body structures on MIMD type parallel computers.
Byun, Chansup; Guruswamy, Guru P.; Kutler, Paul (Technical Monitor)
Construct Validity of the Children's Music-Related Behavior Questionnaire
The purpose of this research was to investigate the construct validity of the Children's Music-Related Behavior Questionnaire (CMRBQ), an instrument designed for parents to document music-related behaviors about their children and themselves. The research problem was to examine the hypothesized factorial structure of the questionnaire. From a…
Valerio, Wendy H.; Reynolds, Alison M.; Morgan, Grant B.; McNair, Anne A.
Band structure of photonic crystal with dispersive and lossy materials using Dirichlet-to-Neumann wave vector eigen equation method
We present the Dirichlet-to-Neumann wave vector eigen equation (DtN-WVEE) method to calculate the band structure of photonic crystal (PhC) with dispersive and lossy materials, and then use finite-difference time-domain method to verify the validity of the results of the DtN-WVEE method. Since the material is lossy with a non-zero imaginary part of epsilon, the wave vector of PhC band structure also has a non-zero imaginary part which results in the reduction of the intensity of the mode. We further present the band structure which gives the relationship among the normalized frequency, the real part of the wave vector, and the imaginary part of the wave vector. To our knowledge, the band structure of lossy PhC has not been well studied yet, and our results can be useful in designing the devices using surface plasmon polariton effect.
Jiang, Bin; Zhang, Yejin; Wang, Yufei; Zheng, Wanhua
Key Person Questionnaire Baseline Analysis.
The report is from a USAC series produced by the Franklin Institute Research Laboratories designed to explore IMIS impacts on city administrative organization and behavior. The Key Person Questionnaire, which forms the basis for this report, examines basi...
S. R. Enion
Physical Activity Questionnaire Search Results
The Brunel Lifestyle Physical Activity Questionnaire a4 If you add together each session of pre-planned physical activity that you engage in during a normal week, how much time would you estimate that you spend in total?
Causal structure of oscillations in gene regulatory networks: Boolean analysis of ordinary differential equation attractors
A common approach to the modeling of gene regulatory networks is to represent activating or repressing interactions using ordinary differential equations for target gene concentrations that include Hill function dependences on regulator gene concentrations. An alternative formulation represents the same interactions using Boolean logic with time delays associated with each network link. We consider the attractors that emerge from the two types of models in the case of a simple but nontrivial network: a figure-8 network with one positive and one negative feedback loop. We show that the different modeling approaches give rise to the same qualitative set of attractors with the exception of a possible fixed point in the ordinary differential equation model in which concentrations sit at intermediate values. The properties of the attractors are most easily understood from the Boolean perspective, suggesting that time-delay Boolean modeling is a useful tool for understanding the logic of regulatory networks.
Sun, Mengyang; Cheng, Xianrui; Socolar, Joshua E. S.
The solution of linear systems of equations with a structural analysis code on the NAS CRAY-2
Two methods for solving linear systems of equations on the NAS Cray-2 are described. One is a direct method; the other is an iterative method. Both methods exploit the architecture of the Cray-2, particularly the vectorization, and are aimed at structural analysis applications. To demonstrate and evaluate the methods, they were installed in a finite element structural analysis code denoted the Computational Structural Mechanics (CSM) Testbed. A description of the techniques used to integrate the two solvers into the Testbed is given. Storage schemes, memory requirements, operation counts, and reformatting procedures are discussed. Finally, results from the new methods are compared with results from the initial Testbed sparse Choleski equation solver for three structural analysis problems. The new direct solvers described achieve the highest computational rates of the methods compared. The new iterative methods are not able to achieve as high computation rates as the vectorized direct solvers but are best for well conditioned problems which require fewer iterations to converge to the solution.
Poole, Eugene L.; Overman, Andrea L.
This paper reports on the constitutive equations for creep, swelling, and damage under irradiation discussed in terms of incorporating the transient behavior of swelling after the incubation fluence as well as the effect of transient creep. Creep during irradiation is assumed to consist of irradiation-induced creep and irradiation-affected thermal creep, and the dilatational part of irradiation-induced creep is identified with
S. Murakami; M. Mizuno
The Hamiltonian structure of Dirac's equation in tensor form and its Fermi quantization
Currently, there is some interest in studying the tensor forms of the Dirac equation to elucidate the possibility of the constrained tensor fields admitting Fermi quantization. We demonstrate that the bispinor and tensor Hamiltonian systems have equivalent Fermi quantizations. Although the tensor Hamiltonian system is noncanonical, representing the tensor Poisson brackets as commutators for the Heisenberg operators directly leads to Fermi quantization without the use of bispinors.
Reifler, Frank; Morris, Randall