validity of the randomized response technique is limited. Nominative and best-friend techniques The nominative technique asks a participant about the behavior of their close friends, rather than about their own behavior. Participants are asked how many close friends they know have done for certain a sensitive behavior and how many other people they think know about that behavior. Population estimates of behaviors can be derived from the response. The similar best-friend methodology asks the participant about the behavior of one best friend. Unmatched-count technique The unmatched-count technique asks respondents to indicate how many of a list of several items they have done or are true for them. Respondents are randomized to receive either a list of non-sensitive items or that same list plus the sensitive item of interest. Differences in the total number of items between the two groups indicate how many of those in the group receiving the sensitive item said yes to it. Grouped-answer method The grouped-answer method, also known as the two-card or three-card method, combines answer choices such that the sensitive response is combined with at least one non-sensitive response option. Crosswise, triangular, and hidden-sensitivity methods These methods ask participants to select one response based on two or more questions, only one of which is sensitive. For example, a participant will be asked whether their birth year is even and whether they have performed an illegal activity; if yes to both or no to both, to select A, and if yes to one but no to the other, select B. By combining sensitive and non-sensitive questions, the participant's response to the sensitive item is masked. Research shows that the validity of the crosswise model is limited. Bogus pipeline Bogus-pipeline techniques are those in which a participant believes that an objective test, like a lie detector, will be used along with survey response, whether or not that test or procedure is actually used. Other response styles "Extreme-response style" (ERS) takes the form of exaggerated-extremity preference, e.g. for '1' or '7' on 7-point scales. Its converse, 'moderacy bias' entails a preference for middle-range (or midpoint) responses (e.g. 3–5 on 7-point scales). "Acquiescence" (ARS) is the tendency to respond to items with agreement/affirmation independent of their content ("yea"-saying). These kinds of response styles differ from social-desirability bias in that they are unrelated to the question's content and may be present in both socially neutral and in socially favorable or