Several psychometric instruments have been adapted to near-death research. Ring developed the Weighted Core Experience Index in order to measure the depth of NDEs, and this instrument has been used by other researchers for this purpose. The instrument has also been used to measure the impact of near-death experiences on dialysis patients. According to some commentators the index has improved the consistency in the field. However, Greyson notes that although the index is a "pioneering effort", it is not based on statistical analysis, and has not been tested for internal coherence or reliability. In 1984 Ring developed an instrument called the Life Changes Inventory (LCI) in order to quantify value changes following an NDE. The instrument was later revised and standardized and a new version, the LCI-R, was published in 2004. Greyson developed The Near-Death Experience Scale. This 16-item Scale was found to have high internal consistency, split-half reliability, and test-retest reliability and was correlated with Ring's Weighted Core Experience Index. Questions formulated by the scale address such dimensions as: cognition (feelings of accelerated thought, or "life-review"), affect (feelings of peace and joy), paranormal experience (feelings of being outside of the body, or a perception of future events) and transcendence (experience of encountering deceased relatives, or experiencing an unearthly realm). A score of 7 or higher out of a possible 32 was used as the standard criterion for a near-death experience. The scale is, according to the author, clinically useful in differentiating NDEs from organic brain syndromes and nonspecific stress responses. The NDE-scale was later found to fit the Rasch rating scale model. The instrument has been used to measure NDEs among cardiac arrest survivors, coma survivors, out-of-hospital cardiac arrest patients/survivors, substance misusers, and dialysis patients. In the late 1980s Thornburg developed the Near-Death Phenomena Knowledge and Attitudes Questionnaire. The questionnaire consists of 23 true/false/undecided response items assessing knowledge, 23 Likert scale items assessing general attitudes toward near-death phenomena, and 20 Likert scale items assessing attitude toward caring for a client who has had an NDE. Content validity was established by using a panel of experts selected from nursing, sociology, and psychology. The instrument was also found to satisfy the criteria for internal consistency. The instrument has been used to measure attitudes toward, and knowledge of, near-death experiences in a college population, among clergy, among registered psychologists, and among hospice nurses. Martial and colleagues developed the Near-Death Experience Content (NDE-C)