01795nas a2200169 4500008004100000245014100041210006900182300001200251490000700263520113700270653003401407100001401441700001301455700002101468700001401489856012201503 1997 eng d00aThe effect of population distribution and method of theta estimation on computerized adaptive testing (CAT) using the rating scale model0 aeffect of population distribution and method of theta estimation a422-4390 v573 aInvestigated the effect of population distribution on maximum likelihood estimation (MLE) and expected a posteriori estimation (EAP) in a simulation study of computerized adaptive testing (CAT) based on D. Andrich's (1978) rating scale model. Comparisons were made among MLE and EAP with a normal prior distribution and EAP with a uniform prior distribution within 2 data sets: one generated using a normal trait distribution and the other using a negatively skewed trait distribution. Descriptive statistics, correlations, scattergrams, and accuracy indices were used to compare the different methods of trait estimation. The EAP estimation with a normal prior or uniform prior yielded results similar to those obtained with MLE, even though the prior did not match the underlying trait distribution. An additional simulation study based on real data suggested that more work is needed to determine the optimal number of quadrature points for EAP in CAT based on the rating scale model. The choice between MLE and EAP for particular measurement situations is discussed. (PsycINFO Database Record (c) 2003 APA, all rights reserved).10acomputerized adaptive testing1 aChen, S-K1 aHou, L Y1 aFitzpatrick, S J1 aDodd, B G uhttp://iacat.org/content/effect-population-distribution-and-method-theta-estimation-computerized-adaptive-testing-cat