For the six available sets of empirical data, the discrimination (slope) parameter of the logistic item characteristic curve was found to have a significant positive correlation over items with the difficulty (location) parameter. This unpleasant situation can be eliminated by a suitably chosen transformation of the ability scale. (Author/RC)

Given known item parameters for a test, unbiased estimators are derived for an examinee's ability parameter, his or her proportion correct true score for the variances of these parameters and for the parallel forms reliability of the maximum likelihood estimator of the ability parameter. (Author/JKS)

This study investigates whether item characteristic curves are the same for black students as for white students in the United States. The data analyzed were the answer sheets of 2269 black students and 2285 white students taking the 85-item Verbal Section of the College Board's Scholastic Aptitude Test. The study of item characteristic curves is…

Asymptotic formulas are derived for the bias in the maximum likelihood estimators of the item parameters in the logistic item response model when examinee abilities are known. Numerical results are given for a typical verbal test for college admission. (Author)

A number of empirical studies are suggested to answer certain questions in connection with flexilevel tests. (MS)

A common problem arises in scale transformation when independent estimates of item parameters from two separate data sets must be expressed in the same metric. These item parameter estimates will be different because the metric or scale defined by each independent calibration of the items is different. The problem is frequently confronted in…

The purpose of this book is to make it possible for measurement specialists to solve practical testing problems through the use of item response theory (IRT). The topics, organization, and presentation are those used in a 4-week seminar held each summer for the past several years. The material is organized to facilitate understanding; all related…

A flexilevel test is found to be inferior to a peaked conventional test for measuring examinees in the middle of the ability range, superior for examinees at the extremes. Throughout the entire range of ability, a flexilevel test is much superior to any conventional test that attempts to provide accurate measurement at both extremes. See also ED…

Under given conditions, conventional testing and computer-generated repeatable testing (CGRT) are equally effective for estimating examinee ability; CGRT is more effective for estimating the mean ability level of a group and less effective for estimating ability differences among individuals. These conclusion are drawn from domain-referenced test…

Omitted items cannot properly be treated as wrong when estimating ability and item parameters. A convenient method for utilizing the information provided by omissions is presented. Theoretical and empirical justifications are presented for the estimates obtained by the new method. (Author)

Some stochastic approximation procedures are considered in relation to the problem of choosing a sequence of test questions to accurately estimate a given examinee's standing on a psychological dimension. Illustrations are given evaluating certain procedures in a specific context. (Author/CK)

This study compares the contribution to measurement accuracy of the verbal score of each of four verbal item types included in the Graduate Record Examinations (GRE) General Test. Comparisons are based on item response theory, a methodology that allows the researcher to look at the accuracy of individual points on the score scale. This methodology…