A new formula, expressing relative efficiency solely in terms of the standard errors of measurement and the frequency of distributions of true scores, is developed for the relative efficiency of two tests measuring the same trait. Subtests from the Scholastic Aptitude Test provide a numerical illustration. (Author/RC)

A statistical test for cheating is developed. The case of a single examinee who has taken parallel forms of the same selection test on three occasions, obtaining scores x, y, z, is used to illustrate the development. It is assumed that each score is normally distributed with the same known variance, that is, the variance of the errors of…

A numerical procedure is outlined for obtaining an interval estimate of the regression of true score or observed score, utilizing only the frequency distribution of observed scores. The procedure assumes that the conditional distribution of observed scores for fixed true scores is binomial. Several illustrations are given. (Author/HG)

A new formula is developed for the relative efficiency of two tests measuring the same trait. The formula expresses relative efficiency solely in terms of the standard errors of measurement and, surprisingly, the frequency distributions of true scores. Approximate methods for estimating relative efficiency may make this function routinely…

A numerical procedure is outlined for obtaining an interval estimate of true score. The procedure is applied to several sets of test data. (Author)

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)

Two methods of 'equating' tests using item response theory (IRT) are compared, one using true scores, the other using the estimated distribution of observed scores. On the data studied, they yield almost indistinguishable results. This is a reassuring result for users of IRT equating methods. (Author)

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)

Four methods are outlined for estimating or approximating from a single test administration the standard error of measurement of number-right test score at specified ability levels or cutting scores. The methods are illustrated and compared on one set of real test data. (Author)

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)