Reporting effect size plays an integral role in educational and psychological research and is required by many journals. Certainly, the best-known measure of effect size is Cohen's d, which represents a substantial improvement over using p values. But Cohen's d is known to suffer from some fundamental concerns. The author's goal was to illustrate…

It is known that nonnormality, a heteroscedastic error term, or a nonlinear association can create serious practical problems when using the conventional analysis of covariance (ANCOVA) method. This article describes a simple ANCOVA method that allows heteroscedasticity, nonnormality, nonlinearity, and multiple covariates. When standard…

Using a new coefficient, a rescaling of the Bayes risk is examined and a modification of this coefficient is described which yields an index that always has a value between zero and one. (Author/MH)

A new method of measuring item bias based on the latent class model proposed by the author is suggested. A test for item bias is also suggested that is based on standard asymptotic results. (Author/DWH)

For two random variables, X and Y, let D = X - Y, and let theta[subscript x], theta[subscript y], and theta[subscript d] be the corresponding medians. It is known that the Wilcoxon-Mann-Whitney test and its modern extensions do not test H[subscript o] : theta[subscript x] = theta[subscript y], but rather, they test H[subscript o] : theta[subscript…

Reviews new techniques for dealing with the problem that slight departures from normality can substantially lower power when means are compared and that a popular measure of effect size can be misleading. Contemporary ways of comparing groups can reveal important differences that are missed by conventional methods based on means. (SLD)

A procedure for determining the reliability of an examinee knowing k out of n possible multiple choice items given his or her performance on those items is presented. Also, a scoring procedure for determining which items an examinee knows is presented. (Author/JKS)

False-positive and false-negative decisions are the two possible errors committed with a mastery test; yet the estimation of the likelihood of committing these errors has not been investigated. Two methods of this type of estimation are presented and discussed. (Author/JKS)

This document presents a series of five papers describing issues in educational measurement. "A Simple Model for Diagnostic Testing When There Are Several Types of Misinformation" directly addresses the diagnostic issue. It describes a simple latent trait model for testing, examines use of erroneous algorithms, and illustrates the…

A closed sequential procedure for estimating true score is proposed for use with answer-until-correct tests. The accuracy of determining true score is the same as in conventional sequential solutions, but the possibility of using an unnecessarily large number of items is eliminated. (Author/CM)