Methods to generate random correlation matrices have been proposed in the literature, but very few instances exist where these correlation matrices are structured or where the statistical properties of the algorithms are known. By relying on the tetrad relation discovered by Spearman and the properties of the beta distribution, an algorithm is…

There is such doubt in research practice about the reliability of difference scores that granting agencies, journal editors, reviewers, and committees of graduate students' theses have been known to deplore their use. This most maligned index can be used in studies of change, growth, or perhaps discrepancy between two measures taken on the same…

This paper provides a conceptual, empirical, and practical guide for estimating ordinal reliability coefficients for ordinal item response data (also referred to as Likert, Likert-type, ordered categorical, or rating scale item responses). Conventionally, reliability coefficients, such as Cronbach's alpha, are calculated using a Pearson…

Type I error rates in multiple regression, and hence the chance for false positive research findings, can be drastically inflated when multiple regression models are used to analyze data that contain random measurement error. This article shows the potential for inflated Type I error rates in commonly encountered scenarios and provides new…

In a recent Monte Carlo simulation study, Liu and Zumbo showed that outliers can severely inflate the estimates of Cronbach's coefficient alpha for continuous item response data--visual analogue response format. Little, however, is known about the effect of outliers for ordinal item response data--also commonly referred to as Likert, Likert-type,…

In this study, the Canadian English and French versions of the Problem-Solving Measure of the Programme for International Student Assessment 2003 were examined to investigate their degree of measurement comparability at the item- and test-levels. Three methods of differential item functioning (DIF) were compared: parametric and nonparametric item…

Office discipline referrals (ODRs) are commonly used by school teams implementing schoolwide positive behavior support to indicate individual student need for additional behavior support. However, little is known about the technical adequacy of ODRs when used in this manner. In this study, the authors assessed (a) the concurrent validity of number…

The impact of outliers on Cronbach's coefficient [alpha] has not been documented in the psychometric or statistical literature. This is an important gap because coefficient [alpha] is the most widely used measurement statistic in all of the social, educational, and health sciences. The impact of outliers on coefficient [alpha] is investigated for…

Presents a model of tests and measurement that identifies test scores with Hilbert space vectors and true and error components of scores with linear operators. This geometric point of view brings to light relations among elementary concepts in test theory, including reliability, validity, and parallel tests. (Author/SLD)

Agonias is an idiom of distress for Portuguese community members. Although this phenomenon was recently introduced in the mental health literature, a measure for it was not available. The Agonias Scale was introduced in this article and the psychometric properties are reported. The scale was found to have strong psychometric properties of…