Coefficient alpha reliability persists as the most common reliability coefficient reported in research. The assumptions for its use are, however, not well-understood. The current paper challenges the commonly used expressions of coefficient alpha and argues that while these expressions are correct when estimating reliability for summed scores,…

In this digital ITEMS module, Dr. Jeffrey Harring and Ms. Tessa Johnson introduce the linear mixed effects (LME) model as a flexible general framework for simultaneously modeling continuous repeated measures data with a scientifically defensible function that adequately summarizes both individual change as well as the average response. The module…

The main points of Sijtsma and Green and Yang in Educational Measurement: Issues and Practice (34, 4) are that reliability, internal consistency, and unidimensionality are distinct and that Cronbach's alpha may be problematic. Neither of these assertions are at odds with Davenport, Davison, Liou, and Love in the same issue. However, many authors…

The purpose of this article was to present a synthesis of the peer-reviewed differential bundle functioning (DBF) research that has been conducted to date. A total of 16 studies were synthesized according to the following characteristics: tests used and learner groups, organizing principles used for developing bundles, DBF detection methods used,…

The goal of this study was to investigate the usefulness of person-fit analysis in validating student score inferences in a cognitive diagnostic assessment. In this study, a two-stage procedure was used to evaluate person fit for a diagnostic test in the domain of statistical hypothesis testing. In the first stage, the person-fit statistic, the…

Test items undergo multiple iterations of review before states and vendors deem them acceptable to be placed in a live statewide assessment. This article reviews three approaches that can add validity evidence to states' item review processes. The first process is a structured sensitivity review process that focuses on universal design…

This module prepares the reader to use statistical procedures to detect differentially functioning test items. The Mantel-Haenszel statistic, logistic regression, the SIBTEST procedure, the Standardization procedure, and various item response theory-based procedures are presented. Theoretical frameworks, strengths and weaknesses, and…

In this paper I describe and illustrate the Roussos-Stout (1996) multidimensionality-based DIF analysis paradigm, with emphasis on its implication for the selection of a matching and studied subtest for DIF analyses. Standard DIF practice encourages an exploratory search for matching subtest items based on purely statistical criteria, such as a…