When there are no personal consequences associated with test performance for examinees, rapid guessing (RG) is a concern and can differ between subgroups. To date, the impact of differential RG on item-level measurement invariance has received minimal attention. To that end, a simulation study was conducted to examine the robustness of the…

The usefulness of item response theory (IRT) models depends, in large part, on the accuracy of item and person parameter estimates. For the standard 3 parameter logistic model, for example, these parameters include the item parameters of difficulty, discrimination, and pseudo-chance, as well as the person ability parameter. Several factors impact…

In this article, we discuss and illustrate two centering and anchoring options available in differential item functioning (DIF) detection studies based on the hierarchical generalized linear and generalized linear mixed modeling frameworks. We compared and contrasted the assumptions of the two options, and examined the properties of their DIF…

Testlets, or groups of related items, are commonly included in educational assessments due to their many logistical and conceptual advantages. Despite their advantages, testlets introduce complications into the theory and practice of educational measurement. Responses to items within a testlet tend to be correlated even after controlling for…

Three types of effects sizes for DIF are described in this exposition: log of the odds-ratio (differences in log-odds), differences in probability-correct, and proportion of variance accounted for. Using these indices involves conceptualizing the degree of DIF in different ways. This integrative review discusses how these measures are impacted in…

One-parameter and three-parameter item response theory (IRT) model estimates were compared with estimates obtained from two modified one-parameter models that incorporated a constant nonzero guessing parameter. Using small-sample simulation data (50, 100, and 200 simulated examinees), modified 1-parameter models were most effective in estimating…

Compared easy and difficult versions of self-adapted tests (SAT) and computerized adapted tests. No significant differences were found among the tests for estimated ability or posttest state anxiety in studies with 187 Spanish high school students, although other significant differences were found. Discusses implications for interpreting test…

Four simulated mathematical and verbal test forms were produced by test assembly procedures proposed in legislative bills in California and New York in 1986 to minimize differences between majority and minority scores. Item response theory analyses of data for about 22,000 black and 28,000 White high-school students were conducted. (SLD)