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…

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…

This study examined the validity of test accommodation in third-eighth graders using differential item functioning (DIF) and mixture IRT models. Two data sets were used for these analyses. With the first data set (N = 51,591) we examined whether item type (i.e., story, explanation, straightforward) or item features were associated with item…

Potential benefits of using item response theory in test construction are evaluated using the experience and evidence accumulated during nine years of using a three-parameter model in the development of major achievement batteries. Topics addressed include error of measurement, test equating, item bias, and item difficulty. (TJH)

An experiment is reported in which 225 high school students were asked to choose among several multiple-choice items but then were required to answer them all. It is concluded that allowing choice while having fair tests is only possible when choice is irrelevant in terms of difficulty. (SLD)

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)