A CONFIRMATORY SURVEY OF DIFFERENTIAL ITEM FUNCTIONING
Authors: Hosseini Ameneh
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For the development of comparable tests in international studies it is essential to examine Differential Item Functioning (DIF) by different demographic groups, in particular cultural and language groups. For the selection of test items it is important to analyze the extent to which items function differently across the sub-groups of students. For the past several years, interest has been demonstrated in the study of differential item functioning (DIF). DIF is investigated whenever one wants to identify items on which two groups of examinees, matched on a mea sure of an appropriate variable, do not perform the same. Motivation for studying DIF could stem from psychometric considerations or from broader issues having to do with pedagogical, social, or psychological questions. The purpose of this study is to help ensure that strategies for differential item functioning (DIF) detection for students with disabilities are appropriate and lead to meaningful results. We surveyed existing DIF studies for students with disabilities and describe them in terms of study design, statistical approach, sample characteristics, and DIF results. Based on descriptive and graphical summaries of previous DIF studies, we make recommendations for future studies of DIF for students with disabilities.