Detection of Differential Item Functioning in Multiple Groups

Abstract

Detection of differential item functioning (DIF) is most often done between two groups of examinees under item response theory. It is sometimes important, however, to determine whether DIF is present in more than two groups. In this article we present a method for detection of DIF in multiple groups. The method is closely related to Lard's chi‐square for comparing vectors of item parameters estimated in two groups. An example using real data is provided.