A Synthesis of 15 Years of Research on DIF in Language Testing: Methodological Advances, Challenges, and Recommendations

This article reviews research on differential item functioning (DIF) in language testing conducted primarily between 1990 and 2005 with an eye toward providing methodological guidelines for developing, conducting, and disseminating research in this area. The article contains a synthesis of 27 studies with respect to five essential sets of characteristics: (a) features of the tests utilized, (b) features of the learner groups employed, (c) features of the DIF detection methods applied, (d) features of the reporting of DIF effects, and (e) features of the explanations for and consequences drawn from DIF results. Methodological recommendations for improving the conceptualization and the reporting of DIF research in the field of language testing is provided with an eye toward developing statistical meta-analyses that aid practitioners in interpreting the relevance of DIF results more precisely.