Differential Item Functioning: Current Issues

Abstract

This study describes current issues of differential item functioning (DIF) used by psychometricians and test specialists to identify item fairness across members of different subgroups such as males and females. First, the definition of DIF was discussed, centering on Simpson's paradox and two different types of DIF: uniform DIF and non-uniform DIF. Then, three commonly used DIF detection techniques - the MantelHaenszel method, confirmatory factor analysis (CFA), and the likelihood ratio (LR) test - were introduced. Third, the relation of DIF to differential test functioning (DTF) was explored with the generation of three research hypotheses based on current empirical studies. Finally, this study was concluded with future research inquiries to be answered.