Detection of Differential Item Functioning Using Mantel-Haenszel, Standardization Proportion and BILOG-MG Procedures
Differential item functioning (DIF) is a procedure to identify whether an item favours a particular group of respondents once they are matched on respective ability levels. There are numerous procedures reported in the literature to detect DIF, but the Mantel-Haenszel (MH), Standardized Proportion Difference (SPD), and BILOG-MG are frequently used to ensure the fairness of assessments. The aim of the present study was to compare procedural characteristics using empirical data. We found Mantel-Haenszel and standardized proportion difference provide comparable results while BILOG-MG has flagged a large number of items, but the magnitude of DIF was trivial from a test development perspective. The results also showed Mantel-Haenszel and standardized proportion difference index provide the effect size measure of DIF, which facilitates for further necessary actions, especially for item writers and practitioners.