A Generalized Logistic Regression Procedure to Detect Differential Item Functioning Among Multiple Groups

Abstract

We present an extension of the logistic regression procedure to identify dichotomous differential item functioning (DIF) in the presence of more than two groups of respondents. Starting from the usual framework of a single focal group, we propose a general approach to estimate the item response functions in each group and to test for the presence of uniform DIF, nonuniform DIF, or both. This generalized procedure is compared to other existing DIF methods for multiple groups with a real data set on language skill assessment. Emphasis is put on the flexibility, completeness, and computational easiness of the generalized method.

Keywords:

• differential item functioning
• logistic regression
• multiple groups

Acknowledgments

The authors wish to thank Prof. Stephen G. Sireci, editor, Prof. Rob R. Meijer, co-editor, and two anonymous reviewers for their helpful comments. This research was funded by a grant “Chargé de recherches” of the National Funds for Scientific Research (FNRS), Belgium, the Research Funds of the K. U. Leuven, and a grant from the Social Sciences Research Council of Canada (SSRC).