Multiple-Group Noncompensatory Differential Item Functioning in Raju's Differential Functioning of Items and Tests

摘要

Raju, van der Linden, and Fleer (1995) introduced a framework for differential functioning of items and tests (DFIT) for unidimensional dichotomous models. Since then, DFIT has been shown to be a quite versatile framework as it can handle polytomous as well as multidimensional models both at the item and test levels. However, DFIT is still limited by the two-group comparison (reference vs. focal group). In real testing situations, it is quite common that a practitioner or researcher may want to compare more than two groups simultaneously. Ethnicity, for example, may have three or more categories. This current study extends the two-group noncompensatory differential item functioning index (NCDIF) in DFIT to multiple-group NCDIF. The significance test developed for the two-group NCDIF and effect size were utilized in the multiple-group cases. The effectiveness of this new approach is demonstrated in a simulation study where various degrees and types of DIF are embedded.