IDENTIFICATION OF NONUNIFORM DIFFERENTIAL ITEM FUNCTIONING USING A VARIATION OF THE MANTEL-HAENSZEL PROCEDURE

The Mantel-Haenszel (MH) procedure has become one of the most popular procedures for detecting differential item functioning (DIF). One of t he most troublesome criticisms of this procedure is that whereas detec tion rates for uniform DIF are very good, the procedure is not sensiti ve to nonuniform DIF. In this study, examinee responses were generated to simulate both uniform and nonuniform DIF. A standard MH procedure was used first. Then, examinees were split into two samples by breakin g the full sample at approximately the middle of the test score distri bution. The tests were then reanalyzed, first with the low-performing sample and then with the high-performing sample. This variation improv ed detection rates of nonuniform DIF considerably over the total sampl e procedure without increasing the Type I error rate. Items with the l argest differences in discrimination and difficulty parameters were mo st likely to be identified.