Extensions of Mantel-Haenszel for Multilevel DIF Detection

Multilevel data structures are ubiquitous in the assessment of differential item functioning (DIF), particularly in large-scale testing programs. There are a handful of DIF procures for researchers to select from that appropriately account for multilevel data structures. However, little, if any, work has been completed to extend a popular DIF method to this case. Thus, the primary goal of this study was to introduce and investigate the effectiveness of several new options for DIF assessment in the presence of multilevel data with the Mantel-Haenszel (MH) procedure, a popular, flexible, and effective tool for DIF detection. The performance of these new methods was compared with the standard MH technique through a simulation study, where data were simulated in a multilevel framework, corresponding to examinees nested in schools, for example. The standard MH test for DIF detection was employed, along with several multilevel extensions of MH. Results demonstrated that these multilevel tests proved to be preferable to standard MH in a wide variety of cases where multilevel data were present, particularly when the intraclass correlation was relatively large. Implications of this study for practice and future research are discussed.