Dif Detection and Description: Mantel‐haenszel and Standardization1,2

ABSTRACT At the Educational Testing Service, the Mantel‐Haenszel procedure is used for differential item functioning (DIF) detection and the standardization procedure is used to describe DIF. This report describes these procedures. First, an important distinction is made between DIF and Impact, pointing the need to compare the comparable. Then, these two contingency table DIF procedures are described in some detail, first in terms of their own origins as DIF procedures, and then from a common framework that points out similarities and differences. The relationship between the Mantel‐Haenszel procedure and IRT models in general and the Rasch model, in particular, is discussed. The utility of the standardization approach for assessing differential distractor functioning is described. Several issues in applied DIF analyses are discussed including inclusion of the studied item in the matching variable, and refinement of the matching variable. Future research topics dealing with the matching variable, the studied variable and the group variable are also discussed.