THE STANDARDIZATION APPROACH TO ASSESSING COMPREHENSIVE DIFFERENTIAL ITEM FUNCTIONING

The standardization approach to comprehensive differential item functioning (Cdif) is described and contrasted with the log-linear approach to differential distractor functioning explicated by Green, Crone, and Folk (1989) and with the IRT-based approach to differential alternative functioning explicated by Thissen, Steinberg and Wainer (1992). This descriptive approach is used routinely as an adjunct to Mantel-Haenszel differential item functioning (DIF) detection (Dorans & Holland, 1992) in many operational testing programs at the Educational Testing Service. Data from an edition of the SAT are used to illustrate how the standardization approach to Cdif could be used to uncover differential speededness. Speculations about the sources of differential speededness for Black examinees and Hispanic examinees are offered, and some implications of the existence of differential speededness for DIF detection are mentioned.