This article illustrates the use of an explanatory item response modeling (EIRM) approach in the context of measuring group differences in science achievement. The distinction between item response models and EIRMs, recently elaborated by De Boeck and Wilson (2004), is presented within the statistical framework of generalized linear mixed models.…

Describes studies involving students sponsored by A Better Chance, Inc. (ABC), a nonprofit search and referral service that identifies and places talented minority inner-city children. Results indicate that standardized tests do not necessarily predict ABC student success, and that ABC students can be productively directed toward mathematics and…