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.…

This technical report and user's guide is designed to provide researchers with an overview of the design and implementation of the 2009 Program for International Student Assessment (PISA), as well as with information on how to access the PISA 2009 data. This information is meant to supplement that presented in Organization for Economic Cooperation…

Reports that no significant difference in reliability appeared between a heterogeneous and a homogeneous form of the same general science matching-item test administered to 316 sixth-grade students but that scores on the heterogeneous form of the test were higher, independent of the examinee's sex or intelligence. (SB)