International large-scale assessments of achievement often have a large degree of differential item functioning (DIF) between countries, which can threaten score equivalence and reduce the validity of inferences based on comparisons of group performances. It is important to understand potential sources of DIF to improve the validity of future…

In international achievement studies, questionnaires typically ask about the presence of particular household assets in students' homes. Responses to the assets questions are used to compute a total score, which is intended to represent household wealth in models of test performance. This study uses item analysis and confirmatory factor analysis…