An overview of statistical methods to assess differential item functioning and differential test functioning

This talk broadly focuses on the identification of differential item functioning (DIF) and differential test functioning (DTF). After a short introduction of the key concepts, most-known methods to detect DIF and DTF with dichotomously or polytomously scored items, and between two or more than two groups, are presented. Both parametric (i.e. IRT) and nonparametric (i.e. score-based) methods are described in a non-technical way. Several potential applications to PISA surveys are discussed.