Differential item functioning (DIF) can lead to an unfair advantage or disadvantage for certain subgroups in educational and psychological testing. Therefore, a variety of statistical methods has been suggested for detecting DIF in the Rasch model. Most of these methods are designed for the...

Measurement invariance is a fundamental assumption in item response theory models, where the relationship between a latent construct (ability) and observed item responses is of interest. Violation of this assumption would render the scale misinterpreted or cause systematic bias against certain...

For detecting differential item functioning (DIF) between two groups of test takers, their item parameters need to be aligned in some way. Typically this is done by means of choosing a small number of so called anchor items. Here we propose an alternative strategy: the selection of an anchor...