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...

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...