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...

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...

In this paper, a method for studying DIF is demonstrated that can used with either dichotomous or polytomous items. The method is shown to be valid for data that follow a partial credit IRT model. It is also shown that logistic regression gives results equivalent to those of the proposed method....

Differential item functioning (DIF) occurs when persons with equal ability who belong to different groups have a different probability to correctly solve an item of a certain test. As the occurrence of DIF is considered a serious problem when using tests for personnel selection, many procedures...