Contributed paper A Bayesian Approach for Fitting a Random Effect Differential Item Functioning Across Group Units

This study proposed a multilevel logistic regression model to evaluate variation of differential item functioning (DIF). The model accounts for the three level nested structure of the data and combines results of logistic regression analyses to investigate the variation of DIF across level-3 units. A simulation study is presented to assess the adequacy of the proposed model. The parameters of the proposed model were estimated by using a Bayesian approach implemented by the WinBUGS 1.4