Test equating in the presence of DIF items.

This paper proposes a multilevel measurement model that controls for DIF effects in test equating. The accuracy and stability of item and ability parameter estimates under the proposed multilevel measurement model were examined using randomly simulated data. Estimates from the proposed model were compared with those resulting from two multiple-group concurrent equating designs, including 1) a design that replaced DIF-items with items with no DIF; and 2) a design that retained DIF items with no attempt to control for DIF. In most of the investigated conditions, the results indicated that the proposed multilevel measurement model performed better than the two comparison models.