Bifactor Multidimensional Item Response Theory Observed-Score Equating for Mixed-Format Tests

• In Event: Factors Impacting Equating Results

Abstract

The main purposes of this study were to develop bi-factor multidimensional item response theory (BF-MIRT) observed-score equating procedures for mixed-format tests and to investigate relative appropriateness of the proposed procedures. Data for this study were from the College Board Advanced Placement (AP) examinations and three data sets were formulated: matched samples, pseudo forms, and simulated data sets. Very minor within-format residual dependence in mixed-format tests was found after controlling for the influence of the primary general factor. Either the unidimensional IRT (UIRT) or BF-MIRT observed-score equating method can be considered for practical equating. The BF-MIRT equating method would produce better equating results for mixed-format tests compared to the UIRT method with non-negligible multidimensionality.

Authors

• Guemin Lee, Yonsei University

• Won-Chan Lee, University of Iowa