The Impact of Differential Item Functioning on General Factor Mean Difference Estimation for Bifactor Ordinal Data

• In Event: Methods for Multilevel, Categorical, and Multidimensional Data

Abstract

A simulation study was conducted to explore the impact of DIF on general factor difference estimation for bifactor ordinal data. The estimation bias resulting from ignoring DIF mainly depended on the type of parameters with DIF. When ignoring DIF in threshold parameters, very substantial estimation bias was produced and the Type I error rates (powers) were inflated for many conditions. In contrast, when ignoring DIF in general factor loadings, a little estimation bias was produced; when ignoring DIF in specific factor loadings, almost no estimation bias was produced. All Type I error rates fell in the required limits when DIF was present in factor loadings, and powers were not influenced by ignoring DIF in factor loadings.

Authors

• Yixing Liu, Arizona State University

• Marilyn S. Thompson, Arizona State University