Digital Module 29: Multidimensional Item Response Theory Equating

In this digital ITEMS module, Dr. Stella Kim provides an overview of multidimensional item response theory (MIRT) equating. Traditional unidimensional item response theory (IRT) equating methods impose the sometimes untenable restriction on data that only a single ability is assessed. This module discusses potential sources of multidimensionality and presents potential consequences of multidimensionality on equating. To remedy these effects, MIRT equating can be used as a viable alternative to traditional methods of IRT equating. In conducting MIRT equating, the choice of an appropriate MIRT model is necessary, and thus the module describes several existing MIRT models and illustrates each using hypothetical examples. After a brief description of MIRT models, an extensive review of the current literature is presented to identify gaps in the literature on MIRT equating. Then, the steps for conducting MIRT observed-score equating are described. Finally, the module discusses practical considerations in applying MIRT equating to testing practices and suggests potential areas of research for future studies.