Assessing differential statement functioning in multidimensional forced-choice items

Ipsative tests with multidimensional forced-choice (MFC) items are popular inpersonality and career interests measurement in which respondents are ’forced’ to choosea statement from a pair of statements or to rank a set of statements that are designed to measure different dimensions. Recently, a new item response theory (IRT) model has been developed for such tests. In the new model,each statement within a MFC item has a utility parameter for all persons. In reality, a statement may have different utilities for different groups of persons, which is referred to as differential statement functioning (DSF). In this study, we adapted an IRT-based method to the DSF assessment. Simulation studies showed that the adapted method maintained good control of Type I error rates and yielded high power rates. An ipsative career interests test with MFC items was assessed for the DSF between genders.