Different Approaches to Differential Item Functioning in Health Applications

An integrated approach to the examination of measurement equivalence, invariance, and DIF is necessary for measurement in an increasingly multi-ethnic society. Ideally, qualitative analyses should be performed in an iterative fashion to inform about findings of DIF. However, if an already-developed measure is being evaluated, then the steps might be to focus first on dimensional invariance using factor analytic methods, followed by DIF analyses examining both significance and magnitude of DIF, accompanied by formal tests of the impact of DIF. The DIF analytic method selected in the second step might be determined based on the findings summarized in the table presented within this paper.