MIMIC models for uniform and non-uniform DIF as moderated mediation models
In this note we describe how multiple indicators multiple cause (MIMIC) models for studying uniform and non-uniform differential item functioning (DIF) can be conceptualized as mediation and moderated mediation models. Conceptualizing DIF within the context of a moderated mediation model helps us understand DIF as the effect of some variable on our measurements which is not accounted for by the latent variable of interest. In addition, this allows us to apply useful concepts and ideas from the mediation and moderation literature: (1) improving our understanding of uniform and non-uniform DIF as direct effects and interactions, (2) understanding the implication of indirect effects in DIF analysis, (3) clarifying the interpretation of the “uniform DIF parameter” in the presence of non-uniform DIF, and (4) probing interactions and using the concept of “conditional effects” to better understand the patterns of DIF across the range of the latent variable.