Multilevel Mixed-Measurement IRT Analysis: An Explication and Application to Self-Reported Emotions Across the World

Dimensional approaches assume that all individuals within hierarchical units (e.g., organizations or countries) share the same measurement model. However, such models are less applicable when researchers are interested in obtaining classes of individuals who share the same measurement model across hierarchical units and to obtain hierarchical latent classes (LCs). The authors present the multilevel mixed-measurement item response theory (MMM-IRT) model as an alternative. This model yields classes of individuals with a common measurement model that spans across hierarchical units. In addition, hierarchical units are classified together to the extent that they share similar proportions of individual-level classes. The authors illustrate the MMM-IRT model with data on self-reported emotions from 121,740 individuals across 116 countries where four individual classes and five country classes were found. Theoretical and methodological implications concerning cross-cultural, multilevel, and measurement equivalence research are discussed.