Michael Eid, PhD, is Professor of Methods and Evaluation at the Free University of Berlin in Germany. His research focuses on measurement theory, in particular on the development of psychometric models for longitudinal and multimethod research. Since the early 2000s, he has been contributing to the development of structural equation models for analyzing multirater data for different types of raters and research designs. His more applied research contributions are in the areas of subjective well-being, mood regulation, and health psychology.