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. Christian Geiser, PhD, is a former professor of quantitative psychology. He currently works as an instructor and statistical consultant with QuantFish. His areas of expertise are in structural equation modeling, measurement, longitudinal data analysis, latent class modeling, and multitrait–multimethod analysis. Tobias Koch, PhD, is Professor of Psychological Methods at the Friedrich-Schiller-Universität Jena in Germany. His research focuses on measurement theory and psychometrics, structural equation modeling, longitudinal data analysis, multilevel analysis, Bayesian analysis, and multitrait–multimethod analysis.