Michael C. Edwards is an Associate Professor in the Quantitative Area of the Department of Psychology at The Ohio State University. He received his PhD in 2005 from the L.L. Thurstone Psychometric Laboratory at the University of North Carolina at Chapel Hill. His research focuses on measurement issues in the social sciences with specific topics including multidimensional item response theory, computerized adaptive testing, local dependence, and measurement invariance. Robert C. MacCallum is Professor Emeritus of Psychology at both the University of North Carolina at Chapel Hill and Ohio State University. He received his graduate training at the University of Illinois and then spent 28 years on the faculty in the Quantitative Psychology program at Ohio State University, moving to UNC in 2003. His research interests focus on methods for analysis and modeling of correlational and longitudinal data, including factor analysis, structural equation modeling, and latent curve models. Within these areas he has worked on various issues including model estimation and evaluation, power analysis for testing models, and the nature and management of sources of error in modeling. His current interests involve the study of uncertainty inherent in results of statistical models. He is former Director of the L. L. Thurstone Psychometric Laboratory at UNC, and former president of the Society for Multivariate Experimental Psychology. In 2011 he received the Samuel J. Messick Award for distinguished scientific contributions from Division 5 of the American Psychological Association.