Gregory R. Hancock is Professor and Department Chair in the Department of Measurement, Statistics and Evaluation at the University of Maryland, College Park, and Director of the Center for Integrated Latent Variable Research (CILVR).  His research has appeared in such journals as Psychometrika, Multivariate Behavioral Research, Structural Equation Modeling: A Multidisciplinary Journal, Psychological Bulletin, British Journal of Mathematical and Statistical Psychology, Journal of Educational and Behavioral Statistics, Educational and Psychological Measurement, Review of Educational Research, and Communications in Statistics: Simulation and Computation.  He also co-edited with Ralph Mueller the volume Structural Equation Modeling: A Second Course, and with Karen M. Samuelsen the volume Advances in Latent Variable Mixture Models.  He is past chair of the SEM special interest group of the American Educational Research Association, serves on the editorial board of a number of journals including Structural Equation Modeling: A Multidisciplinary Journal, and has taught dozens of SEM workshops in the United States and abroad. Dr. Hancock holds a Ph.D. from the University of Washington.  He can be reached via email at: ghancock@umd.edu.

Ralph O. Mueller is Professor of Educational Research and Public Policy and Public Administration and former Chair of the Department of Educational Leadership at The George Washington University, Washington, DC where he teaches the full range of quantitative research methods courses.  He is the author of Basic Principles of Structural Equation Modeling: An Introduction to LISREL and EQS and co-edited with Greg Hancock Structural Equation Modeling: A Second Course.  His work deals primarily with the pedagogy and proper application of structural equation modeling (SEM) in the social and behavioral sciences.  Dr. Mueller conducts regular professional development seminars on SEM for the American Educational Research Association and is past chair of its special interest group on SEM.  He serves on the editorial boards of Educational and Psychological Measurement and Measurement and Evaluation in Counseling and Development, was a charter board member of Structural Equation Modeling: A Multidisciplinary Journal, and has been teaching SEM workshops for over 20 years.  Dr. Mueller holds a Ph.D. in educational research and evaluation from Virginia Tech.  He can be reached via email at: rmueller@gwu.edu.