Robert H. Friis, PhD, earned his doctorate from Columbia University and completed a postdoctoral fellowship in social epidemiology at the Institute for Social Research, University of Michigan, Ann Arbor. He received his Bachelor of Arts degree in psychology from the University of California at Berkeley. He has had more than three decades of teaching and research experience in epidemiology. Formerly, he was Assistant Professor of Epidemiology at the Columbia University School of Public Health, Assistant Professor of Pediatrics and Community Health at Albert Einstein College of Medicine, and Assistant Professor of Health Science at Brooklyn College of the City University of New York. Subsequently, he was Director of the Field Epidemiology Unit at the Orange County (California) Public Health Department. Later he became a faculty member in the Department of Medicine, Department of Neurology, and the School of Social Ecology at the University of California, Irvine. Currently, he is Professor and Chair of the Health Science Department at California State University, Long Beach, where he has taught introductory epidemiology and biostatistics. He has been involved in numerous epidemiologic research projects and has drafted more than 50 professional and scientific articles. He is a member of the Society for Epidemiologic Research and the epidemiology section of the American Public Health Association. He is also Clinical Professor of Community and Environmental Medicine at the University of California, Irvine. See the author as the “Expert” in Epidemiology in a short video on “Video Jug.”

Thomas A. Sellers, PhD, MPH, earned his doctorate in epidemiology from Tulane University and has postdoctoral training in genetic epidemiology. He received his Bachelors of Science degree in Community Nutrition from University of California at Davis. For nine years he was on the faculty at the University of Minnesota, where he taught the Introduction to Epidemiology course for non-majors. He is currently Associate Center Director, H. Lee Moffitt Cancer Center and Research Institute, University of South Florida. Dr. Sellers has drafted more than 150 articles, letters, and book chapters with a primary focus on the etiology of common cancers. He has maintained continuous funding for his research from the National Cancer Institute for almost 15 years. The range and diversity of his experience is evident in many of the study examples presented in the text.