care; and the construction and evaluation of simulation models with a special focus on characterization and quantification of sources of uncertainty. He is the author of numerous articles on these topics and, with others, of the book Public Policy and Statistics: Case Studies from RAND. For the National Academies Committee on National Statistics, he has served as a committee member for the Panel Study of Data and Methods for Measuring the Effects of Changes in Social Welfare Programs and the Panel to Review Research and Development Statistics at the National Science Foundation.
DENISE C. GOTTFREDSON is a professor at the University of Maryland Department of Criminal Justice and Criminology. Gottfredson’s research interests include delinquency and delinquency prevention, and particularly the effects of school environments on youth behavior. Much of Gottfredson’s career has been devoted to developing effective collaborations between researchers and practitioners. She directs a project that provides research expertise to the Maryland Governor’s Office of Crime Control and Prevention in its efforts to promote effective prevention practices in Maryland. She has recently completed randomized experiments to test the effectiveness of the Baltimore City Drug Treatment Court and the Strengthening Families Program in Washington DC. She is currently directing a randomized trial of the effects of after school programs on the development of problem behavior. She received a Ph.D. in Social Relations from the Johns Hopkins University, where she specialized in Sociology of Education.
JOHN V. PEPPER is associate professor of economics at the University of Virginia. His current work reflects his wide range of interests in social program evaluation, applied econometrics, and public economics. His current work examines such subjects as disability status, teenage childbearing, welfare system rules, and drugs and crime. He is an author of numerous published papers, conference presentations and edited books including several National Research Council reports—Measurement Problems in Criminal Justice Research (2003, with Carol Petrie), Informing America’s Policy on Illegal Drugs: What We Don’t Know Keeps Hurting Us (2001, with Charles Manski and Carol Petrie), Assessment of Two Cost-Effectiveness Studies on Cocaine Control Policy (1999, with Charles Manski and Yonette Thomas), and Firearms and Violence: A Critical Review (2005, with Charles Wellford and Carol Petrie). Professor Pepper received his Ph.D. in economics from the University of Wisconsin-Madison.
DAVID WEISBURD is the Walter E. Mayer Professor of Law and Criminal Justice at Hebrew University Law School in Jerusalem and professor