At the outset, I wish to thank the members of the Panel to Evaluate Microsimulation Models for Social Welfare Programs for their generous contributions of time and expert knowledge. Several panel members served ably as chairs of working groups on broad issues. Other members participated extensively in the analysis of the panel's Transfer Income Model 2 (TRIM2) validation experiment. Still others contributed papers (in Volume II) or sets of notes on specific topics that greatly helped in preparation of the panel's report. Overall this was an exceptionally hard-working panel that strove unstintingly to grapple with a complex set of problems covering a very broad terrain of policy concerns, models, and data. The members thought and worked hard to develop recommendations that would enhance the quality of policy analysis tools and thereby the quality of national debate about important social welfare issues. It has been a genuine pleasure to work with them.

Of course, anybody who has ever had contact with an effort such as this realizes that the quality of the report—to say nothing about the enjoyment and satisfaction of participating in the project—depends directly on the study director. In this case, speaking both personally and for the panel, I can say absolutely that Constance Citro was the irreplaceable input to our effort. There is little doubt that we would have produced a very different report, one not nearly so strong, if Connie had not been involved. Her substantive knowledge, her prodigious feats of writing at the word processor, and her calm, easygoing nature each contributed to the activity.

The panel is also indebted to Michael Cohen, who served as the panel's

statistical consultant throughout the project. He prepared papers reviewing statistical matching techniques for developing microsimulation databases, sample reuse techniques for estimating the variance in microsimulation model estimates, the previous literature of microsimulation model validation studies, and (in collaboration with several members of the panel) the results of the panel's TRIM2 validation experiment. Mike participated actively in the panel's deliberations and contributed materially to the quality and depth of the panel's review of model validation issues.

Christine Ross served as research associate for the panel during its first year and made extremely valuable contributions to the study. She prepared materials describing the characteristics of a number of static and dynamic microsimulation models and a background paper comparing two dynamic models. She conducted a number of interviews with agency staff on their use of microsimulation models. Overall, Chris contributed enormously to helping the panel organize its work and gather the information it needed to carry out the study.

The staffs of our sponsors, the Office of the Assistant Secretary for Planning and Evaluation (ASPE) of the U.S. Department of Health and Human Services (HHS) and the Food and Nutrition Service (FNS) of the U.S. Department of Agriculture, were extremely helpful in providing information about their use of microsimulation models for policy analysis and in making available to us the expertise and resources of their modeling contractors. We would like to thank particularly certain individuals for their assistance. Joan Turek-Brezina, Director for Technical and Computer Support for ASPE and the HHS project officer for the panel, contributed generously of her time and support in every aspect of the panel's work. Robert Dalrymple, the FNS project officer for the panel, also devoted time and energy to the project. ASPE staff, including Paul Gayer, M. Eugene Moyer, William Prosser, Reuben Snipper, and Daniel Weinberg (now with the Census Bureau), presented informative case studies of the use of microsimulation models at the panel's first meeting, as did Steven Carlson, Director of Analysis for the Office of Analysis and Evaluation in FNS. Reuben Snipper also provided detailed information about the techniques used to produce estimates for the policy debate that led to the Family Support Act of 1988.

We would also like to thank staff members of the Congressional Budget Office who shared their knowledge and insights about policy analysis techniques. In particular, we owe thanks to Janice Peskin, who provided detailed information about the procedures used to develop estimates for the Family Support Act, and to Nancy Gordon and Sandra Christensen who commented on models for health care policy issues. We would also like to thank James Cilke of the Office of Tax Analysis of the U.S. Department of the Treasury, who provided useful information on microsimulation models for tax policy.

Staff members of firms involved in microsimulation modeling provided invaluable assistance to the panel through briefings and sharing documentation

and other materials about their models with the panel. We would like to acknowledge in this regard the valuable contributions of Harold Beebout and Pat Doyle of Mathematica Policy Research, Inc., and of David Kennell and John Sheils of Lewin/ICF, Inc. We would like to thank particularly Richard Michel, Director of the Income and Benefits Policy Center at the Urban Institute, and his staff, including Sheila Zedlewski, Linda Giannarelli Paul Johnson, and Margaret Moore. Dick and Sheila not only made a number of presentations to the panel on static and dynamic models, but helped the panel design a validation experiment with TRIM2 that was a centerpiece of the panel's work, providing a wealth of information for the panel's deliberations. The experiment was ably carried out by Linda, Margaret, and Paul.

We are indebted to many other people who made presentations to the panel or prepared background papers at our behest. These include Gary Burtless of the Brookings Institution, Thomas Grannemann of the University of Colorado, and Robert Strauss of Carnegie Mellon University, each of whom prepared a paper on modeling behavioral effects of program changes; Steven Caldwell of Cornell University, who prepared a paper on techniques of aging microsimulation model databases; Deborah Chollet of Georgia State University, who prepared a paper on microsimulation models for health care policy issues; Paul Cotton of Fulcrum Technologies, Inc., and George Sadowsky of New York University, who collaborated on a paper about future computing environments for microsimulation models; Donald Fullerton of the University of Virginia, who briefed the panel on computable general equilibrium models; and Barry Bluestone of the University of Massachusetts-Amherst and John Havens and Alan Clayton-Matthews, both of Boston College, who briefed the panel on the Multi-Regional Policy Impact Simulation (MRPIS) model.

The panel also benefited greatly from a dinner meeting and discussion with congressional staff members who work with and interpret the information developed by policy analysts for the legislative debate, including William Hoagland, minority staff director for the Senate Budget Committee; Wendell Primus, chief economist of the House Ways and Means Committee; and Randall Weiss, former chief economist of the Joint Committee on Taxation and now with Deloitte and Touche.

The panel is very grateful to Eugenia Grohman, Associate Director for Reports of the Commission on Behavioral and Social Sciences and Education, for invaluable assistance in helping the panel organize a large volume of technical material into a coherent and readable report, as well as for her fine editorial work. We would also like to thank members of the Commission on Behavioral and Social Sciences and Education and the Committee on National Statistics who reviewed the report and proffered valuable comments.

Agnes Gaskin served ably as the administrative secretary for the panel. She made admirable logistical arrangements for the large number of meetings held by the panel—nine plenary and six working group sessions over a two-year

period. She also coped cheerfully and competently with multiple rounds of revisions to sections of this report and to the papers comprising Volume II.

Overall, the panel was ably assisted in its endeavors at every stage of the process by many, many people, whom we are honored to thank.