1. RAND Corporation, Boston (Horvitz-Lennon), Santa Monica, California (Hollands), and Washington, D.C. (Mulcahy); Institute for Health Care Policy, Massachusetts General Hospital, Boston (Volya); Department of Health Care Policy, Harvard Medical School, Boston (Zelevinsky, Normand); Department of Biostatistics, Harvard School of Public Health, Boston (Normand); Department of Health Policy and Management, University of Pittsburgh, Pittsburgh (Donohue)