*From the School of Public Health, Division of Health Policy and Management, University of California, Berkeley, California.†From the Department of Surgery, School of Medicine, Duke University, Durham, North Carolina.‡From the Department of Preventive Medicine, Northwestern University Medical School, Chicago, Illinois.§From the J.L. Kellogg Graduate School of Management, Northwestern University, Evanston, Illinois.¶From the Department of Preventive Medicine, J.L. Kellogg Graduate School of Management, and Institute for Health Services Research and Policy Studies, Northwestern University, Chicago and Evanston, Illinois.∥From the Institute for Health Services Research and Policy Studies, Northwestern University, Evanston, Illinois.