1. Department of Health Management and Policy, Department of Economics, University of Michigan, Ann Arbor
2. National Bureau of Economic Research, Cambridge, Massachusetts
3. Division of Health Policy and Management, School of Public Health, University of Minnesota, Minneapolis
4. Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, Durham, North Carolina
5. Department of Population Health Sciences, Duke University School of Medicine, Durham, North Carolina
6. Division of General Internal Medicine, Department of Medicine, Duke University School of Medicine, Durham, North Carolina