1. Department of Economics, Harvard University, 230 Littauer Center, 1805 Cambridge Street, Cambridge, MA 02138, and National Bureau of Economic Research (email: )
2. Department of Economics, Dartmouth College, Hinman Box 6106, Hanover, NH 03755, Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine, and National Bureau of Economic Research (email: )
3. Technology and Operations Management Unit, Harvard Business School, Morgan Hall 433, Boston, MA 02136, and Ariadne Labs at Brigham and Women’s Hospital and the Harvard T. H. Chan School of Public Health (email: )
4. Quartet Health, 114 West 41st Street, New York, NY 10036 (email: )