1. Professor at the Harvard Kennedy School of Government, Harvard University, Cambridge, Massachusetts.; Research Associates at the National Bureau of Economic Research, Cambridge, Massachusetts.
2. Department of Medicine at the Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
3. John Sloan Dickey Third Century Chair in Economics and Professor of Family and Community Medicine, Dartmouth Institute of Health Care Policy and Clinical Practice, Dartmouth College, Hanover, New Hampshire.; Research Associates at the National Bureau of Economic Research, Cambridge, Massachusetts.