[1] Harvard Univ, Sch Med, Dept Hlth Care Policy, Boston, MA 02115 USA
[2] Harvard Univ, Sch Publ Hlth, Dept Hlth Policy & Management, Boston, MA 02115 USA
[3] Harvard Univ, Harvard Kennedy Sch, Cambridge, MA 02138 USA
[4] Harvard Univ, Off Provost, Cambridge, MA 02138 USA
[5] Harvard Univ, Dept Econ, Cambridge, MA 02138 USA