1. Section of Neurosurgery, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire2The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, New Hampshire
2. The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, New Hampshire
3. The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, New Hampshire3Geisel School of Medicine at Dartmouth, Hanover, New Hampshire
4. The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, New Hampshire4Department of Economics, Dartmouth College, Hanover, New Hampshire