1. Department of Family and Community Medicine, University of California San Francisco, San Francisco, California, USA.
2. Healthforce Center, University of California San Francisco, San Francisco, California, USA.
3. Philip R. Lee Institute for Health Policy Studies, University of California San Francisco, San Francisco, California, USA.
4. The Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine, Lebanon, New Hampshire, USA.