1. Department of Sociology, Stanford University, Palo Alto, CA, California, USA
2. Department of General Internal Medicine, Boston University School of Medicine, Boston, MA, USA
3. Department ofSociology, Harvard University, Cambridge, MA, USA
4. Center for Outcomes Research and Evaluation, Maine Medical Center Research Institute, Scarborough, ME, USA
5. Department of Health Policy and Management, Boston University School of Public Health, Boston, MA, USA
6. Center for Healthcare Organization and Implementation Research, ENRM VA Hospital, Bedford, MA, USA
7. Department of Obstetrics and Gynecology, Boston University School of Medicine/Boston Medical Center, Boston, MA, USA