1. Department of Family Medicine, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA.
2. Cecil G. Sheps Center for Health Services Research, UNC-Chapel Hill, Chapel Hill, North Carolina, USA.
3. Department of Health Policy and Management, Gillings School of Public Health, UNC-Chapel Hill, Chapel Hill, North Carolina, USA.
4. Department of Political Science and Criminal Justice, California State University, Chico, California, USA.
5. Department of Health Policy and Management, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
6. Department of Health Services, Policy and Practice, School of Public Health, Brown University, Providence, Rhode Island, USA.
7. Department of Health Management and Policy, College of Public Health, University of Iowa, Iowa City, Iowa, USA.