1. Center for Social Epidemiology and Population Health, Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA
2. Research Center for Group Dynamics, Institute for Social Research, University of Michigan, Ann Arbor, MI, USA
3. Department of Health Behavior and Health Systems, School of Public Health, University of North Texas Health Science Center, Fort Worth, TX, USA
4. Department of Family Medicine, MedStar Georgetown University Hospital, Georgetown University, Washington DC, USA
5. Learning Research and Development Center, University of Pittsburgh, Pittsburgh, PA, USA