1. Health Behavior and Health Education, and
2. Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
3. ISLES, Inc., Trenton, New Jersey USA
4. Duke University, Durham, North Carolina, USA
5. Survey Research Center and Department of Sociology, and
6. Institute for Social Research and Department of Biostatistics, University of Michigan, Michigan, Ann Arbor, USA