1. Department of Sociology, Yale University, New Haven, Connecticut, USA
2. Department of Sociology, Duke University, Durham, North Carolina, USA
3. Duke University Population Research Institute, Duke University, Durham, North Carolina, USA
4. Department of Biostatistics, Yale University, New Haven, Connecticut, USA
5. Harvard Medical School, Harvard University, Boston, Massachusetts, USA
6. Department of Epidemiology, Yale University, New Haven, Connecticut, USA