1 Division of Epidemiology, School of Public Health, University of California, 2121 Berkeley Way, Berkeley, California, 94720, United States.
2 Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, 135 Dauer Drive, 2101 McGavran-Greenberg Hall, Chapel Hill, North Carolina, 27599, United States.
3 Carolina Population Center, University of North Carolina at Chapel Hill, 123 West Franklin Street, Chapel Hill, North Carolina, 27516, United States.
4 Division of Community Health Sciences, School of Public Health, University of California, 2121 Berkeley Way, Room 5302, Berkeley, California, 94720, United States.