1. School of Demography, College of Arts and Social Sciences, Australian National University, Acton, ACT, Australia
2. MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
3. Institute of Behavioral Science, University of Colorado Boulder, Boulder, CO, USA
4. Melbourne School of Population and Global Health, University of Melbourne, Melbourne, VIC, Australia