1. Alcohol, Tobacco and Other Drug Abuse Research Unit, South African Medical Research Council, Tygerberg, South Africa
2. Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
3. RTI International, Research Triangle Park, NC, USA
4. Health, Policy and Administration, Gillings School of Global Public Health, The University of North Carolina, Chapel Hill, NC, USA
5. Department of Psychology, North Carolina State University, Raleigh, NC, USA
6. Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA