1. Tobacco Research Department, Population Health Research Center, Mexican National Institute of Public Health, Cuernavaca, Mexico.
2. Health Services of Morelos, Secretary of Health, Cuernavaca, Mexico.
3. Center for Evaluation and Survey Research, Mexican National Institute of Public Health, Cuernavaca, Mexico.
4. Epidemiology and Health Services Research Unit, Mexican Institute of Social Security, Cuernavaca, Mexico.
5. Department of Population Health, New York University Grossman School of Medicine, New York, New York, USA.
6. Department of Health Promotion, Education and Behavior, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, USA.