1. Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands and Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark
2. Department of Philosophy, University of Johannesburg, Auckland Park, South Africa
3. Department of Medical Statistics and Centre for Global NCDs, London School of Hygiene and Tropical Medicine, London, UK and Centre for Public Health Research, Massey University, Wellington, New Zealand