1. Department of Methodology and Statistics Faculty of Health Medicine and Life Science Maastricht University Maastricht The Netherlands
2. Centre for Health Economics and Medicines Evaluation Bangor University Bangor UK
3. Faculty of Health University of Plymouth Plymouth UK
4. Department of Medical Statistics London School of Hygiene and Tropical Medicine London UK
5. MRC International Statistics and Epidemiology Group Department of Infectious Disease Epidemiology London School of Hygiene and Tropical Medicine London UK