1. Ludwig-Maximilians-University Munich; Institute for Medical Informatics, Biometry and Epidemiology, Pettenkofer School of Public Health; Marchioninistr. 15 Munich Bavaria Germany
2. Health Effects Institute; 101 Federal St Boston MA USA
3. Stellenbosch University; Centre for Evidence-based Health Care, Faculty of Medicine and Health Sciences; Francie van Zijl Drive Cape Town South Africa 7505
4. Cardiff University; Centre for the Development and Evaluation of Complex Interventions for Public Health Improvement (DECIPHer); 1 Museum Place Cardiff Wales UK CF10 3BD