1. University of Cambridge; Behaviour and Health Research Unit; Forvie Site Robinson Way Cambridge UK CB2 0SR
2. University College London; Centre for Outcomes Research and Effectiveness; 1-19 Torrington Place London UK WC1E 7HB
3. University of Bristol; Population Health Sciences, Bristol Medical School; Canynge Hall, 39 Whatley Road Bristol UK BS8 2PS
4. University of Oxford; Nuffield Department of Primary Care Health Sciences; Radcliffe Observatory Quarter Woodstock Road Oxford Oxfordshire UK OX2 6GG
5. University of Cambridge; MRC Epidemiology Unit; Box 285 Cambridge Biomedical Campus Cambridge UK CB2 0QQ
6. University College London; EPPI-Centre; 10 Woburn Square London UK WC1H 0NR