1. Usher Institute, Edinburgh Medical School, University of Edinburgh, Edinburgh, EH16 4UX UK
2. MRC/CSO Social & Public Health Sciences Unit, University of Glasgow G3 7HR, Glasgow, UK
3. Department of Mathematics and Statistics, University of Strathclyde, Glasgow, G1 1XH UK
4. School of Medicine, University of St. Andrews, St Andrews, KY16 9TF UK
5. School of Health, Wellington Faculty of Health, Victoria University of Wellington, PO Box 600,Wellington 6140 New Zealand
6. The National Institute for Health Research Applied Research Collaboration West (NIHR ARC West) at University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, BS1 2NT, UK
7. Public Health Scotland, Glasgow, G2 6QE UK
8. Academic Primary Care, University of Aberdeen School of Medicine and Dentistry, Aberdeen, AB24 3FX UK