1. School of Social and Political Sciences, Adam Smith Building, 28 Bute Gardens, Glasgow G12 8RS, UK
2. MRC/CSO Social and Public Health Sciences Unit, University of Glasgow G3 7H3, UK
3. Usher Institute, University of Edinburgh, Edinburgh EH8 9AG, UK
4. Directorate of Public Health, NHS Tayside, Dundee DD1 9AG, UK