1. Centre for Mental Health, Imperial College London.
2. School of Social and Community Medicine, University of Bristol, UK.
3. Department of Psychological Medicine, University of Otago, Wellington, New Zealand.
4. Statsconsultancy Ltd., Amersham, UK.
5. Central and North West London NHS Foundation Trust.
6. Department of Psychological Medicine, University of Otago, Christchurch, New Zealand.