1 Psychiatry and Applied Psychology, Institute of Mental Health, University of Nottingham, Nottingham NG7 2UH, UK. Electronic address: richard.morriss@nottingham.ac.uk.
2 Center for Clinical Trials and Evidence Synthesis, Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
3 National Collaborating Centre for Mental Health, London, UK; Sheffield Health and Social Care National Health Service Foundation Trust, Sheffield, UK.