[1] Kings Coll London, Inst Psychiat, Dept Psychol, London SE5 8AF, England
[2] UCL, Dept Comp Sci, London WC1E 6BT, England
[3] Univ Politecn Cataluna, Barcelona, Spain
[4] UCL, Dept Mental Hlth Sci, Royal Free & Univ Coll Med Sch, London WC1E 6BT, England
[5] Univ Manchester, Hlth Methodol Res Grp, Sch Community Based Med, Manchester M13 9PL, Lancs, England
[6] Univ E Anglia, Sch Med, Norwich NR4 7TJ, Norfolk, England