[1] Oxford Brookes Univ, Ctr Psychol Res, Gipsy Lane, Oxford, England
[2] Univ Liverpool, Dept Psychol, Liverpool, Merseyside, England
[3] Liverpool Ctr Alcohol Res, Liverpool, Merseyside, England
[4] Univ Calif San Francisco, Dept Psychiat, San Francisco, CA USA
[5] Swiss Natl Sci Fdn, Bern, Switzerland
[6] UCL, Inst Epidemiol & Hlth, London, England
[7] Global Drug Survey, London, England
[8] Univ Queensland, Ctr Hlth Serv Res, Brisbane, Qld, Australia