1. National Institute for Health and Welfare, Social Policy Research Unit, PO Box 30; FI-00271 Helsinki Finland
2. UKK Institute for Health Promotion Research; Tampere Finland
3. University of Tampere, School of Health Sciences and Tampere Centre for Childhood, Youth and Family Research, University of Tampere; Tampere 33014 Finland
4. School of Health Sciences and Tampere Centre for Childhood; Youth and Family Research, University of Tampere; Tampere 33014 Finland
5. Department of Adolescent Psychiatry; Tampere University Hospital; Tampere Finland