4.4. Ethical considerations

Permission for gathering data for the entire Cohort was obtained from the Ministry of Social Welfare and Health Affairs in 1993. The research plan for the 31-year follow-up study design of the Cohort named the Northern Finland Health and Well-being Study (Sorri & Järvelin 1998) was under review by the Ethics Committee of the Faculty of Medicine, University of Oulu on 17^th of June 1996. During the 31-year follow-up, after having been given a complete description of the study, the cohort members have had an opportunity to refuse the use of their data at any point of the data collection.

This study has been approved by the Dean of the Faculty of Medicine, University of Oulu, on 30^th of August 2000 as one part of the Northern Finland Health and Well-being Study. Thus, the permission by the Ethics Committee of the Faculty of Medicine on the 17^th of June, 1996, covers also the present study. In addition, on the 28^th of January 2003, this study has been approved by the Postgraduate Research Committee of the Faculty of Medicine, University of Oulu.