1. Health Services Research, Health Services, Norwegian Institute of Public Health, Postbox 222 Skøyen, 0213 Oslo, Norway
2. Norwegian System of Patient Injury Compensation, Postboks 232 Skøyen, 0213 Oslo, Norway
3. Faculty of Landscape and Society, Norwegian University of Life Sciences, Universitetstunet 3, 1430 Ås, Oslo, Norway
4. Research Committee, Helgelandssykehuset HF, Postboks 601, 8607 Mo i Rana, Norway