title: Response rates and selection problems, with emphasis on mental health variables and DNA sampling, in large population-based, cross-sectional and longitudinal studies of adolescents in Norway.
authors.affiliation: Section for Preventive Medicine and Epidemiology, Institute of General Practice and Community Medicine, Faculty of Medicine, University of Oslo, Box 1130 Blindern, 0318 Oslo, Norway. espen.bjertness@medisin.uio.no
authors.forename: Espen
authors.initials: E
authors.lastname: Bjertness
authors.forename: Ase
authors.initials: A
authors.lastname: Sagatun
authors.forename: Kristian
authors.initials: K
authors.lastname: Green
authors.forename: Lars
authors.initials: L
authors.lastname: Lien
authors.forename: Anne Johanne
authors.initials: AJ
authors.lastname: Søgaard
authors.forename: Randi
authors.initials: R
authors.lastname: Selmer