TY - JOUR AU - Bjertness, Espen AU - Sagatun, Åse AU - Green, Kristian AU - Lien, Lars AU - Søgaard, Anne Johanne AU - Selmer, Randi PY - 2010 DA - 2010/10/12 TI - 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 JO - BMC Public Health SP - 602 VL - 10 IS - 1 AB - Selection bias is a threat to the internal validity of epidemiological studies. In light of a growing number of studies which aim to provide DNA, as well as a considerable number of invitees who declined to participate, we discuss response rates, predictors of lost to follow-up and failure to provide DNA, and the presence of possible selection bias, based on five samples of adolescents. SN - 1471-2458 UR - https://doi.org/10.1186/1471-2458-10-602 DO - 10.1186/1471-2458-10-602 ID - Bjertness2010 ER -