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

摘要

BackgroundSelection 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.