The Danish National Youth Study 2014: Study design, population characteristics and non-response analysis.

This paper aims to give a description of the Danish National Youth Study 2014 in terms of study design, study population and questionnaire content. The differences between participants and non-participants regarding socioeconomic characteristics are also described. The Danish National Youth Study 2014 was a web-based survey with data collected through self-completion questionnaires administered in the classroom. There were two questionnaires: one for students, with >250 core questions; and one for school leaders on the school environment. Data collection took place at 119 high schools and 10 vocational schools. A total of 75,853 students participated (70,674 high school students and 5179 vocational school students). In the participating schools, 85% of high school students and 69% of vocational school students took part in the survey. A total of 166 school leaders responded. Among the high school students, 61% were girls, and among vocational school students, 24% were girls. The average age was 17.9 years for high school students and 20.9 years for vocational school students. Participants were more likely than non-participants to be of Danish origin and to have parents with higher educational levels and a higher disposable income.