Funding for this research was provided by:
Received: 12 November 2020
Accepted: 16 January 2021
First Online: 23 January 2021
Ethics approval and consent to participate
: Although there is no formal institution for ethical assessment and approval of questionnaire-based population studies in Denmark, the X:IT II study was approved by the SDU Research and Innovation Organization. Moreover, the study is registered at the Danish Data Protection Agency (Reference Number 2015-57-0008). Parents of the students both received written information sent out by the schools and were verbally informed at a parents-teacher meeting about the purposes of this study and that participation of their child was voluntary. Students were also verbally informed by the teachers before answering the questionnaires and written information about the study was provided in the beginning of the questionnaire, including that their participation was voluntary, and their answers would be treated with confidence.
: Not applicable.
: The authors declare that they have no competing interests.