Received: 23 October 2019
Accepted: 23 April 2020
First Online: 7 May 2020
Ethics approval and consent to participate
: Data were obtained from an already established data material collected anonymously in the Ungdata survey. The data collection was based on informed consent. Norwegian Centre for Research Data (NSD) and Norwegian Social Research institute (NOVA) have assessed that the data collection is in line with the privacy protections and regulations. Further ethical approval for the present study was not necessary as the study use anonymised data.
: Not applicable.
: The authors declare that they have no competing interests.