Ethics approval and consent to participate
The research group applied for ethics approval by the Regional Committees for Medical and Health Research Ethics (REC). However, the need for approval was waived, and it was reasoned that our research is not health research. Furthermore, the Norwegian Centre for Research Data (project nr.: 49094) assessed the project and concluded that the processing of personal data is regulated by law, § 7–27 in the Personal Data Regulations. All participants and parents of the participants received written information about the aim and methods of the project, and the parents signed a consent form.