Updates are available Correction dated 2019-03-14

Article History

Received: 6 May 2016

Accepted: 8 April 2018

First Online: 25 April 2018

Change Date: 14 March 2019

Change Type: Correction

Change Details: .

Ethics approval and consent to participate

: The Norwegian Social Science Data Services (NSD) gave their approval (Reference number 34221), while the Regional Committee for Medical Research Ethics judged that the project did not require approval (REK North Reference number 2013/131), corresponding to the Norwegian regulations for ethical research practice and ethical principles stated in the Helsinki declaration. After receiving oral and written information about the design and goals of the study, all participants gave their voluntary approval for participation by signing an informed consent form.

: The authors declare that they have no competing interests.

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