Text and Data Mining valid from 2019-01-29
Received: 22 October 2018
Accepted: 18 January 2019
First Online: 29 January 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This research involves human participants.
: Informed consent was obtained from all who participated in the study. A consent form was signed electronically by the subjects before the data was collected to make the subjects eligible for participation. The data collected are kept confidential. The data do not identify the subjects from which it was collected, other than to the two investigators. Electronic data are stored in password protected files on a secure computer accessible only by the investigators.