During the recruitment of the panel, respondents who agree to participate in the panel receive a confirmation email, and a letter with login code. With the login code provided they can confirm their willingness to participate and immediately start the first questionnaire, which is a general starter questionnaire for new panel members. At the end of this questionnaire, respondents are asked to read and agree to the LISS informed consent. They can confirm their agreement by ticking a checkbox. Only when respondents agree to the LISS informed consent they can become a LISS panel member. This confirmation and informed consent procedure, following the consent to participate given to the interviewer, ensures the double consent of each respondent to become a panel member and participate in the monthly panel questionnaires.
It has to be noted that ethics approvals for questionnaire research among adults are not required by law in the Netherlands. An exception is medical scientific research, which requires a medical ethical approval (according to the Dutch WMO). In general, Centerdata abides by the European "General Data Protection Regulation (GDPR)" ("Algemene verordening gegevensbescherming", AVG).