Stage 1

Shortly after consent, the first stage implies filling in a questionnaire online (a hard copy if sent by post if wished) during about 45 - 60 minutes.

This questionnaire is about the participants' socioprofessional and family background, their consumption of alcohol, cannabis and other drugs, as well as their personality.

This stage is rewarded with a CHF 30.- voucher, which is sent shortly after the questionnaire is filled in.

Participants who filled in both questionnaires in stages 1 & 4 get another CHF 30.- voucher.

Participants are invited to fill in this questionnaire by email. In this email, they find a personal link to the online questionnaire. Those who prefer to fill in a hard copy can get it by post with a postal-paid cover. They also receive a personal access code to the questionnaire online, in case their found it more convenient.

If any problem should come up or for questions related to the study or the questionnaire, participants can get in touch with our project adminstrator at the University Hospital of the Canton Vaud (  or at 021 314 90 07).