Stage 4

About 18 months after stage 1, the 4th stage implies filling in another questionnaire online (a hard copy if sent by post if wished) during about 45 - 60 minutes.

This questionnaire is very similar to the first questionnaire in the first stage. It also is about the participants' socioprofessional and family background, their consumption of alcohol, cannabis and other drugs, as well as their personality.

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

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

Participants were invited to fill in this questionnaire by email. In this email, they found a personal link to the online questionnaire. Those who prefered to fill in a hard copy could get it by post with a postal-paid cover.