Cohort Study on Substance Use Risk Factors

Stages 2 & 3

Stage I Stage IV

In the eighteen months separating the two questionnaires of stages 1 & 4, participants are invited twice to update their contact details online (a hard copy is sent by post if wished).

Theses updates allow us to keep in touch with participants and seek to:

  • guarantee an ongoing participation, so that the study is the most representative possible;
  • make sure that participants receive the letters and/or emails, including incentives. It is most important that participants receive vouchers at the correct address!

At these two stages, participants are simply invited to check and confirm that their written contact details are still up-to-date, or to correct them if needed.

Each of these two updates is rewarded with a CHF 5.- voucher. The amount is added to the incentive in stage 4, once the 2nd questionnaire is filled in. © 2010-2021
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