Starting day (same day of the week or absolute?)


I am wondering what the options are for the starting day of a study (that lasts 14 days for each participant). Ideally, I would like to set up a study in which participants could register via the same registration number throughout a couple of weeks, but that the starting day would always be a Sunday. Is this possible?

If I understand Ethica correctly, the alternative would be to set up multiple similar Ethica studies with different starting days, and participants would have to register via different registration numbers (depending on which day they would like to start). In this case, I would like to make use of a fixed/absolute starting day (to make sure they always start on the same day, but can sign up in the days before). I have read that it is possible to do this via JSON. I tried this, but it did not yet work. Can you tell me what I am doing wrong?

{“version”:3,“name”:“Study”,“desc”:"",“expiry_duration_ms”:14400000,“triggering_logics”:[{“id”:0,“type”:“time”,“schedule”:{“time_format”:“absolute”,“base”:“registration_date”,“period”:{“start”:“2020-13-05 12:45:00”,“end”:“2020-13-05 12:45:00”,“randomization”:{“function”:“uniform”}},“repeat”:{“occurrence_unit”:“day”,“occur_every”:1},“end”:{“criteria”:“on_count”,“last_count”:13}},“criteria”: etc.

Thank you in advance for your help!


Hi Lotte,

Unfortunately it’s not possible to allow people to join on any day and then set their participation start date on the following Sunday. The only way to achieve this is using multiple studies, one for each week, but that will make study management very complicated and I strongly advice against it.

That being said, I don’t think if this is necessary either. If you need the start date to be on Sunday for the purpose of survey scheduling, you can simply schedule the surveys such that they start on the following Sunday. This way, participants can join any day from Monday to Sunday, and the first survey their receive will start on Sunday and will continue from there.

If you need the start date to be on Sunday for the purpose of sensor-based data collection, you can start on any day of the week, and then remove the unnecessary data during the post-processing step.

Hope this helps,

Dear Mohammad,

Thank you for your help!

If I understand you correctly it is possible to schedule the surveys in a manner that their starting day will always be the next Sunday? This way, the study could actually start on the next Sunday, since we do not have any sensor-based data, just surveys. How can I make the surveys start on the next Sunday?


All you need to do is to set the survey’s Time-Triggered triggering logic to repeat once a week on Sunday: