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Limiting participant number per group

#1 by hussein

Hello Otree-Community!

I have a quick question. Is it possible to limit the number of participants? I need 3 groups with 50 participants each. My problem is that if i limit the participants in my otree project and someone leaves the experiment before finishing (Prolific), the spot gets blocked and the max. number of my participants drops by one. Is there a way to just set a cap per group for finished experiments?

Sorry for my english, I hope I have made my point clear.
Thanks for you help :)

#2 by Chris_oTree

What I understand is that you want to ensure 150 participants finish the study, but no more. Is that correct?

#3 by hussein

Exactly! Sorry for the late response :(

#4 by hussein

Hello Chris, i hope you are doing well. I took screenshots from the pre-test to show you the problem. P10 for example is one of the participants who returned but in my Otree Data he/she is still listed and is blocking a spot. Do you know a fix for that?

Thank you for your time! :)

#5 by Chris_oTree

Create a session with more than 150 participants, to account for the highest number of dropouts you think you might have. Define a session field, like session.num_finished, to count how many people have finished the study. Each time someone completes, increment it by 1. Then on the first page of the study, when someone starts, check if session.num_finished >= 150. If yes, direct them to a page that tells them the session is full.

Also, make sure to use group_by_arrival_time so that if someone drops out prior to the multiplayer task, they will not be part of the group.

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