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Run oTree on MTurk - How does the variable "player.id_in_group" in oTree translate to Mturk?

#1 by Daniel


I am trying to run my oTree project on Mturk and have two questions hope anyone could please help me out.

1. How does the variable "player.id_in_group" in oTree translate to Mturk? For my current oTree project, I use player.id_in_group to split participants into two groups (i.e., player.id_in_group = 1, 2, ..., 20 would be in group one; and player.id_in_group = 21, 22, ..., 40 would be in group two). Does Mturk have any ID equivalent or similar to player.id_in_group in oTree?

2. Let's assume Mturk generates some participant ID. For example, the first participant would be given ID = 1, the second would be given ID = 2, and so on. However, if a participant (ID = 2) drops out in the middle of an experiment, would the third participant coming in be given ID = 2 or ID = 3?

I am not sure if my questions make sense or not. Please don't hesitate to let me know if further explanation would be helpful.

Thank you very much in advance! :)


#2 by Chris_oTree

1. If you want 2 groups, you should set PLAYERS_PER_GROUP = 20. Then participants will be automatically be split into groups of 20. Also you may want to use group_by_arrival_time.

2. oTree does not automatically replace dropouts with other players. See this section on preventing problems due to dropouts: https://otree.readthedocs.io/en/latest/multiplayer/waitpages.html#preventing-players-from-getting-stuck-on-wait-pages

#3 by Daniel

Hello Chris, Thank you for your swift reply! It makes sense. Really appreciated.

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