Advanced Grouping¶

Grouping by arrival time `group_by_arrival_time = True`¶

We can group participants by arrival time by setting the attribute group_by_arrival_time = True directly under a WaitPage.

Things to consider

group_by_arrival_time is defined on pages.py under a page class, unlike previous matching commands.
group_by_arrival_time copies the group structure to future rounds. If a group is rematched, the value is overwritten.
group_by_arrival_time works only if the WaitPage is the first page in the app

You can use is_displayed to keep the group structure in the first round only (but every player should see the page)

 class GroupPage(WaitPage):
     group_by_arrival_time = True

     def is_displayed(self):
         return self.round_number == 1

If group_by_arrival_time = True all players will be initially in the same group when creating_session runs.
id_in_group is not assigned in order participants arrive
A group’s id_in_subsession is not necessarily goes from 1 to number of groups. In each grouping a new number is created.

Practice: Rubinstein Bargaining Game Apps