Hi! 
I would like to assign randomly the participants I have in a session into the 2 apps I have in my code. The apps I have are "control" and "treatment" and the difference between them are that the first one has a time limit of 15 minutes and the second one a time limit of 5 minutes. After the main questions that have time limit, there are some final questions that are the same for everyone. I've been reading the oTree documentation about Treatment but I don't see the explanation on how to assign the participants into different apps, so I would like to know if it's possible or if it's not, then how could I implement different time limits depending of the assignment of the participant into control or treatment in one app? I didn't see either how to assign different time limits depending the treatment assigned to the participant.

Thank you very much!

Hi there!

Is the only difference of the treatments the different countdown?

If yes, you can show the participants the same page with different timeouts using get_timeout_seconds: 

class YourPage(Page):
    @staticmethod
    def get_timeout_seconds(player):
        # I assume you have saved the assigned treatment in a player-field
        if player.treatment == 'control':
            timeout_seconds = 5 * 60
        if player.treatment == 'treatment':
            timeout_seconds = 15 * 60
            
        return timeout_seconds
        
If you want to send the players to different apps, you can use app_after_this_page: https://otree.readthedocs.io/en/latest/pages.html?highlight=app_after_this_page#app-after-this-page

Thank you so much for your help!
As I am modifying an existing code, I am thinking of implementing the second method. In that case, should I hardcode the exact page each player will go?
Again, I appreciate the help

I created this new app in order to assign each participant randomly to either the treat app or the control app but I don't know what error I'am making:

import random

from otree.api import *


class C(BaseConstants):
    NAME_IN_URL = 'gbat_treatments'
    PLAYERS_PER_GROUP = None  # You can set this to a specific number if needed
    NUM_ROUNDS = 1


class Subsession(BaseSubsession):
    pass


class Group(BaseGroup):
    pass

class Player(BasePlayer):
    treatment = models.BooleanField()

class MyWaitPage(WaitPage):
    def creating_session(subsession):
        if subsession.round_number == 1:
            for player in subsession.get_players():
                participant = player.participant
                participant.treatment = random.choice([True, False])

class MyPage(Page):
    def app_after_this_page(self, player):
        participant = player.participant
        if participant.treatment:
            return "treat"
        else:
            return "control"

page_sequence = [MyWaitPage]

creating_session should be on the top level of your code (usually placed after the class Subsession), not on the WaitPage:

...
class Subsession(BaseSubsession):
    pass


def creating_session(subsession):
    if subsession.round_number == 1:
        # save the players in a local list, so the function get_players() is only executed once
        all_players = subsession.get_players()
        for player in all_players:
            participant = player.participant
            participant.treatment = random.choice([True, False])
            
            
class Group(BaseGroup):
    pass


class Player(BasePlayer):
    treatment = models.BooleanField()
    

class MyWaitPage(WaitPage):
    pass
    
    
class MyPage(Page):
    @staticmethod
    def app_after_this_page(player, upcoming_apps):
        participant = player.participant
        if participant.treatment:
            return "treat"
        else:
            return "control"
            

# you need to add MyPage to the page_sequence, otherwise you cannot sort the players into the different apps
page_sequence = [MyWaitPage, MyPage]

Furthermore, player.treatment and player.participant.treatment are two different variables: you initiate player.treatment in the Player class, but use player.participant.treatment for the treatment-assignment.

Hope that helps!

Best,
Daniel