from otree.api import * c = Currency doc = """ This is a standard 2-player trust game where the amount sent by player 1 gets tripled. The trust game was first proposed by Berg, Dickhaut, and McCabe (1995) . """ class Constants(BaseConstants): name_in_url = 'trust' players_per_group = 2 num_rounds = 1 instructions_template = 'trust/instructions.html' # Initial amount allocated to each player endowment = c(10) multiplier = 3 class Subsession(BaseSubsession): pass class Group(BaseGroup): sent_amount = models.CurrencyField( min=0, max=Constants.endowment, doc="""Amount sent by P1""", label="How much will you send to Player B?", ) kept_A = models.CurrencyField( min=0, max=Constants.endowment, doc="""Amount kept by Player A""", label="How much will you keep?", ) kept_B = models.CurrencyField( min=0, max=Constants.endowment, doc="""Amount kept by Player B""", label="How much will you keep?", ) sent_back_amount = models.CurrencyField(doc="""Amount sent back by P2""", min=c(0)) class Player(BasePlayer): pass # FUNCTIONS def sent_back_amount_max(group: Group): return group.sent_amount * Constants.multiplier def set_payoffs(group: Group): p1 = group.get_player_by_id(1) p2 = group.get_player_by_id(2) p1.payoff = Constants.endowment - group.sent_amount + group.sent_back_amount p2.payoff = Constants.endowment + (group.sent_amount * Constants.multiplier) - group.sent_back_amount # PAGES class Introduction(Page): pass class Send(Page): """This page is only for P1 P1 sends amount (all, some, or none) to P2 This amount is tripled by experimenter, i.e if sent amount by P1 is 5, amount received by P2 is 15""" form_model = 'group' form_fields = ['sent_amount', 'kept_A'] @staticmethod def is_displayed(player: Player): return player.id_in_group == 1 @staticmethod def error_message(group, values): if values['kept_A'] + values['sent_amount'] != 10: return "The numbers must add up to 10" class SendBackWaitPage(WaitPage): pass class SendBack(Page): """This page is only for P2 P2 sends back some amount (of the tripled amount received) to P1""" form_model = 'group' form_fields = ['sent_back_amount', 'kept_B'] @staticmethod def is_displayed(player: Player): return player.id_in_group == 2 @staticmethod def error_message(group, values): if values['kept_B'] + values['sent_back_amount'] != 10: return "The numbers must add up to " + str(p2sum) class ResultsWaitPage(WaitPage): after_all_players_arrive = set_payoffs class Results(Page): """This page displays the earnings of each player""" @staticmethod def vars_for_template(player: Player): group = player.group return dict(tripled_amount=group.sent_amount * Constants.multiplier, p2sum = (group.sent_amount * Constants.multiplier) + Constants.endowment) page_sequence = [ Introduction, Send, SendBackWaitPage, SendBack, ResultsWaitPage, Results, ]