from otree.api import ( models, widgets, BaseConstants, BaseSubsession, BaseGroup, BasePlayer, Currency as c, currency_range ) import random doc = """ In a common value auction game, players simultaneously bid on the item being auctioned.
Prior to bidding, they are given an estimate of the actual value of the item. This actual value is revealed after the bidding.
Bids are private. The player with the highest bid wins the auction, but payoff depends on the bid amount and the actual value.
""" class Constants(BaseConstants): name_in_url = 'common_value_auction' players_per_group = None num_rounds = 1 instructions_template = 'common_value_auction/Instructions.html' min_allowable_bid = c(0) max_allowable_bid = c(10) # Error margin for the value estimates shown to the players estimate_error_margin = c(1) class Subsession(BaseSubsession): def creating_session(self): for g in self.get_groups(): item_value = random.uniform( Constants.min_allowable_bid, Constants.max_allowable_bid ) g.item_value = round(item_value, 1) class Group(BaseGroup): item_value = models.CurrencyField( doc="""Common value of the item to be auctioned, random for treatment""" ) highest_bid = models.CurrencyField() def set_winner(self): players = self.get_players() self.highest_bid = max([p.bid_amount for p in players]) players_with_highest_bid = [p for p in players if p.bid_amount == self.highest_bid] winner = random.choice( players_with_highest_bid) # if tie, winner is chosen at random winner.is_winner = True def generate_value_estimate(self): minimum = self.item_value - Constants.estimate_error_margin maximum = self.item_value + Constants.estimate_error_margin estimate = random.uniform(minimum, maximum) estimate = round(estimate, 1) if estimate < Constants.min_allowable_bid: estimate = Constants.min_allowable_bid if estimate > Constants.max_allowable_bid: estimate = Constants.max_allowable_bid return estimate class Player(BasePlayer): item_value_estimate = models.CurrencyField( doc="""Estimate of the common value, may be different for each player""" ) bid_amount = models.CurrencyField( min=Constants.min_allowable_bid, max=Constants.max_allowable_bid, doc="""Amount bidded by the player""" ) is_winner = models.BooleanField( initial=False, doc="""Indicates whether the player is the winner""" ) def set_payoff(self): if self.is_winner: self.payoff = self.group.item_value - self.bid_amount if self.payoff < 0: self.payoff = 0 else: self.payoff = 0