from otree.api import * 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 C(BaseConstants): NAME_IN_URL = 'common_value_auction' PLAYERS_PER_GROUP = None NUM_ROUNDS = 1 INSTRUCTIONS_TEMPLATE = 'common_value_auction/instructions.html' BID_MIN = cu(0) BID_MAX = cu(10) # Error margin for the value estimates shown to the players BID_NOISE = cu(1) class Subsession(BaseSubsession): pass class Group(BaseGroup): item_value = models.CurrencyField( doc="""Common value of the item to be auctioned, random for treatment""" ) highest_bid = models.CurrencyField() 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=C.BID_MIN, max=C.BID_MAX, doc="""Amount bidded by the player""", label="Bid amount", ) is_winner = models.BooleanField( initial=False, doc="""Indicates whether the player is the winner""" ) # FUNCTIONS def creating_session(subsession: Subsession): for g in subsession.get_groups(): import random item_value = random.uniform(C.BID_MIN, C.BID_MAX) g.item_value = round(item_value, 1) def set_winner(group: Group): import random players = group.get_players() group.highest_bid = max([p.bid_amount for p in players]) players_with_highest_bid = [p for p in players if p.bid_amount == group.highest_bid] winner = random.choice( players_with_highest_bid ) # if tie, winner is chosen at random winner.is_winner = True for p in players: set_payoff(p) def generate_value_estimate(group: Group): import random estimate = group.item_value + random.uniform(-C.BID_NOISE, C.BID_NOISE) estimate = round(estimate, 1) if estimate < C.BID_MIN: estimate = C.BID_MIN if estimate > C.BID_MAX: estimate = C.BID_MAX return estimate def set_payoff(player: Player): group = player.group if player.is_winner: player.payoff = group.item_value - player.bid_amount if player.payoff < 0: player.payoff = 0 else: player.payoff = 0 # PAGES class Introduction(Page): @staticmethod def before_next_page(player: Player, timeout_happened): group = player.group player.item_value_estimate = generate_value_estimate(group) class Bid(Page): form_model = 'player' form_fields = ['bid_amount'] class ResultsWaitPage(WaitPage): after_all_players_arrive = set_winner class Results(Page): @staticmethod def vars_for_template(player: Player): group = player.group return dict(is_greedy=group.item_value - player.bid_amount < 0) page_sequence = [Introduction, Bid, ResultsWaitPage, Results]