oTree Forum >

**#1
by
Vasu
(edited )
**

Hi, I am designing a game (akin to risk elicitation with a choice list of 10 scenarios with two options; Option A is a fixed payoff while B is a payoff based on chance with the chance varying across the 10 scenarios). There are 2 players in a group and they make choices sequentially. Player 1 makes their choice for 10 scenarios, it is then displayed to player 2 post which they make their own set of choices. Till this point, the game is working fine. Now I need to implement payoffs by randomly selecting one of the choices for each group. Say scenario 2 is selected for the group and then based on the choices of players in the group, their payoff is determined. Here is the logic for payoff determination: if both players choose the first option (Option A), then they get a certain payoff while if either of them or both choose the second option (Option B), they get a probabilistic payoff based on a coin flip as the scenario suggests. I am facing an issue in my set_payoffs function and somehow the random choice is not getting assigned to the players and the group. I am new to the oTree platform so any help regarding this will be much appreciated. The following code snippet is where I suspect my issue is coming up! class Group(BaseGroup): # Initialize payoff variables random_choice = models.IntegerField() selected_scenario = models.StringField() @staticmethod def set_payoffs(group): # Select a random choice index for the group random_choice = random.randint(0, 9) probability = C.COIN_FLIP_PROBABILITIES[random_choice] # Now set this random choice in each player's participant vars for p in group.get_players(): p.participant.vars[ 'random_choice'] = random_choice # This ensures all players in the group get the same random choice players = group.get_players() choices = [getattr(p, f'c{random_choice}') for p in players] if choices == [0, 0]: payoff = Currency(50) # Both chose option 0 else: # Coin flip with the probability specific to the choice coin_flip = random.random() < probability if coin_flip: payoff = Currency(77) # Higher payoff else: payoff = Currency(2) # Lower payoff for p in players: p.payoff = payoff p.participant.vars['random_choice'] = random_choice # Store for access in templates class Results(Page): @staticmethod def vars_for_template(player): return { 'selected_scenario': player.participant.vars['random_choice'], 'payoff': player.payoff } P.S. this is how I define coin_flip under BaseConstants: COIN_FLIP_PROBABILITIES = { 1: 0.1, # 10% chance of True for choice 1 2: 0.2, # 20% chance of True for choice 2 3: 0.3, # And so on... 4: 0.4, 5: 0.5, # Fair coin for choice 5 6: 0.6, 7: 0.7, 8: 0.8, 9: 0.9, 10: 1.0 # Always True for choice 10 }