11 - public goods games (part 2) Flashcards
what are issues with creating experimental games in lab
- error - games might be too complex - subject doesnt understand - subjects might think others wont understand
what is NE
each players strategy maximises their own payoff, given the strategies of the other players
what are the 2 different interpretations of NE
hold unconditionally - subjects play NE perfectly
conditionally on completion of convergence process that players learn - NE is conditional on completing learning process
what are the 3 issues with public good experimental games
- that means wont find real answer
is game theory correct - do people maximise based on what others do?
reasons why NE wont be reached?
- error
- equilibrium - is it conditional or unconditional
- control of preferences
what is the issue with controlling preferences
game theory = maximise utility
experiment = assumes utility is determined by money payoff
but what if players care about other things, money isnt the only thing that captures utility
- subjects will be playing a different game to the one experiments intended
what is the method used to implement a public good in the lab
VCM
voluntary contributions mechanismh
what is a public good
non-rival = one persons consumption of it will not reduce another persons ability to consume it
non- excludable = everybody has access to it
what is a voluntary contributions mechanism
- play game in group
- money payoffs are proportional to points earned
- each person endowed with E token - choose independently and simultaenously what to do with them
- can divide E between private account and public account
- each token in private account gives 1 point
- each token in public earns m points for everyone - m<1
- everyone benefits from public good
what is the dominant strategy in VCM
if player wants to maximise own payoff (points)
- m<1
- so will contribute nothing to public account
- all tokens in private account + whatever anyone else put in public
- if everyone doesnt contribute –> everyone gets E
what would happen if everyone contributes
- mnE points > E points (not contributing)
- everyone is better off if they all contribute everything
- if they cooperated
what are the typical findings of VCM if game is played once
- 20% free riders - dont contribute
- average contribution of endowments - 40-60%
what are typical findings of VCM if game is repeated
and you get feedback on what other members in group contributed
- contribution starts off at 50% of endowment
- decays over next rounds
- contribution rates fall
what 3 reasons explain why players contribute
- when dominant strategy is not to
(has to account for initial contribution and decay)
- error
- learning
- strategic
- preference explanations
why players contribute
error
initially they are confused about the game
- as they learn
contributions decay
why players contribute
strategic
players start by contributing in early rounds because they think it will raise future contribution of others - so they will benefit from this
- want to benefit off of the fact that others are confused (why would they think that others would contribute)
- contributions decay in later rounds to benefit from the cooperation of others