Voluntary Participation in Collective Goods Games in a Growing Group:

Introduction of Group Reputation Mechanism

Abstract

     The purpose of this study is to clarify how the increase in the number of members of a group affects cooperation. Most of the previous works focused on static one-shot games. This study, however, focuses on repeated games, more specificlly stochastic/dynamic games that enable us to analyze games in which the number of players changes, especially becomes larger, by degrees. In addition, we do not assume a simple way to increase in the number of players but assume Group Reputation Mechanism (hereafter GRM) in which the number of cooperating players in the group in the previous game affects how many players outside the group join the group. We find that GRM, in which the number of new members is proportion to the number of players who cooperate in the previous game, allows players to cooperate without any sanction in the pure collective goods which are characterized non-excludability and non-rivalness.