摘要：We use laboratory experiments to analyze the effects of team size in a voluntary contribution mechanism model when
contribution levels are either complementary or substitutes. A simple model shows that different team production
functions provides different incentives for its members according to team size. When contributions are substitutes
within teams, bigger groups increases free-riding by the decreasing marginal per capita return of effort. On the other
hand, if contributions are complementary within teams, in theory, group production could increase with group size.
Our results show that when efforts are substitutes the contribution level is significantly higher than when efforts are
complementary and that, for both production functions, smaller groups induce higher contribution levels.
