N-Player Prisoner's Dilemma in Multiple Groups: A Model of Multilevel Selection

call attention to this fact. In this paper and in Fletcher and Zwick (2000), we make the connection between the PD and Simpson’s paradox explicit. Our main finding is that Simpson’s paradox emerges transiently, but for a wide range of PD parameter values, when a minimal group structure is imposed on an n-player PD. This result is produced in a model which involves an implicit competition between two groups and a simple n-player PD in each. The model is based on only two parameters which correlate with the within-group and between-group selection components in multilevel selection theory.