Subgroup deliberation and voting

We consider three mechanisms for the aggregation of information in heterogeneous committees voting by Unanimity rule: Private Voting and voting preceded by either Plenary or Subgroup Deliberation. While the first deliberation protocol imposes public communication, the second restricts communication to homogeneous subgroups. We find that both protocols allow to Pareto improve on outcomes achieved under private voting. Furthermore, we find that when focusing on simple equilibria under Plenary Deliberation, Subgroup Deliberation Pareto improves on outcomes achieved under Plenary Deliberation.