In a range of settings, private firms manage peer effects by sorting agents into different groups, be they schools, neighbourhoods or teams. This paper considers such a firm, which controls group entry by setting a series of anonymous prices. We show that private provision systematically leads...

We consider the design of an optimal voting system when voting is costly. For a private values model with two alternatives we show the optimality of a voting system that combines three elements: (i) there is an arbitrarily chosen default decision and non-participation is interpreted as a vote in...