Collusive agreements are often observed in procurement auctions. They are probably more easily achieved when competitors’ costs are easily estimated. If, however, the individual costs of bidders are private information, effective ring formation is difficult to realize. We compare...

Collusive agreements are often observed in procurement auctions. They are probablymore easily achieved when competitors’ costs are easily estimated. If, however, the individualcosts of bidders are private information, effective ring formation is difficult to realize.We compare experimentally...