Anonymity deters collusion in hard-close auctions: experimental evidence

This paper studies whether collusion occurs in three-bidder three-object second-price hard-close auctions. The experimental results of two laboratory treatments are reported. The first one, the anonymity treatment, involves subject groups that can trace decisions to the bidder under conditions of anonymity. The second one, the friends treatment, involves groups of subjects who know each other. In this treatment, each bid can be identified with a person. The paper reports no collusion in the anonymity treatment but some collusion in the friends treatment.