Clustered bids in first-price auctions: Collusion or competition?
研究一级价格拍卖中两个最具竞争力出价的聚集现象，提出区分合谋与非合作策略的简单方法，需知道中标价和第二竞争者的出价决定因素。
Clustering of the two most competitive bids in first-price auctions can be indicative of collusive behavior. However, it can also reflect non-cooperative strategies under complete information. I propose a simple procedure to distinguish between the two observationally equivalent explanations. This method requires the knowledge of winning bids and the determinants of the bid of the second most competitive bidder.