Common-Value Auctions
Suppose that you and four other people participate in an oral auction to purchase a large jar of pennies, which will go to the winning bidder at a price equal to the highest bid. Each bidder can examine the jar but cannot open it and count the pennies. Once you have estimated the number of pennies in the jar, what is your optimal bidding strategy? This is a classic common-value auction, because the jar of pennies has the same value for all bidders. The problem for you and other bidders is the fact that the value is unknown. You might be tempted to do what many novices would do in this situation-- bid up to your own estimate of the number of pennies in the jar, and no higher This, however, is not the best way to bid. Remember that neither you nor the other bidders knows the number of pennies for certain. All of you have inde- pendently of the number, and those estimates are subject to error made estimates too then, will be the winning some will be too high and some low. Who, bidder? If each bidder bids up to his or her estimate, the winning bidder is likely to the person with the largest positive error the person with the largest overes timate of the number of pennies. THE wINNER's cuRSE To appreciate this possibility, suppose that there are actually 620 pennies in the jar. Let's say the bidders' estimates are 540, 590, 615, 650, and 690. Finally, suppose that you are the bidder whose estimate is