對經濟學家來說，幸運的是，eBay不僅提出了問題，也給出了解決辦法。由于每天都有數不勝數的拍賣開拍，這個拍賣網站提供了大量數據。如果可以公開獲得的數據不夠用，還可以很容易地進行"現場"實驗，在出價方的自然生活環境中研究他們。

　　Fortunately for economists, eBay offers solutions as well as problems. With hundreds of thousands of auctions starting every day, the auction site provides masses of data. And if the publicly available data isn't enough, it's also easy to conduct an experiment "in the field", studying bidders in their natural habitat.

　　亞利桑那大學(University of Arizona)經濟學家戴維·賴利(David Reiley)自eBay出現之前就一直在研究網上拍賣。在最近與拉瑪·卡特卡爾(Rama Katkar)合著的一篇論文中，他對eBay拍賣中的保留價格應該公開還是保密的問題進行了研究。

　　David Reiley, an economist at the University of Arizona, has been studying online auctions since before eBay existed. In a recent paper with Rama Katkar, he investigated whether reserve prices in eBay auctions should be open or secret.

　　拍賣理論提出一種看法，認為保留價格保密更好。保留價格保密可以讓出價方看到彼此逐漸攀升的出價，從而激起他們的信心，讓他們相信自己不是唯一欣賞這件物品的人。即便出價太低、達不到保留價的水平，它們也能達到一個重要目的--安撫出價方，讓他們知道其他人也感興趣。在eBay上公開保留價格就不可能起到這種安撫作用了;任何人都不能提交低于公開保留價格的出價，而沒有任何來自其他出價方的信心信號，就可能出現沒有人出價高出保留價的危險。

　　Auction theory offers an argument that a secret reserve price is better. A secret reserve price allows bidders to see each others' gradually ascending bids and thus draw confidence that they are not alone in prizing the item. Even though the bids are too low to beat the reserve, they serve an important purpose of reassuring bidders that others are also interested. An open reserve price on eBay makes that reassurance impossible; nobody can submit a bid below the open reserve, and lacking any signs of confidence from other bidders, there is a danger that nobody may submit a bid above it either.

　　要判斷這種理論觀點在實踐中是否真的有價值，有太多不可精確估量的因素。因此，卡特卡爾和賴利通過拍賣50對匹配的收藏卡片對這個理論進行了檢驗。他們的方法是，在保留價相同的情況下，一半公開保留價，一半保密保留價。他們的結論與這種理論觀點截然相反：保密的保留價達不到預期目的。它們不是激發出價方的興趣，反而似乎是讓他們退卻，這也許是因為他們擔心，保留價之所以保密，是因為它高得離譜。由于不想浪費自己的時間，許多出價方就會點擊瀏覽器上的 "返回"鍵，再找別的地方出價。

　　There are too many imponderables to tell whether this theoretical argument is what really counts in practice. So Katkar and Reiley put the theory to the test by simply selling 50 matched pairs of collectible cards, half with an open reserve price and half with a secret reserve price of the same level. Their conclusion, contrary to the theoretic argument, is that secret reserve prices are counterproductive. Far from stimulating interest they seem to put off bidders,who perhaps fear that a secret reserve is secret because it is far too high. Not wishing to waste their time, many of them just click "back" on their browsers and find somewhere else to bid.

　　這個結論也許不會撼動世界，但方法非常重要。戴維·賴利是最早發現互聯網正在生成大量可研究數據的經濟學家之一。如今，eBay、亞馬遜(Amazon)到Match.com等眾多網站提供的這種數據，正在豐富經濟學研究。它可能也會讓少數eBay拍賣方富起來。

　　The conclusion may not shake the world but the method is important. David Reiley was one of the first economists to realise that the internet was generating vast amounts of researchable data. Now that data, from sites ranging from eBay and Amazon to Match.com, is enriching the study of economics. It may enrich a few eBay sellers, too.

　　蒂姆·哈福德的著作《臥底經濟學家》(The Undercover Economist)(小布郎出版社(Little, Brown))目前已經出版平裝本。

　　Tim Harford's book "The Undercover Economist" (Little, Brown) is out now in paperback.