网上拍卖的经济学(上)

你也许会认为，如果说有一件事经济学家应该能告诉你如何去做，那就是在拍卖网站eBay上成功登记拍卖物品。毕竟，拍卖理论家在这行享有盛名；其中一位拍卖理论家苏珊o阿西(Susan Athey)在今年4月赢得了约翰o贝茨o克拉克(John Bates Clark)经济学奖章。（克拉克奖章获得者还有保罗o萨缪尔森(Paul Samuelson)、约瑟夫o斯蒂格利茨(Joseph Stiglitz)和史蒂文o莱维特(Steven Levitt)，比诺贝尔奖(Nobel)获奖者还要罕见。）

You might think that if there's one thing an economist should be able to tell you how to do, it's successfully list an item on the auction website eBay. Auction theorists are, after all, celebrated in the profession; one of them, Susan Athey, won the John Bates Clark medal in April. (Clark medallists, who include Paul Samuelson, Joseph Stiglitz and Steven Levitt, are scarcer than Nobel laureates.)

然而，尽管拍卖理论已经很发达，但其预测容易受到现实中一些波澜的影响。比如说，标准经济学假设人是理性的，这种假设通常是对的：在啤酒价格上涨时，多数人都会少喝一些啤酒。不过，拍卖要求有"如果他认为她认为我认为他那么认为"的推理链条，而这种链条往往存在薄弱环节。如果任何出价方有任何理由怀疑其他出价方是不理性的，那么，这些环节就会轻易断裂。

Yet although the theory of auctions is well-developed, its predictions are sensitive to wrinkles in reality. For example, the standard economic assumption that people are rational is usually a good one: when the price of beer rises, most people drink less beer. But auctions require "if he thinks that she thinks that I think that he thinks" chains of reasoning that tend to have weak links. Those links can easily break if any bidder has any reason to suspect that any other bidder is irrational.

另一个理论难题是进入拍卖。多数拍卖理论家假定有固定人数的拍卖方存在，他们全都准备好了要出价。不过，虽然经济学家可以假设出价方存在，eBay的卖方却不得不去吸引这些人。

Another theoretical conundrum is entry to the auction. Most auction theorists assume a fixed number of bidders, all poised and ready to bid. But while economists can assume bidders into existence, eBay sellers have to go out and hook them.

这不是拍卖理论的一个微小疏忽。为移动电话运营商举行的大规模"3G"拍卖背后的经济学家--保罗o克伦佩雷尔(Paul Klemperer)已经表明，一场拍卖中看似微不足道的特点可能会让出价方却步，造成巨大（和灾难性的）影响。出于这些和其它原因，明智的拍卖理论家在没有充分了解整个背景的情况下，会避免预测某个具体的拍卖计划会有什么效果。

This is no minor oversight of auction theory. Paul Klemperer, one of the economists behind the massive "3G" auctions for mobile phone operators, has shown that trivial-seeming features of an auction can have big (and disastrous) effects by repelling bidders. For these reasons and others, wise auction theorists would avoid predicting how a specific auction design will work without knowing much more about the context.