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1、第二讲 不确定性、风险与信息,It is the mark of an instructed mind to rest satisfied with that degree of precision which the nature of the subject admits, and not to not to seek exactness where only an approximation of the truth is possible. Aristotle, 384-322 BC Ancient Greek philosopher,先圣哲人的看法,Precision is not
2、truth. Henri E. B. Matisse, 1869-1954 Impressionist painter,先圣哲人的看法,All traditional logic habitually assumes that precise symbols are being employed. It is therefore not applicable to this terrestrial life but only to an imagined celestial existence. Bertrand Russell, 1923 British philosopher and No
3、bel Laureate,先圣哲人的看法,信息的不确定性,在这个世界上，处处充满了不确定性。 确定的涵义 好像是 大约是 似乎是 应该是 可能是 差多是 ,不确定性与经济学,经济环境中的不确定性分为两种形式，外生不确定性和内生不确定性。 不确定性 风险 信息,导致,降低,不确定性的含义 不确定性”是凯恩斯在其就业理论中首先使用的一个概念，他认为，投资决策，取决于人们对将来会发生的事情的预期。但由于人们对未来的事情知之甚少，投资者进行投资时，对其判断的正确性非常缺乏信心，所以对投资和就业有严重影响的一般态度就容易发生突然变化。这一概念后来泛指经济活动中对未来预期的不确定性。,不确定性与经济学,确
4、定性 不确定性,不确定性与经济学,行为,结果,行为,状态 1 状态 2 状态 3,结果1,结果 3,结果2,经济活动中的不确定性 根据已经认识的可能经济环境状态的不同，经济不确定性可分为外生不确定性和内生不确定性。 根据经济活动中不确定性的性质不同，不确定性可分为随机不确定性、模糊不确定性和灰黑不确定性。 根据经济活动中不确定性的程度不同，可以将不确定性分为完全不确定性和部分不确定性。前者常常又称为不确定性，后者又称为风险性。,不确定性与经济学,不确定性与经济学,已知环境状态 确定性 环境状态 自然 外生不确定性 政策不确定性 可能环境状态 市场不确定性 内生不确定性,案例分析:拍卖中的不确定
5、性,Understanding Different Auction Types,Setting the reservethe minimum price acceptable.（预定价格）对于卖者是一个具有战略性的决定。 Choosing a buyout pricethe price at which an auction stops.（“一口价”）一些拍卖行有“一口价”，一旦达到这个价格拍卖就会停止。卖者可能会选择一个较高的“一口价”来刺激标价的攀升。,After choosing the auction type, sellers must make the following deci
6、sions:,Auction Categories: C2C, B2C, and B2B,拍卖机构组织的拍卖活动一般采用两种形式 Listing model 在列表式拍卖中，拍卖机构是严格的中介者，其职责就是把买方和卖方聚集在一起，它不拥有商品，不检查商品，也不对商品的质量起担保作用。 Merchant model 在商品式拍卖中，拍卖机构从不同的地方把商品购回，然后进行拍卖。此模式中，卖方向买方保证它们已经检查过商品，并对商品质量担保，特别是对高价商品。,不确定状态下的投标者行为,Sniping Bidders wait until the last few minutes to place
7、 a bid and because other bidders do not have enough time to respond, they better their chances of winning.投标者一直到最后几分钟才出示自己的标价，由于其他投标人没有足够的时间做出反应，投标者利用这个机会赢得拍卖。,Sniping and techniques used to prevent sniping:截止式投标及限制方法,Techniques used to prevent sniping: Offer an automatic extension period in which i
8、f there is bidding in the last five minutes the bidding is automatically extended by five minutes.由OnSale和Yahoo! 等网站采用的自动延时技术，当距离拍卖结束的最后5分钟投标还很活跃时，系统将会自动增加5分钟的拍卖时间。,Bidder Behavior (continued),Sniping and techniques used to prevent sniping: (continued),Bidder Behavior (continued),Proxy bidding代理投标ca
9、n be used so an individual can set up a proxy by specifying the highest price he or she is willing to bid. The proxy then bids on behalf of the buyer.代理投标是由eBay和其他几家网站采用的方式。每个投标者详细列出自己愿意出的最高价格，建立代理机制。代理人代表投标人逐步提高授予代理的价格。如果标价在最后几分钟被更改并且低于授予代理的最高价格，那么价格就会自动登记，使得截止式投标无效。,Bidder Behavior (continued),Shi
10、lling is the classic way by which a seller increases the price of the sale. “托儿”是卖者抬高成交价格的一种典型的方法。Shill Bidding is the artificial inflation of bid prices, by a seller who bids on his/her own auctions, or works with a friend to bid on the auctions. Shilling is illegal.卖方隐瞒真实身份提交一个高的标价，人为得提高投标水平，促成较高的
11、成交价格。这种行为是非法的。,Shilling, Bid Shielding, and Bid Siphoning:,Bidder Behavior (continued),Shilling (continued) Online auction sizes utilize a number of mechanisms to scan for suspicious bidding activity. Members are allowed to have one UserName only, so attempting to register multiple accounts will be
12、considered deceptive. If someone is asked to bid on his/her auction to help raise the bid, he/she can contact the site immediately. The site asks the bidder to bid only on those auctions where he/she is serious about purchasing. 投标者只能使用一个用户名;发现 “托儿”可与网站联系等。,Bidder Behavior (continued),Bid shielding
13、is the reverse of shilling in that it is an attempt by a buyer to ward off other bidders to keep the final price low. 屏蔽投标是“托儿”的一种逆行为，买者的目的在于避开其他的投标者以达成较低的成交价格。 The strategy is to use the high bid to discourage other bidders, and then cancel the high bid at the last minute.,Bidder Behavior (continue
14、d),Bid shielding （continued） To prevent this practice, we do not allow bid retractions. In cases of extreme events, bidders may contact auction staff to explain why they might need to have their bid cancelled. Otherwise, submitted a bid is the equivalent of entering into a contract. 不允许撤标，在一些特殊情况下，要
15、求投标人说明撤标原因。,Bidder Behavior (continued),Bid siphoning is when a seller contacts bidders on other sellers auctions, in an effort to sell a similar item thus drawing bidders away from the legitimate sellers auction. This practice is unfair to the original seller, and dangerous for buyers. The new sell
16、er has not listed the item publicly, so there will be no record of the items description, nor will there be a record of the transaction. Thus, it is extremely risky for bidders to transact with such an unethical seller.,Bidder Behavior (continued),虹吸式投标是指某卖者在与存在竞争的另一卖者的拍卖现场非法与买方达成协议，将同样的商品（以较低的成交价格）
17、卖给买方。这样做就减少了竞标者的数量，降低了成交价格。非法卖者也不必向拍卖机构交纳各种费用。虹吸式投标不仅对原卖方是不公平的，而且对于买方来说也是危险的。因为没有任何有关新参与卖方产品的公开介绍，这种交易也不会留下相关的交易记录。所以说这种交易方式对买方存在着很大的风险。,Bidder Behavior (continued),Bid siphoning (continued) To prevent Bid Siphoning, we do not display bidders User-names within single item auction listings. Because b
18、idder contact infor-mation is not released until the end of a successful edeal auction, this practice is rare on edeal.,Bidder Behavior (continued),附：winners curse（获胜者诅咒） Buyers differ in their enthusiasm for a product. The most enthusiastic will bid up the price, and the “winner” pays a price far above his or her valuation of the product. In this way, by “winning” the auction, the person loses by paying a very high price.,Bidder Behavior (continued),“获胜者诅咒” 不同的买者对同一件商品有着不同的兴趣，感兴趣的买家就会提高叫价，因此最后的赢家出的价钱会比他或她对这一商品的估价高得多。,