microeconomicuncertaintyandinformation(编辑修改稿)

microeconomicuncertaintyandinformation(编辑修改稿)内容摘要：

e of a used car? Private Information 169。 2020 Pearson AddisonWesley So the most that the buyer knows is the probability of buying a lemon. If half of the used cars sold turn out to be lemons, the buyer know that he has a 50 percent chance of getting a good car and a 50 percent chance of getting a lemon. The price that a buyer is willing to pay for a car of unknown quality is more than the value of a lemon because the car might be a good one. But the price is less than the value of a good car because it might turn out to be a lemon. Private Information 169。 2020 Pearson AddisonWesley Sellers of used cars know the quality of their cars. Someone who owns a good car is going to be offered a price that is less than the value of that car to the buyer. Many owners will be reluctant to sell, so fewer good cars will be supplied than if the price reflected its value. But someone who owns a lemon is going to be offered more than the value of that car to the buyer. Owners of lemons will be eager to sell, so more lemons will be supplied than if the price reflected its value. Private Information 169。 2020 Pearson AddisonWesley In the used car market: Adverse selection exists because there is a greater incentive to offer a lemon for sale. Moral hazard exists because the owner of a lemon has little incentive to take good care of the car, so it is likely to bee even worse. The market for used cars is not working well. Private Information 169。 2020 Pearson AddisonWesley Figure illustrates the used car market. Part (a) shows the used car market. Equilibrium price is $10,000 a car and 400 cars traded. Private Information 169。 2020 Pearson AddisonWesley Part (b) shows the demand and supply of good cars. At $10,000 a car, 200 good cars are traded. Private Information 169。 2020 Pearson AddisonWesley Buyers are willing to pay $25,000 for a good car. Too few good cars are traded. A deadweight loss is created. Private Information 169。 2020 Pearson AddisonWesley Part (c) shows the demand and supply of lemons. At $10,000 a car, 200 lemons are traded. Private Information 169。 2020 Pearson AddisonWesley Buyers are willing to pay $5,000 for a lemon. Too many lemons are traded. A deadweight loss is created. Private Information 169。 2020 Pearson AddisonWesley A Used Car Market with Dealers’ Warranties Buyers can’t tell a lemon from a good car, but car dealers sometimes can. To convince a buyer to pay $10,000 for what might be a lemon, the dealer offers a warranty. The dealer signals which cars are good ones and which are lemons. Signaling occurs when an informed person takes actions that send information to uninformed persons. Warranties enable the market to trade good used cars. Private Information 169。 2020 Pearson AddisonWesley Figure shows how warranties solve the lemon problem. Part (a) shows the market for good cars. With warranties, the price of a good car is $20,000 and 400 good cars are traded. The market for good cars is efficient. Private Information 169。 2020 Pearson AddisonWesley Part (b) shows the market for lemons. Because buyers can now spot a lemon (a car without a warranty) … the price of a lemon is $6,667 and 150 lemons are traded. The market for lemons is efficient. Private Information 169。 2020 Pearson AddisonWesley Pooling Equilibrium and Separating Equilibrium Without warranties, only one message is visible to the buyer: All cars look the same. The market equilibrium when only one message is available and an uninformed person cannot determine quality is a pooling equilibrium . Private Information 169。 2020 Pearson AddisonWesley In a market with warranties, there are two messages: Cars with warranties are good cars and cars without warranties are lemons. The market equilibrium when signaling provides full information to a previously uninformed person is a separating equilibrium. Private Information 169。 2020 Pearson AddisonWesley The Market for Loans Borrowers demand loans. The lower the interest rate, the greater is the quantity of loans demanded. Banks and other lenders supply loans. For a given credit risk, the higher the interest rate the greater is the quantity of loans supplied. Private Information 169。 2020 Pearson AddisonWesley The risk that a borrower, also called a creditor, might not repay a loan is called credit risk or default risk. The credit risk depends on the quality of the borrower. Lowrisk borrowers always repay. Highrisk borrowers frequently default on their loans. The market for loans determines the interest rate and the price of credit risk. Private Information 169。 2020 Pearson AddisonWesley Inefficient Pooling Equilibrium Suppose that banks cannot tell whether they are lending to a lowrisk or a highrisk customer. In this situation, all borrowers pay the same interest rate and the market is a pooling equilibrium. The market for loans has the same problems as the used car market without warranties. Private Information 169。 2020 Pearson AddisonWesley If all borrowers pay the same interest rate, lowrisk customers borrow less than they would if they were offered the low interest rate appropriate for their low credit risk. Highrisk customers borrow more than they would if they faced the high interest rate appropriate for their high credit risk. So banks face an adverse selection problem. Too many borrowers are high risk and too few are low risk. Private Information 169。 2020 Pearson AddisonWesley Signaling and Screening in the Market for Loans Lenders don’t know how likely a given loan will be repaid, but the borrower does know. Lowrisk borrowers have an incentive to signal their risk by providing lenders with relevant information. Signals might include information about a person’s employment, home。