平新乔《微观经济学十八讲》课后习题详解(第17讲 外在性、科斯定理与公共品理论)
平狄克《微观经济学》课后答案 18
CHAPTER 18EXTERNALITIES AND PUBLIC GOODSThis chapter extends the discussion of market failure begun in Chapter 17. To avoid over-emphasis on definitions, stress the main theme of the chapter: the characteristics of some goods lead to situations where price is not equal to marginal cost. Rely on the discussion of market power (Chapter 10) as an example of market failure. Also, point out with each case that government intervention might not be required if property rights can be defined and transaction costs are small (Section 18.3). The first four sections present positive and negative externalities and solutions to market failure. The last two sections discuss public goods and public choice.The consumption of many goods involves the creation of externalities. Stress the divergence between social and private costs. Exercise (5) presents the classic beekeeper/apple-orchard problem, originally popularized in Meade, “External Economies and Diseconomies in a Competitive Situation,” Economic Journal (March 1952). Empirical research on this example has shown that beekeepers and orchard owners have solved many of their problems: see Cheung, “The Fable of the Bees: An Economic Investigation,” Journal of Law and Economics (April 1973).Solutions to the problems of externalities are presented in Sections 18.2 and 18.3. Section 18.2, in particular, discusses emission standards, fees, and transferable permits. Example 18.1 and Exercise (3) are simple applications of these concepts.One of the main themes of the law and economics literature since 1969 is the application of Coase’s insight on the assignment of property rights. The original article is clear and can be understood by students. Stress the problems posed by transactions costs. For a lively debate, ask students whether non-smokers should be granted the right to smokeless air in public places (see Exercise (4)). For an extended discussion of the Coase Theorem at the undergraduate level, see Polinsky, Chapters 3-6, An Introduction to Law & Economics (Little, Brown & Co., 1983).The section on common property resources emphasizes the distinction between private and social marginal costs. Example 18.5 calculates the social cost of unlimited access to common property, and the information provided is used in Exercise (7). Exercise (8) provides an extended example of managing common property.The last two sections focus on public goods and private choice. Point out the similarities and differences between public goods and other activities with externalities. Since students confuse nonrival and nonexclusive goods, create a table similar to the following and give examples to fill in the cells:The next stumbling block for students is achieving an understanding of why we add individual demand curves vertically rather than horizontally. Exercise (6) compares vertical and horizontal summation of individual demand.The presentation of public choice is a limited introduction to the subject, but you can easily expand on this material. A logical extension of this chapter is an introduction to cost-benefit analysis. For applications of this analysis, see Part III, “Empirical Analysis of Policies and Programs,” in Haveman and Margolis (eds.), Public Expenditure and Policy Analysis (Houghton Mifflin, 1983).1. Which of the following describes an externality and which does not? Explain the difference.a. A policy of restricted coffee exports in Brazil causes the U.S. price of coffee to rise,which in turn also causes the price of tea to increase.Externalities cause market inefficiencies by preventing prices from conveying accurateinformation. A policy of restricting coffee exports in Brazil causes the U.S. price ofcoffee to rise, because supply is reduced. As the price of coffee rises, consumers switchto tea, thereby increasing the demand for tea, and hence, increasing the price of tea.These are market effects, not externalities.b. An advertising blimp distracts a motorist who then hits a telephone pole.An advertising blimp is producing information by announcing the availability of somegood or service. However, its method of supplying this information can be distractingfor some consumers, especially those consumers who happen to be driving neartelephone poles. The blimp is creating a negative externality that influences thedrivers’ safety. Since the price charged by the advertising firm does not incorporate theexternality of distracting drivers, too much of this type of advertising is produced fromthe point of view of society as a whole.2. Compare and contrast the following three mechanisms for treating pollution externalities when the costs and benefits of abatement are uncertain: (a) an emissions fee, (b) an emissions standard, and (c) a system of transferable emissions permits.Since pollution is not reflected in the marginal cost of production, its emission createsan externality. Three policy tools can be used to reduce pollution: an emissions fee, anemissions standard, and a system of transferable permits. The choice between a feeand a standard will depend on the marginal cost and marginal benefit of reducingpollution. If small changes in abatement yield large benefits while adding little to cost,the cost of not reducing emissions is high. Thus, standards should be used. However, ifsmall changes in abatement yield little benefit while adding greatly to cost, the cost ofreducing emissions is high. Thus, fees should be used.A system of transferable emissions permits combines the features of fees and standardsto reduce pollution. Under this system, a standard is set and fees are used to transferpermits to the firm that values them the most (i.e., a firm with high abatement costs).However, the total number of permits can be incorrectly chosen. Too few permits willcreate excess demand, increasing price and inefficiently diverting resources to ownersof the permits. Typically, pollution control agencies implement one of threemechanisms, measure the results, reassess the success of their choice, then reset newlevels of fees or standards or select a new policy tool.3. When do externalities require government intervention, and when is such intervention unlikely to be necessary?Economic efficiency can be achieved without government intervention when theexternality affects a small number of people and when property rights are wellspecified. When the number of parties is small, the cost of negotiating an agreementamong the parties is small. Further, the amount of required information (i.e., the costsof and benefits to each party) is small. When property rights are not well specified,uncertainty regarding costs and benefits increases and efficient choices might not bemade. The costs of coming to an agreement, including the cost of delaying such anagreement, could be greater than the cost of government intervention, including theexpected cost of choosing the wrong policy instrument.4. An emissions fee is paid to the government, whereas an injurer who is sued and is held liable pays damages directly to the party harmed by an externality. What differences in the behavior of victims might you expect to arise under these two arrangements?When the price of an activity that generates an externality reflects social costs, anefficient level of the activity is maintained. The producer of the externality reduces (fornegative externalities) or increases (for positive externalities) activity away from(towards) efficient levels. If those who suffer from the externality are not compensated,they find that their marginal cost is higher (for negative externalities) or lower (forpositive externalities), in contrast to the situation in which they would be compensated.5. Why does free access to a common property resource generate an inefficient outcome?Free access to a resource means that the marginal cost to the user is less than the socialcost. The use of a common property resource by a person or firm excludes others fromusing it. For example, the use of water by one consumer restricts its use by another.Because private marginal cost is below social marginal cost, too much of the resource isconsumed by the individual user, creating an inefficient outcome.6. Public goods are both nonrival and nonexclusive. Explain each of these terms and state clearly how they differ from each other.A good is nonrival if, for any level of production, the marginal cost of providing the goodto an additional consumer is zero (although the production cost of an additional unitcould be greater than zero). A good is nonexclusive if it is impossible or very expensiveto exclude individuals from consuming it. Public goods are nonrival and nonexclusive.Commodities can be (1) exclusive and rival, (2) exclusive and nonrival, (3) nonexclusiveand rival, or (4) nonexclusive and nonrival. Most of the commodities discussed in thetext to this point have been of the first type. In this chapter, we focus on commodities ofthe last type.Nonrival refers to the production of a good or service for one more customer. It usuallyinvolves a production process with high fixed costs, such as the cost of building ahighway or lighthouse. (Remember that fixed cost depends on the period underconsideration: the cost of lighting the lamp at the lighthouse can vary over time, butdoes not vary with the number of consumers.) Nonexclusive refers to exchange, wherethe cost of charging consumers is prohibitive. Incurring the cost of identifyingconsumers and collecting from them would result in losses. Some economists focus onthe nonexclusion property of public goods because it is this characteristic that poses themost significant problems for efficient provision.7. Public television is funded in part by private donations, even though anyone with a television set can watch for free. Can you explain this phenomenon in light of the free rider problem?The free-rider problem refers to the difficulty of excluding persons from consuming anonexclusive commodity. Non-paying consumers can “free-ride” on commoditiesprovided by paying customers. Public television is funded in part by contributions.Some viewers contribute, but most watch without paying, hoping that someone else willpay so they will not. To combat this problem these stations (1) ask consumers to assesstheir true willingness to pay, then (2) ask consumers to contribute up to this amount,and (3) attempt to make everyone else feel guilty for free-riding.8. Explain why the median voter outcome need not be efficient when majority rule voting determines the level of public spending.The median voter is the citizen with the middle preference: half the voting population ismore strongly in favor of the issue and half is more strongly opposed to the issue.Under majority-rule voting, where each citizen’s vote is weighted equally, the preferredspending level on public-goods provision of the median voter will win an electionagainst any other alternative.However, majority rule is not necessarily efficient, because it weights each citizen’spreferences equally. For an efficient outcome, we would need a system that measuresand aggregates the willingness to pay of those citizens consuming the public good.Majority rule is not this system. However, as we have seen in previous chapters,majority rule is equitable in the sense that all citizens are treated equally. Thus, weagain find a trade-off between equity and efficiency.1. A number of firms located in the western portion of a town after single-family residences took up the eastern portion. Each firm produces the same product and, in the process, emits noxious fumes that adversely affect the residents of the community.a. Why is there an externality created by the firms?Noxious fumes created by firms enter the utility function of residents. We can assumethat the fumes decrease the utility of the residents (i.e., they are a negative externality)and lower property values.b. Do you think that private bargaining can resolve the problem with the externality?Explain.If the residents anticipated the location of the firms, housing prices should reflect thedisutility of the fumes; the externality would have been internalized by the housingmarket in housing prices. If the noxious fumes were not anticipated, privatebargaining could resolve the problem of the externality only if there are a relativelysmall number of parties (both firms and families) and property rights are well specified.Private bargaining would rely on each family’s willingness to pay for air quality, buttruthful revelation might not be possible. All this will be complicated by theadaptability of the production technology known to the firms and the employmentrelations between the firms and families. It is unlikely that private bargaining willresolve the problem.c. How might the community determine the efficient level of air quality?The community could determine the economically efficient level of air quality byaggregating the families’ willingne ss to pay and equating it with the marginal cost ofpollution reduction. Both steps involve the acquisition of truthful information.2. A computer programmer lobbies against copyrighting software. He argues that everyone should benefit from innovative programs written for personal computers and that exposure to a wide variety of computer programs will inspire young programmers to create even more innovative programs. Considering the marginal social benefits possibly gained by his proposal, do you agree with the programmer’s position?Computer software as information is a classic example of a public good. Since it can becostlessly copied, the marginal cost of providing software to an additional user is nearzero. Therefore, software is nonrival. (The fixed costs of creating software are high, butthe variable costs are low.) Furthermore, it is expensive to exclude consumers fromcopying and using software because copy protection schemes are available only at highcost or high inconvenience to users. Therefore, software is also nonexclusive. As bothnonrival and nonexclusive, computer software suffers the problems of public goodsprovision: the presence of free-riders makes it difficult or impossible for markets toprovide the efficient level of software. Rather than regulating this market directly, thelegal system guarantees property rights to the creators of software. If copyrightprotection were not enforced, it is likely that the software market would collapse.Therefore, we do not agree with the computer programmer.3. Four firms located at different points on a river dump various quantities of effluent into it. The effluent adversely affects the quality of swimming for homeowners who live downstream. These people can build swimming pools to avoid swimming in the river, and firms can purchase filters that eliminate harmful chemicals in the material that is dumped in the river. As a policy advisor for a regional planning organization, how would you compare and contrast the following options for dealing with the harmful effect of the effluent:a. An equal-rate effluent fee on firms located on the river.First, one needs to know the value to homeowners of swimming in the river. Thisinformation can be difficult to obtain, because homeowners will have an incentive tooverstate this value. As an upper boundary, if there are no considerations other thanswimming, one could use the cost of building swimming pools, either a pool for eachhomeowner or a public pool for all homeowners. Next, one needs to know the marginalcost of abatement. If the abatement technology is well understood, this informationshould be readily obtainable. If the abatement technology is not understood, anestimate based on the firms’ knowledge must be used.The choice of a policy tool will depend on the marginal benefits and costs of abatement.If firms are charged an equal-rate effluent fee, the firms will reduce effluents to thepoint where the marginal cost of abatement is equal to the fee. If this reduction is nothigh enough to permit swimming, the fee could be increased. Alternatively, revenuefrom the fees could be to provide swimming facilities, reducing the need for effluentreduction.b. An equal standard per firm on the level of effluent each firm can dump.Standards will be efficient only if the policy maker has complete information regardingthe marginal costs and benefits of abatement. Moreover, the standard will notencourage firms to reduce effluents further when new filtering technologies becomeavailable.c. A transferable effluent permit system, in which the aggregate level of effluent isfixed and all firms receive identical permits.A transferable effluent permit system requires the policy maker to determine theefficient effluent standard. Once the permits are distributed and a market develops,firms with a higher cost of abatement will purchase permits from firms with lowerabatement costs. However, unless permits are sold initially, rather than merelydistributed, no revenue will be generated for the regional organization.4. Recent social trends point to growing intolerance of smoking in public areas. Many people point out the negative effects of “second hand” smoke. If you are a smoker and you wish to continue smoking despite tougher anti smoking laws, describe the effect of the following legislative proposals on your behavior. As a result of these programs, do you, the individual smoker, benefit? Does society benefit as a whole?Since smoking in public areas is similar to polluting the air, the programs proposedhere are similar to those examined for air pollution. A bill to lower tar and nicotinelevels is similar to an emissions standard, and a tax on cigarettes is similar to anemissions fee. Requiring a smoking permit is similar to a system of emissions permits,assuming that the permits would not be transferable. The individual smoker in all ofthese programs is being forced to internalize the externality of “second-hand” smokeand will be worse off. Society will be better off if the benefits of a particular proposaloutweigh the cost of implementing that proposal. Unfortunately, the benefits ofreducing second-hand smoke are uncertain, and assessing those benefits is costly.a. A bill is proposed that would lower tar and nicotine levels in all cigarettes.The smoker will most likely try to maintain a constant level of consumption of nicotine,and will increase his or her consumption of cigarettes. Society may not benefit fromthis plan if the total amount of tar and nicotine released into the air is the same.b. A tax is levied on each pack of cigarettes sold.Smokers might turn to cigars, pipes, or might start rolling their own cigarettes. Theextent of the effect of a tax on cigarette consumption depends on the elasticity ofdemand for cigarettes. Again, it is questionable whether society will benefit.c. Smokers would be required to carry smoking permits at all times. These permitswould be sold by the government.Smoking permits would effectively transfer property rights to clean air from smokers tonon-smokers. The main obstacle to society benefiting from such a proposal would bethe high cost of enforcing a smoking permits system.5. A beekeeper lives adjacent to an apple orchard. The orchard owner benefits from thebees because each hive pollinates about one acre of apple trees. The orchard owner pays nothing for this service, however, because the bees come to the orchard without his having to do anything. There are not enough bees to pollinate the entire orchard, and the orchard owner must complete the pollination by artificial means, at a cost of $10 per acre of trees.Beekeeping has a marginal cost of MC = 10 + 2Q, where Q is the number of beehives.Each hive yields $20 worth of honey.a. How many beehives will the beekeeper maintain?The beekeeper maintains the number of hives that maximizes profits, when marginalrevenue is equal to marginal cost. With a constant marginal revenue of $20 (there is noinformation that would lead us to believe that the beekeeper has any market power)and a marginal cost of 10 + 2Q:20 = 10 + 2Q, or Q = 5.b. Is this the economically efficient number of hives?If there are too few bees to pollinate the orchard, the farmer must pay $10 per acre forartificial pollination. Thus, the farmer would be willing to pay up to $10 to thebeekeeper to maintain each additional hive. So, the marginal social benefit, MSB, ofeach additional hive is $30, which is greater than the marginal private benefit of $20.Assuming that the private marginal cost is equal to the social marginal cost, we setMSB = MC to determine the efficient number of hives:30 = 10 + 2Q, or Q = 10.Therefore, the beekeeper’s private choice of Q = 5 is not the socially efficient number ofhives.c. What changes would lead to the more efficient operation?The most radical change that would lead to more efficient operations would be themerger of the farmer’s business with the beekeeper’s business. This merger wouldinternalize the positive externality of bee pollination. Short of a merger, the farmerand beekeeper should enter into a contract for pollination services.7. Reconsider the common resource problem as given by Example 18.5. Suppose that crawfish popularity continues to increase, and that the demand curve shifts from C = 0.401 - 0.0064F to C = 0.50 - 0.0064F. How does this shift in demand affect the actual crawfish catch, the efficient catch, and the social cost of common access? (Hint: Use the marginal social cost and private cost curves given in the example.)The relevant information is now the following:Demand: C = 0.50 - 0.0064FMSC: C = -5.645 + 0.6509F.With an increase in demand, the demand curve for crawfish shifts upward, intersectingthe price axis at $0.50. The private cost curve has a positive slope, so additional effortmust be made to increase the catch. Since the social cost curve has a positive slope, thesocially efficient catch also increases. We may determine the socially efficient catch bysolving the following two equations simultaneously:0.50 - 0.0064F = -5.645 + 0.6509F, or F* = 9.35.To determine the price that consumers are willing to pay for this quantity, substituteF* into the equation for marginal social cost and solve for C:C = -5.645 + (0.6509)(9.35), or C = $0.44.Next, find the actual level of production by solving these equations simultaneously:Demand: C = 0.50 - 0.0064FMPC: C = -0.357 + 0.0573F0.50 - 0.0064F = -0.357 + 0.0573F, or F** = 13.45.To determine the price that consumers are willing to pay for this quantity, substituteF** into the equation for marginal private cost and solve for C:C = -0.357 + (0.0573)(13.45), or C = $0.41.Notice that the marginal social cost of producing 13.45 units isMSC = -5.645 +(0.6509)(13.45) = $3.11.With the increase in demand, the social cost is the area of a triangle with a base of 4.1million pounds (13.45 - 9.35) and a height of $2.70 ($3.11 - 0.41), or $5,535,000 morethan the social cost of the original demand.8. The Georges Bank, a highly productive fishing area off New England, can be divided into two zones in terms of fish population. Zone 1 has the higher population per square mile but is subject to severe diminishing returns to fishing effort. The daily fish catch (in tons) in Zone 1 isF 1 = 200(X1) - 2(X1) 2where X1is the number of boats fishing there. Zone 2 has fewer fish per mile but is larger, and diminishing returns are less of a problem. Its daily fish catch isF 2 = 100(X2) - (X2) 2where X2is the number of boats fishing in Zone 2. The marginal fish catch MFC in each zone can be represented asMFC1 = 200 - 4(X1) MFC2= 100 - 2(X2).There are 100 boats now licensed by the U.S. government to fish in these two zones. The fish are sold at $100 per ton. The total cost (capital and operating) per boat is constant at $1,000 per day. Answer the following questions about this situation.a. If the boats are allowed to fish where they want, with no government restriction,how many will fish in each zone? What will be the gross value of the catch?Without restrictions, the boats will divide themselves so that the average catch (AF 1and AF 2) for each boat is equal in each zone. (If the average catch in one zone is greaterthan in the other, boats will leave the zone with the lower catch for the zone with thehigher catch.) We solve the following set of equations:AF 1 = AF 2 and X 1 + X 2 = 100 where 11121120022002AF X X X X =-=- and 222222100100AF X X X X =-=-. Therefore, AF 1 = AF 2 implies200 - 2X 1 = 100 - X 2,200 - 2(100 - X 2) = 100 - X 2, or X 21003= and 320031001001=⎪⎭⎫ ⎝⎛-=X . Find the gross catch by substituting the value of X 1 and X 2 into the catch equations:()(),,,,F 444488983331332002320020021=-=⎪⎭⎫ ⎝⎛-⎪⎭⎫ ⎝⎛= and ().,,,F 2222111133333100310010022=-=⎪⎭⎫ ⎝⎛-⎪⎭⎫ ⎝⎛= The total catch is F 1 + F 2 = 6,666. At the price of $100 per ton, the value of the catch is$666,600. The average catch for each of the 100 boats in the fishing fleet is 66.66 tons.To determine the profit per boat, subtract total cost from total revenue:π = (100)(66.66) - 1,000, or π = $5,666.Total profit for the fleet is $566,000.b. If the U.S. government can restrict the boats, how many should be allocated to eachzone? What will the gross value of the catch be? Assume the total number of boats remains at 100.Assume that the government wishes to maximize the net social value of the fish catch,i.e., the difference between the total social benefit and the total social cost. Thegovernment equates the marginal fish catch in both zones, subject to the restrictionthat the number of boats equals 100:MFC 1 = MFC 2 and X 1 + X 2 = 100,MFC 1 = 200 - 4X 1 and MFC 2 = 100 - 2X 2.Setting MFC 1 = MFC 2 implies:200 - 4X 1 = 100 - 2X 2, or 200 - 4(100 - X 2) = 100 - 2X 2, or X 2 = 50 andX 1 = 100 - 50 = 50.Find the gross catch by substituting X 1 and X 2 into the catch equations:F 1 = (200)(50) - (2)(502) = 10,000 - 5,000 = 5,000 andChapter 18: Externalities and Public Goods242 F 2 = (100)(50) - 502 = 5,000 - 2,500 = 2,500.The total catch is equal to F 1 + F 2 = 7,500. At the market price of $100 per ton, thevalue of the catch is $750,000. Total profit is $650,000. Notice that the profits are notevenly divided between boats in the two zones. The average catch in Zone A is 100 tonsper boat, while the average catch in Zone B is 50 tons per boat. Therefore, fishing inZone A yields a higher profit for the individual owner of the boat.c. If additional fishermen want to buy boats and join the fishing fleet, should agovernment wishing to maximize the net value of the fish catch grant them licenses to do so? Why or why not?To answer this question, first determine the profit-maximizing number of boats in eachzone. Profits in Zone A areππA A X X X X X =--=-1002002100019000200112112b g e j,,, or . To determine the change in profit with a change in X 1 take the first derivative of theprofit function with respect to X 1:d dX X A π1119000400=-,. To determine the profit-maximizing level of output, setd dX A π1equal to zero and solve for X 1:19,000 - 400X 1 = 0, or X 1 = 47.5.Substituting X 1 into the profit equation for Zone A gives: ()()()()()()()()250,451$5.47000,15.4725.472001002=--=A π.For Zone B follow a similar procedure. Profits in Zone B areππB B X X X X X =--=-100100100090002002222222b g e j,,, or . Taking the derivative of the profit function with respect to X 2 givesd X B π229000200=-,. Setting d B π2equal to zero to find the profit-maximizing level of output gives 9,000 - 200X 2 = 0, or X 2 = 45.Substituting X 2 into the profit equation for Zone B gives:πB = (100)((100)(45) - 452) - (1,000)(45) = $202,500.Total profit from both zones is $653,750, with 47.5 boats in Zone A and 45 boats in ZoneB. Because each additional boat above 92.5 decreases total profit, the governmentshould not grant any more licenses.。
平新乔微观经济学第18讲
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（张五常 佃农理论 商务印书馆 第三章）
而事实上，当以上的每项契约的达成都是需要交易成本的，比如商定和执行合约条款 的费用、对条款中的数值标准的测定、以及双方在商定之前收集信息所需要的费用、在合 约中的产权的全部或者是部分转让、以及在生产中各种投入要素的相互协调所要的花费成 本等等；
3、生产总成本为企业所有员工（人数×每人工资）的工资与每单位产量的平均成本：
18-10-6 12/13/2005 9:48:54 PM
第十八讲 企业的性质、边界与产权
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平狄克《微观经济学》第9版笔记和课后习题详解(外部性与公共物品)【圣才出品】
平狄克《微观经济学》第9版笔记和课后习题详解第18章外部性与公共物品18.1复习笔记【知识框架】【考点难点归纳】考点一：外部性★★★外部性是指一个经济主体的经济活动对他人和社会造成的非市场化影响，这种影响既可以是正向也可以是负向。
当某个经济主体的行为使他人或社会受益，而受益者无须付出任何代价时，称之为正的外部性；当某个经济主体的行为使他人或社会受损，而行为主体却无须为此承担成本时，称之为负的外部性。
由于外部性并不反应在市场价格中，因此可能会导致经济无效率和市场失灵。
1．负的外部性和无效率当存在负的外部性时，边际社会成本（MSC）大于边际私人成本（MC），差额就是边际外部成本（MEC）。
从社会的角度看，由于厂商未能将与负外部性伴随的成本纳入考虑，导致生产过剩。
有效产出水平应当是价格等于生产的边际社会成本。
外部性既导致短期也导致长期的无效率。
厂商通过对比产品价格和生产的平均成本来决定是否进入行业：价格高于成本，厂商就进入；价格低于成本，厂商就退出。
在长期均衡中，价格等于（长期）平均成本。
当存在负的外部性时，平均私人生产成本低于平均社会成本，厂商判断产品价格高于其生产的成本即平均私人成本，选择留在产业内，但对社会而言是无效率的。
2．正的外部性和无效率当存在正的外部性时，边际社会收益（MSB）大于边际私人收益（D），差额就是边际外部收益（MEB），即MSB＝D＋MEB。
有效产出水平处于MSB和MC曲线的相交处。
正的外部性也会导致无效率。
一个正的外部性导致无效率的例子就是厂商在研究与开发上所花费的钱，研究带来的创新常常难以受到保护而被别的厂商得到，研发投资得不到回报就无法再获得资金支持。
考点二：纠正市场失灵的办法★★★污染是外部性导致市场失灵的一般例子，可以通过排污标准、排污费、可转让排污许可证或者通过鼓励再生利用得到纠正。
在成本和收益都存在不确定性时，这些机制的选择，取决于边际社会成本和边际收益曲线的形状。
微观经济学十八讲答案
微观经济学十八讲答案【篇一：平新乔《微观经济学十八讲》课后习题详解(第13讲委托—代理理论初步)】t>经济学考研交流群点击加入平新乔《微观经济学十八讲》第13讲委托—代理理论初步跨考网独家整理最全经济学考研真题，经济学考研课后习题解析资料库，您可以在这里查阅历年经济学考研真题，经济学考研课后习题，经济学考研参考书等内容，更有跨考考研历年辅导的经济学学哥学姐的经济学考研经验，从前辈中获得的经验对初学者来说是宝贵的财富，这或许能帮你少走弯路，躲开一些陷阱。
以下内容为跨考网独家整理，如您还需更多考研资料，可选择经济学一对一在线咨询进行咨询。
1．一家厂商的短期收益由r?10e?e2x给出，其中e为一个典型工人（所有工人都假设为是完全一样的）的努力水平。
工人选择他减去努力以后的净工资w?e（努力的边际成本假设为1）最大化的努力水平。
根据下列每种工资安排，确定努力水平和利润水平（收入减去支付的工资）。
解释为什么这些不同的委托—代理关系产生不同的结果。
（1）对于e?1，w?2；否则w?0。
（2）w?r/2。
（3）w?r?12.5。
解：（1）对于e?1，w?2；否则w?0，此时工人的净工资为：?2?ee?1w?e???ee?1?所以e*?1时，工人的净工资最大。
雇主利润为：?*?r?w?10e?e2x?2?10?x?2?8?x工人的净工资线如图13-1所示。
图13-1 代理人的净工资最大化（2）当w?r/2时，工人的净工资函数为：11w?e?5e?e2x?e??e2x?4e22净工资最大化的一阶条件为：d?w?e?de??ex?4?0解得：e??4。
x?2111?4?4??12雇主利润??r?r?r??10?????x??。
222?x?x????xborn to win经济学考研交流群点击加入（3）当w?r?12.5时，工人的净工资函数为：w?e?10e?e2x?12.5?e??e2x?9e?12.5净工资最大化的一阶条件为：d?w?e?de??2ex?9?0解得：e??4.5。
平狄克微观经济学答案——第18章 外部性和公共产品
第十八章外部性和公共产品1．在居民住宅占据了城镇的东部之后，几家工厂设立在西部。
每家厂商生产相同的产品，并且在生产中排放有害气体，对社区的居民产生不利的影响。
（1）为什么厂商生产会产生外部性？工厂产生的有害气体会影响居民的效用函数，而且居民不能控制气体的量。
我们可以认为有害气体会减少居民的效用（即负的外部性），降低房地产的价值。
（2）你认为私下讨价还价会解决这一外部性问题吗？请解释。
如果居民预计到工厂的设立，那么房屋价格会反映出有害气体造成的效用低下；通过房屋市场的价格调节使外部性内部化。
如果预计到有害气体，只有当存在数量较少的团体（企业或家庭）且产权界定清晰时，私下的讨价还价才能解决外部性的问题。
私下的讨价还价取决于每个家庭为空气质量支付的意愿，但是真实的信息披露几乎不可能。
工厂已有的生产技术的转化以及工厂和家庭之间的雇佣关系都会使这个问题更加复杂。
私下的讨价还价不大可能解决这个问题。
（3）社区可能会怎样决定空气质量的有效水平?社区可以通过把家庭的支付意愿相加并使其等于减少污染的边际成本来求出空气质量的经济效率水平。
这两步都要求获得真实的信息。
2．一个电脑编程人员游说反对对软件进行版权保护。
他的论点是，每个人都应当从为个人电脑编写的创新程序中获益，，与各种各样电脑程序的接触甚至会鼓舞年轻的编程人员编出更多的创新程序。
考虑到由于它的建议而可能得到的边际社会收益，你同意该编程人员的主张吗？信息中给出的计算机软件是一个经典的公共产品的例子。
因为它可以无成本的复制，所以向一个额外的消费者提供软件的边际成本几乎为零。
所以软件是非竞争性的。
（编写软件的固定成本很高，但可变成本却很低。
）另外，防止消费者复制和使用软件的代价很高，因为只有付出很高的成本或给消费者带来很大不便才能保护版权。
所以，软件也是非排他性的。
由于具有非竞争性和非排他性，计算机软件面临着公共产品：免费搭车者的存在使得市场很难或不可能提供有效率的软件水平。
平新乔十八讲课后习题答案
1-6-1
第一讲 偏好、效用与消费者的基本问题
让我们首先来看一个例子，而在例子结束时，也就是我们回答此问题结束之际；
假设生产 a 单位的产出要固定用用上 a1 单位的 x1 与 a2 单位的 x2 ，那么此技术的生产函
越靠上的曲线所代表的效用水平就越高。
(3)
Y
y =−2 x3
Y
y = 2x
X
对于李楠而言汽水 x 与冰棍 y 是完全替代 的；三杯汽水 x 与两根冰棍 y 所带来的效用水
平是一样的，她的效用曲线拥有负的斜率；对
于一定量的汽水 x 而言，越多的冰棍 y 越好，
所以越靠上的曲线所代表的效用水平就越高；
她效用函数可用 u(x, y) = 3x + 2 y 表示。
ψ (x,λ) = x1 + λ(m − p1x1 − p2x2 )
∂ψ ∂x1
= 1 − λp1
=0
∂ψ ∂x2
= −λp2
=0
∂ψ ∂λ
=m−
p1x1 −
p2 x2
=0
由上式可得马歇尔需求函数： x1
=
m p1
； x2
=0
10
max = u(x)
x
s.t. m = p1x1 + p2x2
构造拉氏方程： ψ (x, λ) = Ax1α x12−α + λ(m − p1x1 − p2x2 )
∂ψ ∂x1
= 20(x1 +
x2 ) − λp1
=0
∂ψ ∂x2
=
20( x1
平狄克《微观经济学》(第7版)习题详解(第18章 外部性与公共品)
平狄克《微观经济学》（第7版）第18章外部性与公共品课后复习题详解跨考网独家整理最全经济学考研真题，经济学考研课后习题解析资料库，您可以在这里查阅历年经济学考研真题，经济学考研课后习题，经济学考研参考书等内容，更有跨考考研历年辅导的经济学学哥学姐的经济学考研经验，从前辈中获得的经验对初学者来说是宝贵的财富，这或许能帮你少走弯路，躲开一些陷阱。
以下内容为跨考网独家整理，如您还需更多考研资料，可选择经济学一对一在线咨询进行咨询。
1．下列哪个描述了外部性，哪个没有？解释它们的区别。
（1）巴西限制咖啡出口的政策导致美国咖啡的价格上升，它反过来又导致茶叶的价格上升。
（2）一则广告传单使一个驾驶汽车的人分心，结果使他撞上一根电线杆。
答：（1）巴西限制咖啡出口的政策没有外部性。
巴西限制咖啡出口的政策导致美国咖啡的价格上升，是因为美国所面临的咖啡的供给减少了。
因为咖啡的价格提高，所以消费者转向咖啡的替代品茶，从而使得茶的需求增加，因此导致茶叶价格的上升。
这是市场的作用，而不是外部性。
（2）广告传单有外部性。
广告传单通过宣传某些产品或服务而传达信息。
但是，它传达这些信息的方式可能会使驾驶汽车的人分心，对那些在电线杆附近的驾驶者就可能会造成事故。
因为广告公司索取的广告费中并不包含使驾驶者分心的外部性的成本，传单对驾驶者产生了危害他们安全的负的外部性。
两者的区别在于：巴西的这项政策对美国产生的影响并没有造成其私人成本和社会成本之间，或其私人收益和社会收益之间的不一致，所以没有外部性；而广告传单对它所处的经济环境产生负面影响，所以具有外部性。
2．在减污的成本和收益不确定时，比较和对照下列三种对付污染外部性的机制：（a）排污费；（b）排污标准；（c）可转让排污许可证制度。
答：（1）三种机制的含义排污费是对厂商每单位污染物的收费。
征收一定的排污费将产生有效率的行为。
排污标准是对厂商可以排放多少污染物的法定限制。
如果厂商超过限制，它就会面临经济惩罚甚至刑事惩罚。
最新平狄克微观经济学答案第17-18章
平狄克微观经济学答案第17－18章第十七章复习题1、当买方和卖方之间对商品存在着不对称信息时，即当不同质量的产品的购买者或出售者买卖时没有充分的信息来确定产品的质量，从而不同质量的产品以单一价格出售，逆淘汰问题就出现了，结果市场就有太多的低质量产品和太少的高质量产品出售，低质量产品把高质量的产品逐出了市场，导致市场失灵。
2、多。
3、保险市场的逆淘汰：由于信息的不对称，即使保险公司做身体检查，购买保险的人对他们总的健康情况也比任何保险公司所希望知道不健康的人在被保险人总数中的比例提高了。
这迫使价格上升，从而使那些较健康的人，由于知道自己的低风险，作出不投保决定，这进一步提高了不健康的人的比例，这又迫使保险价格上升，如此等等，直到几乎所有买保险的人都是不健康的人。
保险市场的道德风险：当被保险一方充分保险，而一家信息有限的保险公司又不能准确的监督他的话，被保险方可能采取会提高事故或受伤可能性的行动，当被保险方能影响导致赔偿的事件的可能性或程度时，道德风险就会发生。
4、保证和保证书、产品标准化、保证和保证书5、当不同质量的产品在购买者或出售者买卖时没有充分的住处来确定产品的真实质量，从而不同质量的产品以单一价格出售时，逆淘汰问题就出现了。
存在的根本原因是信息不对称，即买主对产品质量的住处知道的比卖主少的多，如果卖主能发出有关产品的信息，就会消除信息不对称，避免逆淘汰问题的发生，对高质量的产品而言当然是有利的。
保证和保证书有效地发出了产品质量信号，因为一项内容广泛的保证书对低质量的产品的生产者来说要比高质量产品的生产者成本更高（在保证书下，低质量产品更需要修理服务，而这都将由生产者支付）。
结果，出于他们的利益，低质量产品的生产者就不会提供内容广泛的保证书。
消费者就能因此而把一项社会主义少保证书看作是高质量的信号屏为提供保证书的商品支付较多的钱。
6、因为大多数企业业主并不能监督总经理所作的一切，总经理的住处比业主多的多，这种信息的不对称，产生委托——代理问题，即，经理可以追求他们的自己的目标，甚至不惜以获得较低利润为代价。
微观经济学-第十二章-外部性与公共产品-习题
第十二章外部性与公共产品一、重点和难点（一）重点1．外部性的机理与解决思路2．效率改进方法（二）难点1．公共产品的供求问题以及相应的决策规则二、关键概念外部性交易成本科斯定理公共物品免费搭车一致同意规则三、习题（一）单项选择题1．可用（）来描述一个养蜂主与邻近的经营果园的农场主之间的影响。
A．外部不经济B．外部经济C．外部损害D．以上都不对2．某人的吸烟行为属于（）。
A．生产的外部经济B．消费的外部不经济C．生产的外部不经济D．消费的外部经济3．如果上游工厂污染了下游居民的饮水，按照科斯定理，（），问题可妥善解决。
A．不管产权是否明确，只要交易成本为零B．不论产权是否明确，交易成本是否为零C．只要产权明确，且交易成本为零D．只要产权明确，不管交易成本有多大4．解决外部不经济可采取（）。
A．征税的方法B．通过产权界定的方法C．通过将外部性内在化的方法D．以上各项均可5．“搭便车”现象是对下面哪个问题的一种形象的描述？（）A．社会福利问题 B.公共选择问题 C.公共产品问题 D.市场失灵问题6．某一活动存在外部经济是指该活动的（）。
A．私人利益大于社会利益B．私人成本小于社会成本C．私人利益小于社会利益D．私人成本大于社会成本7．政府进行市场干预的理由在于（）。
A．税收B．反托拉斯法C．外部性D．以上都是8．以下（）不是公共产品的特征。
A．非排他性 B.竞争性 C.外部性 D.由政府提供9．（）最准确地说明了产生污染的生产是缺乏效率的。
A．社会总成本高于私人成本B．社会边际成本高于私人边际成本C．产量大于社会最优产量D．忽略了外在成本10．公共产品的定价（）。
A．由市场供求决定B．由垄断组织通过竞争决定C．用成本――效益分析法进行评估D．由购买者决定11．公共产品的需求曲线是消费者个人需求曲线的（）。
A．垂直相加B．水平相加C．算术平均数D．加权平均数12．公共产品的生产可通过特定的社会体制决定，称为公共选择理论，下面属于公共选择理论的内容为（）。
平狄克《微观经济学》(第7版)课后习题详解 第18章 外部性与公共品【圣才出品】
第18章外部性与公共品18.1课后复习题详解1．下列哪个描述了外部性，哪个没有？解释它们的区别。
（1）巴西限制咖啡出口的政策导致美国咖啡的价格上升，它反过来又导致茶叶的价格上升。
（2）一则广告传单使一个驾驶汽车的人分心，结果使他撞上一根电线杆。
答：（1）巴西限制咖啡出口的政策没有外部性。
巴西限制咖啡出口的政策导致美国咖啡的价格上升，是因为美国所面临的咖啡的供给减少了。
因为咖啡的价格提高，所以消费者转向咖啡的替代品茶，从而使得茶的需求增加，因此导致茶叶价格的上升。
这是市场的作用，而不是外部性。
（2）广告传单有外部性。
广告传单通过宣传某些产品或服务而传达信息。
但是，它传达这些信息的方式可能会使驾驶汽车的人分心，对那些在电线杆附近的驾驶者就可能会造成事故。
因为广告公司索取的广告费中并不包含使驾驶者分心的外部性的成本，传单对驾驶者产生了危害他们安全的负的外部性。
两者的区别在于：巴西的这项政策对美国产生的影响并没有造成其私人成本和社会成本之间，或其私人收益和社会收益之间的不一致，所以没有外部性；而广告传单对它所处的经济环境产生负面影响，所以具有外部性。
2．在减污的成本和收益不确定时，比较和对照下列三种对付污染外部性的机制：（a）排污费；（b）排污标准；（c）可转让排污许可证制度。
答：（1）三种机制的含义排污费是对厂商每单位污染物的收费。
征收一定的排污费将产生有效率的行为。
排污标准是对厂商可以排放多少污染物的法定限制。
如果厂商超过限制，它就会面临经济惩罚甚至刑事惩罚。
可转让排污许可证是一种可以产生数量一定且有限的污染的许可证，它分配在各个厂商之间并且可以在它们之间进行买卖。
（2）排污费和排污标准的比较①某一点的有效排放水平可以通过排污费或者排污标准来实现。
如图18-1所示，*E点的有效排污水平可以通过排污费或者排污标准来实现。
当面临每单位排放3美元的费时，厂商减少排放直至排污费等于边际收益那一点。
同样水平的排放削减可以用标准将排放限制在12单位来实现。
平新乔《微观经济学十八讲》课后习题和强化习题详解(1-3讲)【圣才出品】
lim
→0
1
x1 ln x1 1 x1
+ +
2 2
x2 x2
ln
x2
= exp
1 ln x1 +
2 ln x2
=
x1 1
x2 2
1 + 2 = 1
1
( ) （3）当 → − 时，对效用函数 u( x1, x2 ) = 1x1 + 2 x2 两边变换求极限有：
( ) ( ) lim u
3 / 62
4．设
u
(
x1,
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)
=
1 2
ln
x1
+
1 2
ln
x2
，这里
x1，x2
R+
。
（1）证明： x1 与 x2 的边际效用都递减。
（2）请给出一个效用函数形式，但该形式不具备边际效用递减的性质。
答：（1）将 u
关于
x1
和
x2
分别求二阶偏导数得
2u x12
=
−
1 2x12
y)
=
min
x,
y 2
，如图
1-3
所示。
图 1-3 喝一杯汽水就要吃两根冰棍 （4）如图 1-4 所示，其中 x 为中性品。
图 1-4 对于有无汽水喝毫不在意
2．作图：如果一个人的效用函数为 u ( x1, x2 ) = maxx1, x2
2 / 62
（1）请画出三条无差异曲线。 （2）如果 p1 = 1 ， p2 = 2 ， y = 10 。请在图 1-5 上找出该消费者的最优消费组合。 答：（1）由效用函数画出的三条无差异曲线如图 1-5 所示。
平新乔微观经济学十八讲》答案
5.1. 当 ρ = 1 ，该效用函数为线性．
证明：当 ρ = 1 时，效用函数为
u(x1, x2 ) = α1x1 + α 2 x2 此时，函数 u 是线性的．
4
第一讲 偏好、效用……
5.2.
当ρ
→
0 时，该效用函数趋近于 u(x1 ,
x2 )
=
x α1 1
x α2 2
β1
证明：令
=
α1 α1 + α2
2 x12
因此 x1 的边际效用是递减的．同理， x2 的边际效用也是递减的．i
4.2. 请给出一个效用函数形式，使该形式不具备边际效用递减的性质．
答：可能的一个效用函数是 u(x1, x2 ) = x1 + x2 ．
5. 常见的常替代弹性效用函数形式为
请证明：
( )1
u(x1 , x2 ) = α1 x1ρ + α 2 x2 ρ ρ
述的偏好中，商品 1 与商品 2 是完全替代的．
4. 若某个消费者的效用函数为
u ( x1 ,
x2 )
=
1 2
ln
x1
+
1 2
ln
x2
其中， x1, x2 ∈ R+
4.1. 证明： x1 与 x2 的边际效用都递减．
证明： u(x1, x2 ) 对 x1 取二阶偏导：
∂2u = − 1 < 0
∂x12
不具有完备性．同理可以说明无差异关系也不具有完备性．
8.2. ≈ 满足反身性
说明：如果无差异关系不具有完备性，那么根据无差异关系的定义，则必存在一个消
费束严格偏好于它自身，也就是说，这个消费束同时既偏好于它本身又不偏好于它本
(NEW)平狄克《微观经济学》(第7、8版)章节习题精编详解
目 录第1篇 导论：市场和价格第1章 绪 论第2章 供给和需求的基本原理第2篇 生产者、消费者与竞争性市场第3章 消费者行为第4章 个人需求和市场需求第5章 不确定性与消费者行为第6章 生 产第7章 生产成本第8章 利润最大化与竞争性供给第9章 竞争性市场分析第3篇 市场结构与竞争策略第10章 市场势力：垄断和买方垄断第11章 有市场势力的定价第12章 垄断竞争和寡头垄断第13章 博弈论与竞争策略第14章 投入要素市场第15章 投资、时间与资本市场第4篇 信息、市场失灵与政府的角色第16章 一般均衡与经济效率第17章 信息不对称的市场第18章 外部性和公共物品附 录 指定平狄克《微观经济学》教材为考研参考书目的院校列表第1篇 导论：市场和价格第1章 绪 论一、单项选择题1．经济学可以被定义为（ ）。
A ．政府对市场制度的干预B ．企业赚取利润的活动C ．研究稀缺资源如何有效配置的问题D ．个人的生财之道2．经济物品是指（ ）。
A ．有用的东西B ．稀缺的物品C ．要用钱购买的物品D ．有用且稀缺的物品C【答案】经济学是研究人们和社会如何做出选择，来使用可以有其他用途的稀缺的经济资源在现在或是将来生产各种物品，并把物品分配给社会的各个成员或集团以供消费之用的一门社会科学。
【解析】D【答案】现实世界中绝大多数的物品都是不能自由取得的，因为资【解析】3．一个经济体必须作出的基本选择是（ ）。
A ．生产什么B ．生产多少，何时生产C ．为谁生产D ．以上都是4．宏观经济学与微观经济学的关系是（ ）。
A ．相互独立的B ．两者建立在共同的理论基础上C ．两者既有联系又有矛盾D ．毫无联系源是稀缺的，要获得这些有限的物品就必须付出代价，这种物品就被称为“经济物品”。
D【答案】经济学所要解决的问题包括：①生产什么；②如何生产；③为谁生产；④何时生产。
【解析】C【答案】宏观经济学所研究的总量经济特征正是由经济体系中无数微观主体（家庭和厂商）的经济行为所决定的，因而微观经济主体的决策行为就构成了宏观经济分析的基础，宏观经济学需要构建自己的微观基础。
平新乔课后习题详解(第17讲--外在性、科斯定理与公共品理论)
平新乔《微观经济学十八讲》第17讲 外在性、科斯定理与公共品理论1．假定一垄断者产生了损害性的外部效应。
请使用消费者剩余的概念去分析对污染者的一个最优税收是否对于改善福利是必需的。
答：征税对于改善福利不是必需的。
征税意味着提高垄断者的边际成本，根据成本加成定价原则，产品的价格也会上升，同时销售量减少，所以消费者的福利和社会福利总额都减少。
如图17-1所示，征税后，边际成本曲线由MC 上升到T MC ，从而使厂商在征税后的边际成本等于其实际的社会边际成本，根据边际成本加成定价原则，垄断价格从C 上升到B ，市场需求从F 下降到G ，社会总剩余从AEMK S 减少到ADHK S ，征税后的社会福利状况恶化。
图17-1 征税引起社会福利恶化2．在一个完全竞争行业中的一家厂商首创了一种制作小机械品的新过程。
新过程使厂商的平均成本曲线下移，这意味着这家厂商自己（尽管仍是一个价格接受者）能在长期获得真正的经济利润。
（1）如果每件小机械品的市场价格是20美元，厂商的边际成本曲线为0.4MC q =，其中q 是厂商每日的小机械品产量，厂商将生产多少小机械品？（2）假定政府的研究发现厂商的新过程污染空气，并且估计厂商生产小机械品的社会边际成本是0.5SMC q =。
如果市场价格仍为20美元，什么是厂商在社会上的最优生产水平？为了实现这种最优生产水平，政府应征收多大比率的税收？（3）用图形表示你的结果。
解：（1）对该竞争性厂商而言，其最优产量决策应当满足P MC =，即200.4q =，解得50q =。
故如果每件小机械品的市场价格为20美元，厂商将生产50件小机械品。
（2）从政府的角度讲，厂商的最优产量决策应当满足P SM C =，即200.5q =，解得40q =。
为了使厂商生产全社会有效水平的产量40q =，政府应当对厂商征税。
假设征收从量税税率为t ，则征税后厂商的边际成本为()0.4MC t q t =+，那么厂商的最优产量决策满足：0.4P q t =+ ①把20P =和40q =代入①式中，解得4t =。
微观经济学-第十二章-外部性与公共产品-习题
第十二章外部性与公共产品一、重点和难点（一）重点1．外部性的机理与解决思路2．效率改进方法（二）难点1．公共产品的供求问题以及相应的决策规则二、关键概念外部性交易成本科斯定理公共物品免费搭车一致同意规则三、习题（一）单项选择题1．可用（）来描述一个养蜂主与邻近的经营果园的农场主之间的影响。
A．外部不经济B．外部经济C．外部损害D．以上都不对2．某人的吸烟行为属于（）。
A．生产的外部经济 B．消费的外部不经济C．生产的外部不经济 D．消费的外部经济3．如果上游工厂污染了下游居民的饮水，按照科斯定理，（），问题可妥善解决。
A．不管产权是否明确，只要交易成本为零B．不论产权是否明确，交易成本是否为零C．只要产权明确，且交易成本为零D．只要产权明确，不管交易成本有多大4．解决外部不经济可采取（）。
A．征税的方法B．通过产权界定的方法C．通过将外部性内在化的方法D．以上各项均可5．“搭便车”现象是对下面哪个问题的一种形象的描述？（）A．社会福利问题 B.公共选择问题 C.公共产品问题 D.市场失灵问题6．某一活动存在外部经济是指该活动的（）。
A．私人利益大于社会利益B．私人成本小于社会成本C．私人利益小于社会利益D．私人成本大于社会成本7．政府进行市场干预的理由在于（）。
A．税收B．反托拉斯法C．外部性D．以上都是8．以下（）不是公共产品的特征。
A．非排他性 B.竞争性 C.外部性 D.由政府提供9．（）最准确地说明了产生污染的生产是缺乏效率的。
A．社会总成本高于私人成本B．社会边际成本高于私人边际成本C．产量大于社会最优产量D．忽略了外在成本10．公共产品的定价（）。
A．由市场供求决定B ．由垄断组织通过竞争决定C ．用成本――效益分析法进行评估D ．由购买者决定11．公共产品的需求曲线是消费者个人需求曲线的（ ）。
A ．垂直相加B ．水平相加C ．算术平均数D ．加权平均数12．公共产品的生产可通过特定的社会体制决定，称为公共选择理论，下面属于公共选择理论的内容为（ ）。
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平新乔《微观经济学十八讲》第17讲 外在性、科斯定理与公共品理论 跨考网独家整理最全经济学考研真题，经济学考研课后习题解析资料库，您可以在这里查阅历年经济学考研真题，经济学考研课后习题，经济学考研参考书等内容，更有跨考考研历年辅导的经济学学哥学姐的经济学考研经验，从前辈中获得的经验对初学者来说是宝贵的财富，这或许能帮你少走弯路，躲开一些陷阱。
以下内容为跨考网独家整理，如您还需更多考研资料，可选择经济学一对一在线咨询进行咨询。
1．假定一垄断者产生了损害性的外部效应。
请使用消费者剩余的概念去分析对污染者的一个最优税收是否对于改善福利是必需的。
答：征税对于改善福利不是必需的。
征税意味着提高垄断者的边际成本，根据成本加成定价原则，产品的价格也会上升，同时销售量减少，所以消费者的福利和社会福利总额都减少。
如图17-1所示，征税后，边际成本曲线由MC 上升到T MC ，从而使厂商在征税后的边际成本等于其实际的社会边际成本，根据边际成本加成定价原则，垄断价格从C 上升到B ，市场需求从F 下降到G ，社会总剩余从AEMK S 减少到ADHK S ，征税后的社会福利状况恶化。
图17-1 征税引起社会福利恶化2．在一个完全竞争行业中的一家厂商首创了一种制作小机械品的新过程。
新过程使厂商的平均成本曲线下移，这意味着这家厂商自己（尽管仍是一个价格接受者）能在长期获得真正的经济利润。
（1）如果每件小机械品的市场价格是20美元，厂商的边际成本曲线为0.4MC q =，其中q 是厂商每日的小机械品产量，厂商将生产多少小机械品？（2）假定政府的研究发现厂商的新过程污染空气，并且估计厂商生产小机械品的社会边际成本是0.5SMC q =。
如果市场价格仍为20美元，什么是厂商在社会上的最优生产水平？为了实现这种最优生产水平，政府应征收多大比率的税收？（3）用图形表示你的结果。
解：（1）对该竞争性厂商而言，其最优产量决策应当满足P MC =，即200.4q =，解得50q =。
故如果每件小机械品的市场价格为20美元，厂商将生产50件小机械品。
（2）从政府的角度讲，厂商的最优产量决策应当满足P SMC =，即200.5q =，解得40q =。
为了使厂商生产全社会有效水平的产量40q =，政府应当对厂商征税。
假设征收从量税税率为t ，则征税后厂商的边际成本为()0.4MC t q t =+，那么厂商的最优产量决策满足： 0.4P q t =+ ①把20P =和40q =代入①式中，解得4t =。
若以从价税来表示，则有：()0.4P MC t q ==+将价格20和产量40代入得到：0.1t =（3）（1）和（2）中的结果可如图17-2所示。
图17-2 通过征税限制污染量3．判断下述命题是否正确，并说明你的理由：（1）当存在外部效应时福利经济学第一定理不一定成立。
（2）“公共物品的提供，如果没有政府出钱或者出面组织，是不可能实现帕累托最优的。
”答：（1）正确。
福利经济学第一定理是说任何的竞争性均衡都是帕累托有效的，但此定理至少有以下三个暗含的假设条件：①消费者只关心本人的商品消费，而不顾他人，即不存在外部效应。
②每个交易者确实在进行竞争。
③只有竞争均衡确实存在时，第一定理才有其意义。
由此可知，当存在外在性时，福利经济学第一定理可能就不再成立。
（2）正确。
因为公共物品如果由私人提供，由于搭便车现象的存在，公共品的实际供给量可能会大大低于社会最优水平，从而不可能实现帕累托最优，这时就需要政府出钱或出面组织，直接提供有效数量的公共品。
从交易成本的角度讲，由于单个人之间的谈判存在很高的交易成本，彼此之间很难达成一致，因此交易成本相当高，很难在单个的个人之间达成一致，因此，由政府出面来组织公共品的提供，必然会比私人提供的数量更多，从而有可能达到帕累托最优。
4．假定社会上只有两个人。
对某甲，蚊虫控制的需求曲线为100a q p =-对某乙为200b q p =-（1）假定蚊虫控制是纯公共品：即一旦生产出来，每个人都会从中受益。
如果它能以每单位120美元的不变边际成本得以生产，其最优水平如何？（2）如果蚊虫控制由私人市场来办，又会提供多少？你的答案是否取决于每个人都假定其他人会进行蚊虫控制？（3）如果政府会提供最适当的蚊虫控制规模，这将花费多少？如果个人会按其从蚊虫控制中所得的好处的比例去分担费用的话，为此的税收将怎样在两个人之间分配？ 解：（1）假定蚊虫控制是纯公共品，如果个人对公共物品需求的垂直相加与生产它的边际成本相等，确定的公共物品的数量就是最优水平。
通过垂直相加可得市场需求曲线，对应的市场需求曲线方程为：3002, 0<100200, 100<200q q p q q -≤⎧=⎨-≤⎩ 由p MC =得：90q *=，120p *=即最优水平为90。
（2）给定乙对蚊虫控制的提供量为b q ，因为甲为蚊虫控制愿意支付的最高价格（100）低于进行蚊虫控制的边际成本（120），所以甲的最优选择就是不提供蚊虫控制，即0a q =。
给定甲不会选择提供，乙选择使自己福利最大化的蚊虫控制的供应量：()0max 200d 120b bq b q t t q --⎰ 解得80b q =，因此蚊虫控制的总供应量为80a b q q +=，低于有效供应水平。
（3）如果由政府提供最优的蚊虫控制规模，这将花费120×90＝10800。
把90q *=代入甲乙两人的需求曲线，可得：10a p =，110b p =。
如果个人会按其从蚊虫控制中所得的好处的比例去分担费用的话，甲支付的税收为9010900a a T q p *=⨯=⨯=，乙支付的税收为901109900b b T q p *=⨯=⨯=。
两消费者在总税收中负担比例为：9001990011a b T T ==。
5．假定经济生活中有三种商品，N 个人。
两种商品是纯公共物品（非排他的），第三种商品是普通的私人商品。
（1）为了资源在任意一种公共品与私人商品之间有效率的配置，什么条件成立？（2）为了在两种公共品之间有效配置资源，什么条件一定要成立？ 答：这个问题可以采用如下模型进行解释：假设两种公共品的供应数量为1G 和2G ，每个人消费的私人品的数量为i x ，那么有效的资源配置应当使得全社会的福利最大化，即：()()11212112 max ,,,,0 ..n ni i x x G G i u x G G X G G s tT =∑=，，，， 其中1ni i X x ==∑，()12,,0G T X G =是转换函数，这个问题的拉格朗日函数为：()()121112,,,,i n n i i i i x G G L u G G T x λ==-=∑∑ 相应的一阶条件为：1,2,,i i u T i n x X λ∂∂==∂∂ ①111i n i u T G G λ=∂∂=∑∂∂ ②122i ni u T G G λ=∂∂=∑∂∂ ③（1）由()1,2,,i i u T i n x Xλ∂∂==∂∂，解得,1,2,,i i u x i n T X λ∂∂==∂∂。
②式可进一步改写为1111i n i u T G G λλ=∂∂=∑∂∂，然后把i i u x T X λ∂∂=∂∂，1,2,,i n =代入后整理就有：111i ni i i u G T G T X u x =∂∂∂∂=∑∂∂∂∂对于公共品2，也有类似的等式成立：221i ni i i u G T G T X u x =∂∂∂∂=∑∂∂∂∂（2）②式和③式两边分别相除就得到：111122i ni i n i u T G G T u G G ==∂∂∑∂∂=∂∂∑∂∂6．假定一个生产一种公共品（P ）和一种私人商品（G ）的经济的生产可能性边界由下式决定：221005000G P +=并且，该经济由100个完全相同的个人组成，每个人有如下形式的效用函数i i u G P =其中，i G 是个人在私人商品生产中的份额（/100G ＝）。
请注意，公共品是非排他的，并且每个人都从其生产水平中同样受益。
（1）如果G 和P 的市场是完全竞争的，将会生产出多少？在此情形下典型的个人效用会是什么样的？（2）G 和P 的最优生产水平如何？典型的个人效用水平如何？应怎样对商品的消费进行征税以达到这一结果？解：（1）市场达到竞争性均衡时，每个消费者的边际替代率相同，都等于产品的边际转换率，即iPG PG MRS MRT =，1i =，2，……，100，从而得到：100i G P P G= ① 因为每个人的效用函数都相同，所以利用对称性可知，达到竞争性均衡时，每个人消费的私人品的数量相同，即12100100G G G G ====，从而①式变为： 100100G P P G= ② 联立②式和生产可能性边界方程221005000G P +=，解得0.704P =，70.4G =，从而0.704i G =，此时每个的效用为0.704i u =。
（2）根据公共品供给的萨缪尔森加总规则，公共品和私人品达到最优分配时应当满足如下条件：1001i PG PG i MRS MRT ==∑即：1001100i i G P p G ==∑③ 因为每个人的效用函数都相同，所以利用对称性可知，达到最优时，每个人消费的私人品的数量相同，即12100100G G G G ====，从而③式变为： 100G P P G= ④ ④式和生产可能性边界方程221005000G P +=，联立解得5P =，50G =，从而0.5i G =，1i =，2，…，1000.510i G P =。
政府可以通过向消费者消费公共品征收数量税，使得在竞争条件下商品的供给达到有效数量。
假设私人品的价格为1（这相当于把私人品作为计价物），公共品的税率为t ，那么达到竞争性均衡时，每个消费者的边际替代率相同，都等于私人品和公共品的价格之比（公共品的价格即税率），即iPG MRS t =，从而得到：i G t P= ⑤ 把5P =和0.5i G =代入⑤式中，解得0.1t =。
7．若市场上只有A 和B 两个消费者，他们对公共品Y 的需求函数，以及Y 的供给函数分别为8212dA YdB Y sY YQ p Q p Q p =-=-=求：（1）A 、B 各消费多少Y ？（2）Y 的市场价格是多少？（3）若Y 是个人品，其价格和消费量有何不同？解：（1）由于公共品具有非排他性，即一个人提供时，所有的人都可以使用，所以给定消费者B 提供的数量为B Q ，消费者A 选择使自己的消费者剩余最大化的提供量，即：()0max 40.5d AB A Q Q A Q t t PQ +--⎰ ①把A B P Q Q =+代入①式中，就有：22531max 44424A A B A B B Q Q Q Q Q Q ⎡⎤⎛⎫⎛⎫-+-+- ⎪ ⎪⎢⎥⎝⎭⎝⎭⎣⎦ 解得：853508083B B A B Q Q Q Q -≤<⎧=⎨≥⎩ ②同理，对于消费者B 也有：4230606A A B A Q Q Q Q -≤<⎧=⎨≥⎩ ③联立②、③两式，解得0A Q =，4B Q =。