《上海财经大学中级微观经济学课程叶正茂课件》由会员分享，可在线阅读，更多相关《上海财经大学中级微观经济学课程叶正茂课件（200页珍藏版）》请在金锄头文库上搜索。
1、第七章第七章 市场失灵市场失灵u市场失灵的四种情形市场失灵的四种情形:u垄断垄断u外部性（外部效应）外部性（外部效应）u公共物品公共物品u不对称信息不对称信息上海财经大学中级微观经济学课程(叶正茂)7.1 外部性外部性ExternalitiesuAn externality is a cost or a benefit imposed upon someone by actions taken by others. The cost or benefit is thus generated externally to that somebody.uAn externally imposed b
2、enefit is a positive externality（正外部性）.uAn externally imposed cost is a negative externality（负外部性）.上海财经大学中级微观经济学课程(叶正茂)Examples of Negative ExternalitiesuAir pollution.uWater pollution.uLoud parties next door.uTraffic congestion.uSecond-hand cigarette smoke.uIncreased insurance premiums due to alcoh
3、ol or tobacco consumption.上海财经大学中级微观经济学课程(叶正茂)Examples of Positive ExternalitiesuA well-maintained property next door that raises the market value of your property.uA pleasant cologne （科隆香水）or scent worn by the person seated next to you.uImproved driving habits that reduce accident risks.uA scientif
4、ic advance.上海财经大学中级微观经济学课程(叶正茂)Externalities and EfficiencyuExternalities cause Pareto inefficiency; typicallytoo much scarce resource is allocated to an activity which causes a negative externalitytoo little resource is allocated to an activity which causes a positive externality.上海财经大学中级微观经济学课程(叶正
5、茂)Inefficiency & Negative ExternalitiesuConsider two agents, A and B, and two commodities, money and smoke.uBoth smoke and money are goods for Agent A.uMoney is a good and smoke is a bad for Agent B.uSmoke is a purely public commodity.上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesuAgent A
6、 is endowed with $yA.uAgent B is endowed with $yB.uSmoke intensity is measured on a scale from 0 (no smoke) to 1 (maximum concentration).上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOA10SmokemAyAMoney and smoke areboth goods for Agent A.上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative Externa
7、litiesOA10SmokemAyAMoney and smoke areboth goods for Agent A.Better上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOB10SmokemByBMoney is a good and smokeis a bad for Agent B.Better上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOB10SmokemByBMoney is a good and smokeis a bad for Age
8、nt B.Better上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesuWhat are the efficient allocations of smoke and money?上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经
9、济学课程(叶正茂)Inefficiency & Negative ExternalitiesOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesuSuppose there is no means by which money can be exchanged for chang
10、es in smoke level.uWhat then is Agent As most preferred allocation?uIs this allocation efficient?上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocati
11、onsAs choices上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations As mostpreferred choiceis inefficient上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesuContinue to suppose there is no means by which money can be exchanged for changes in smo
12、ke level.uWhat is Agent Bs most preferred allocation?uIs this allocation efficient?上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocationsBs choices上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations
13、Bs mostpreferred choice上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesOA10SmokemAOB10SmokemByAyBEfficientallocations Bs mostpreferred choiceis inefficient上海财经大学中级微观经济学课程(叶正茂)Inefficiency & Negative ExternalitiesuSo if A and B cannot trade money for changes in smoke intensity, then the outc
14、ome is inefficient.uEither there is too much smoke (As most preferred choice) or there is too little smoke (Bs choice).上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsuRonald Coases insight is that most externality problems are due to an inadequate specification of property rights and, conseque
15、ntly, an absence of markets in which trade can be used to internalize external costs or benefits.上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsuNeither Agent A nor Agent B owns the air in their room.uWhat happens if this property right is created and is assigned to one of them?上海财经大学中级微观经济学课程
16、(叶正茂)Externalities and Property RightsuSuppose Agent B is assigned ownership of the air in the room.uAgent B can now sell “rights to smoke”.uWill there be any smoking?uIf so, how much smoking and what will be the price for this amount of smoke?上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsuLe
17、t p(sA) be the price paid by Agent A to Agent B in order to create a smoke intensity of sA.上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property Righ
18、tsOA10SmokemAOB10SmokemByAyBp(sA)sA上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyBp(sA)Both agentsgain andthere is apositiveamount ofsmoking.sA上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyBp(sA)sAEstablishinga market fortrading rightst
19、o smoke causes an efficientallocation tobe achieved.上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsuSuppose instead that Agent A is assigned the ownership of the air in the room.uAgent B can now pay Agent A to reduce the smoke intensity.uHow much smoking will there be?uHow much money will Agen
20、t B pay to Agent A?上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyBsBp(sB)上海财经大学中级微观经济学课程(叶正茂)Externalities and
21、 Property RightsOA10SmokemAOB10SmokemByAyBp(sB)Both agentsgain andthere is areducedamount ofsmoking.sB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyBp(sB)Establishinga market fortrading rightsto reducesmoke causes an efficientallocation tobe achieved.sB上海财经大学中级微观经济学课程
22、(叶正茂)Externalities and Property RightsuNotice that theagent given the property right (asset) is better off than at her own most preferred allocation in the absence of the property right.amount of smoking that occurs in equilibrium depends upon which agent is assigned the property right.上海财经大学中级微观经济学
23、课程(叶正茂)Externalities and Property RightsOA10SmokemAOB10SmokemByAyBp(sB)p(sA)sA sBsBsA上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsuIs there a case in which the same amount of smoking occurs in equilibrium no matter which agent is assigned ownership of the air in the room?上海财经大学中级微观经济学课程(叶正茂)
24、Externalities and Property RightsOA10SmokemAOB10SmokemByAyBp(sB)p(sA)sA = sB上海财经大学中级微观经济学课程(叶正茂)Externalities and Property RightsOA10SmokeOB10SmokeyAyBp(sB)p(sA)sA = sBFor both agents, the MRS is constant asmoney changes, for given smoke intensity.上海财经大学中级微观经济学课程(叶正茂)Externalities and Property Right
25、sOA10SmokeOB10SmokeyAyBp(sB)p(sA)sA = sBSo, for both agents, preferences must bequasilinear in money; U(m,s) = m + f(s).上海财经大学中级微观经济学课程(叶正茂)Coases TheoremuCoases Theorem is: If all agents preferences are quasilinear in money, then the same efficient level of the externality generating commodity is p
26、roduced no matter which agent is assigned the property right.上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesuA steel mill produces jointly steel and pollution.uThe pollution adversely affects a nearby fishery.uBoth firms are price-takers.upS is the market price of steel.upF is the market price of fish.
27、上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesucS(s,x) is the steel firms cost of producing s units of steel jointly with x units of pollution.uIf the steel firm does not face any of the external costs of its pollution production then its profit function is and the firms problem is to上海财经大学中级微观经济学课程(叶
28、正茂)Production ExternalitiesThe first-order profit-maximizationconditions are上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesThe first-order profit-maximizationconditions areand上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesstates that the steel firmshould produce the output level of steelfor which price =
29、marginal production cost.上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesstates that the steel firmshould produce the output level of steelfor which price = marginal production cost.is the rate at which the firmsinternal production cost goes down as thepollution level rises上海财经大学中级微观经济学课程(叶正茂)Production
30、 Externalitiesstates that the steel firmshould produce the output level of steelfor which price = marginal production cost.is the rate at which the firmsinternal production cost goes down as thepollution level rises, sois the marginal cost to the firm of pollution reduction（减少）减少）.上海财经大学中级微观经济学课程(叶正
31、茂)Production Externalitiesis the marginal cost to thefirm of pollution reduction.What is the marginal benefit to the steelfirm from reducing pollution?上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesis the marginal cost to thefirm of pollution reduction.What is the marginal benefit to the steelfirm from
32、 reducing pollution?Zero, since the firm does not face itsexternal cost.Hence the steel firm chooses the pollutionlevel for which上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesand the first-order profit-maximizationconditions areandE.g. suppose cS(s,x) = s2 + (x - 4)2 andpS = 12. Then上海财经大学中级微观经济学课程(叶正
33、茂)Production Externalitiesdetermines the profit-max.output level of steel; s* = 6.上海财经大学中级微观经济学课程(叶正茂)Production Externalitiesdetermines the profit-max.output level of steel; s* = 6.is the marginal cost to the firmfrom pollution reduction. Since it getsno benefit from this it sets x* = 4. 上海财经大学中级微观
34、经济学课程(叶正茂)Production Externalitiesdetermines the profit-max.output level of steel; s* = 6.is the marginal cost to the firmfrom pollution reduction. Since it getsno benefit from this it sets x* = 4. The steel firms maximum profit level isthus上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesuThe cost to th
35、e fishery of catching f units of fish when the steel mill emits x units of pollution is cF(f,x). Given f, cF(f,x) increases with x; i.e. the steel firm inflicts a negative externality on the fishery.上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesuThe cost to the fishery of catching f units of fish when
36、 the steel mill emits x units of pollution is cF(f,x). Given f, cF(f,x) increases with x; i.e. the steel firm inflicts a negative externality on the fishery.uThe fisherys profit function isso the fisherys problem is to上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesThe first-order profit-maximizationcon
37、dition is上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesThe first-order profit-maximizationcondition is上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesThe first-order profit-maximizationcondition isHigher pollution raises the fisherysmarginal production cost and lowers bothits output level and its profit.
38、This is theexternal cost of the pollution.上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesE.g. suppose cF(f;x) = f2 + xf and pF = 10.The external cost inflicted on the fisheryby the steel firm is xf. Since the fisheryhas no control over x it must take the steelfirms choice of x as a given. The fisherysp
39、rofit function is thus上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesGiven x, the first-order profit-maximizationcondition is上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesGiven x, the first-order profit-maximizationcondition isSo, given a pollution level x inflicted uponit, the fisherys profit-maximizing
40、 outputlevel is上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesGiven x, the first-order profit-maximizationcondition isSo, given a pollution level x inflicted uponit, the fisherys profit-maximizing outputlevel isNotice that the fishery produces less, andearns less profit, as the steel firmspollution lev
41、el increases.上海财经大学中级微观经济学课程(叶正茂)Production Externalities The steel firm, ignoring its external cost inflicted upon the fishery,chooses x* = 4, so the fisherysprofit-maximizing output level given thesteel firms choice of pollution level isf* = 3, giving the fishery a maximumprofit level ofNotice tha
42、t the external cost is $12.上海财经大学中级微观经济学课程(叶正茂)Production ExternalitiesuAre these choices by the two firms efficient?uWhen the steel firm ignores the external costs of its choices, the sum of the two firms profits is $36 + $9 = $45.uIs $45 the largest possible total profit that can be achieved?上海财经大
43、学中级微观经济学课程(叶正茂)Merger and InternalizationuSuppose the two firms merge to become one. What is the highest profit this new firm can achieve?上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationuSuppose the two firms merge to become one. What is the highest profit this new firm can achieve?uWhat choices of s,
44、 f and x maximize the new firms profit?上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationThe first-order profit-maximizationconditions areThe solution is上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationAnd the merged firms maximum profitlevel isThis exceeds $45, the sum of the non-merged firms.上海财经大学中级微观经济
45、学课程(叶正茂)Merger and InternalizationuMerger has improved efficiency.uOn its own, the steel firm produced x* = 4 units of pollution.uWithin the merged firm, pollution production is only xm = 2 units.uSo merger has caused both an improvement in efficiency and less pollution production. Why?上海财经大学中级微观经济学
46、课程(叶正茂)Merger and InternalizationThe steel firms profit function is so the marginal cost of producing x unitsof pollution isWhen it does not have to face theexternal costs of its pollution, the steelfirm increases pollution until this marginalcost is zero; hence x* = 4.上海财经大学中级微观经济学课程(叶正茂)Merger and
47、 InternalizationIn the merged firm the profit function isThe marginal cost of pollution is thus上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationIn the merged firm the profit function isThe marginal cost of pollution is上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationIn the merged firm the profit function
48、isThe marginal cost of pollution isThe merged firms marginal pollution costis larger because it faces the full cost ofits own pollution through increased costsof production in the fishery, so lesspollution is produced by the merged firm.上海财经大学中级微观经济学课程(叶正茂)Merger and InternalizationuMerger therefore
49、 internalizes an externality and induces economic efficiency.uHow else might internalization be caused so that efficiency can be achieved?u方法二是收税，见书上方法二是收税，见书上500页。页。u方法三是界定产权。方法三是界定产权。上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesuCoase argues that the externality exists because neither the
50、 steel firm nor the fishery owns the water being polluted.uSuppose the property right to the water is created and assigned to one of the firms. Does this induce efficiency?上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesuSuppose the fishery owns the water.uThen it can sell pollution rights, in
51、 a competitive market, at $px each.uThe fisherys profit function becomes上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesuSuppose the fishery owns the water.uThen it can sell pollution rights, in a competitive market, at $px each.uThe fisherys profit function becomesuGiven pf and px, how many f
52、ish and how many rights does the fishery wish to produce? (Notice that x is now a choice variable for the fishery.)上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesThe profit-maximum conditions are上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesThe profit-maximum conditions areand these g
53、ive(fish supply)(pollutionright supply)上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesuThe steel firm must buy one right for every unit of pollution it emits so its profit function becomesuGiven pf and px, how much steel does the steel firm want to produce and how many rights does it wish to
54、buy?上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesThe profit-maximum conditions are上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesThe profit-maximum conditions areand these give(steel supply)(pollutionright demand)上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesIn a competitive
55、market for pollution rightsthe price px must adjust to clear the marketso, at equilibrium,上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesIn a competitive market for pollution rightsthe price px must adjust to clear the marketso, at equilibrium,The market-clearing price for pollutionrights is
56、thus上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesIn a competitive market for pollution rightsthe price px must adjust to clear the marketso, at equilibrium,The market-clearing price for pollutionrights is thusand the equilibrium quantity of rightstraded is上海财经大学中级微观经济学课程(叶正茂)Coase and Produ
57、ction Externalities上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesSo if ps = 12 and pf = 10 thenThis is the efficient outcome.上海财经大学中级微观经济学课程(叶正茂)Coase and Production ExternalitiesuQ: Would it matter if the property right to the water had instead been assigned to the steel firm?uA: Coases The
58、orem states that the same efficient allocation is achieved whichever of the firms was assigned the property right. (And the asset owner gets richer.)上海财经大学中级微观经济学课程(叶正茂)u如果产权明确界定，外部性就不会带来如果产权明确界定，外部性就不会带来什么问题。什么问题。u但如果产权界定不明确的话，就会带来但如果产权界定不明确的话，就会带来无效率。无效率。u最著名的例子就是最著名的例子就是“公地的悲剧公地的悲剧”。上海财经大学中级微观经济学
59、课程(叶正茂)The Tragedy of the CommonsuConsider a grazing area owned “in common” by all members of a village.uVillagers graze cows on the common.uWhen c cows are grazed, total milk production is f(c), where f0 and f” 0 and f” 0 and f” $100, so supplying the good is Pareto-improving.上海财经大学中级微观经济学课程(叶正茂)Fr
60、ee-RidingBuyDontBuyBuyDontBuyPlayer APlayer B上海财经大学中级微观经济学课程(叶正茂)Free-RidingBuyDontBuyBuyDontBuyPlayer APlayer B(Dont Buy, Dont Buy) is the unique NE.上海财经大学中级微观经济学课程(叶正茂)Free-RidingBuyDontBuyBuyDontBuyPlayer APlayer BBut (Dont Buy, Dont Buy) is inefficient.上海财经大学中级微观经济学课程(叶正茂)怎样确定公共产品的消费水平Variable P
61、ublic Good QuantitiesuE.g. how many broadcast TV programs, or how much land to include into a national park.u不同水平的公共产品uc(G) is the production cost of G units of public good.uTwo individuals, A and B.uPrivate consumptions are xA, xB.上海财经大学中级微观经济学课程(叶正茂)Variable Public Good QuantitiesuBudget allocatio
62、ns must satisfy上海财经大学中级微观经济学课程(叶正茂)Variable Public Good QuantitiesuBudget allocations must satisfyuMRSA & MRSB are A & Bs marg. rates of substitution between the private and public goods.uPareto efficiency condition for public good supply is 见见530-531页的说明以及图页的说明以及图35.1。上海财经大学中级微观经济学课程(叶正茂)Variable P
63、ublic Good QuantitiesuHence, necessarily, efficient public good production requiresuSuppose there are n consumers; i = 1,n. Then efficient public good production requires 数学证明见数学证明见543页附录页附录上海财经大学中级微观经济学课程(叶正茂)Efficient Public Good Supply - the Quasilinear Preferences CaseuTwo consumers, A and B.u 上
64、海财经大学中级微观经济学课程(叶正茂)Efficient Public Good Supply - the Quasilinear Preferences Caseu拟线性偏好的效用表达式：拟线性偏好的效用表达式：u Ui(xi,G)=xi+vi(G) 一切公共物品的帕累托有效率一切公共物品的帕累托有效率水平必须满足：水平必须满足：这就是说，私人物品的边际效用总是等于这就是说，私人物品的边际效用总是等于1u所以所以MRSi= vi(G)/ G 见书上见书上532页页上海财经大学中级微观经济学课程(叶正茂)Efficient Public Good Supply - the Quasilinea
65、r Preferences Caseu v1(G)/ G+ v2(G)/ G=MC(G)u该方程式决定了该方程式决定了G,而与而与x1和和x2根本无根本无关，因此存在一个唯一的公共物品有关，因此存在一个唯一的公共物品有效供给数量。效供给数量。u同时表明：同时表明：Efficient public good supply requires A & B to state truthfully their marginal valuations.上海财经大学中级微观经济学课程(叶正茂)Free-Riding RevisiteduWhen is free-riding individually rat
66、ional?uIndividuals can contribute only positively to public good supply; nobody can lower the supply level.uIndividual utility-maximization may require a lower public good level.uFree-riding is rational in such cases.u一个人认为另一个人所购买的公共物品正好购一个人认为另一个人所购买的公共物品正好购用，我们可以用下面的图形说明。用，我们可以用下面的图形说明。上海财经大学中级微观经济
67、学课程(叶正茂)Free-Riding RevisiteduGiven A contributes gA units of public good, Bs problem issubject to上海财经大学中级微观经济学课程(叶正茂)Free-Riding RevisitedGxBgABs budget constraint; slope = -1上海财经大学中级微观经济学课程(叶正茂)Free-Riding RevisitedGxBgABs budget constraint; slope = -1is not allowed上海财经大学中级微观经济学课程(叶正茂)Free-Riding
68、RevisitedGxBgABs budget constraint; slope = -1is not allowed上海财经大学中级微观经济学课程(叶正茂)Free-Riding RevisitedGxBgABs budget constraint; slope = -1is not allowed上海财经大学中级微观经济学课程(叶正茂)Free-Riding RevisitedGxBgABs budget constraint; slope = -1is not allowed(i.e. free-riding) is best for B上海财经大学中级微观经济学课程(叶正茂)Dema
69、nd Revelation与克拉克税与克拉克税uA scheme that makes it rational for individuals to reveal truthfully their private valuations of a public good is a revelation mechanism.uE.g. the Groves-Clarke taxation scheme.uHow does it work?上海财经大学中级微观经济学课程(叶正茂)Demand RevelationuN individuals; i = 1,N.uAll have quasi-line
70、ar preferences.uvi is individual is true (private) valuation of the public good.uIndividual i must provide ci private good units if the public good is supplied.u ci表示购买公共物品每个人所负担的成本上海财经大学中级微观经济学课程(叶正茂)Demand Revelationuni = vi - ci is net value, for i = 1,N.uPareto-improving to supply the public goo
71、d if上海财经大学中级微观经济学课程(叶正茂)Demand Revelationuni = vi - ci is net value, for i = 1,N.uPareto-improving to supply the public good if上海财经大学中级微观经济学课程(叶正茂)Demand RevelationuIf andor andthen individual j is pivotal（关键人物）（关键人物）; i.e. changes the supply decision. 上海财经大学中级微观经济学课程(叶正茂)Demand RevelationuWhat loss
72、 does a pivotal individual j inflict on others?上海财经大学中级微观经济学课程(叶正茂)Demand RevelationuWhat loss does a pivotal individual j inflict on others?uIf then is the loss.上海财经大学中级微观经济学课程(叶正茂)Demand RevelationuWhat loss does a pivotal individual j inflict on others?（对别人造成的损失）uIf then is the loss.uIf then is t
73、he loss.上海财经大学中级微观经济学课程(叶正茂)Demand RevelationuFor efficiency, a pivotal agent must face the full cost or benefit of her action.uThe GC tax scheme makes pivotal agents face the full stated costs or benefits of their actions in a way that makes these statements truthful.上海财经大学中级微观经济学课程(叶正茂)Demand Reve
74、lationuThe GC tax scheme:见书上见书上540页。页。uAssign a cost ci to each individual.uEach agent states a public good net valuation, si.uPublic good is supplied if uotherwise not.上海财经大学中级微观经济学课程(叶正茂)Demand RevelationuA pivotal person j who changes the outcome from supply to not supplypays a tax of上海财经大学中级微观经济
75、学课程(叶正茂)Demand RevelationuA pivotal person j who changes the outcome from supply to not supplypays a tax ofuA pivotal person j who changes the outcome from not supply to supplypays a tax of上海财经大学中级微观经济学课程(叶正茂)Demand RevelationuNote: Taxes are not paid to other individuals, but to some other agent ou
76、tside the market.例如缴纳给国家。上海财经大学中级微观经济学课程(叶正茂)Demand RevelationuWhy is the GC tax scheme a revelation mechanism?u见书上见书上540-541页的例子。页的例子。上海财经大学中级微观经济学课程(叶正茂)Demand RevelationuGC tax scheme implements efficient supply of the public good.uBut, causes an inefficiency due to taxes removing private good fr
77、om pivotal individuals.u因为必须缴纳税收，私人消费最终将低因为必须缴纳税收，私人消费最终将低于可能达到的水平，因而这是一种帕累于可能达到的水平，因而这是一种帕累托低效率。托低效率。上海财经大学中级微观经济学课程(叶正茂)7.3 不对称信息不对称信息Asymmetric Information上海财经大学中级微观经济学课程(叶正茂)Information in Competitive MarketsuIn purely competitive markets all agents are fully informed about traded commodities an
78、d other aspects of the market.（信息是完全的，对称的）uWhat about markets for medical services, or insurance, or used cars?上海财经大学中级微观经济学课程(叶正茂)Asymmetric Information in MarketsuA doctor knows more about medical services than does the buyer.uAn insurance buyer knows more about his riskiness than does the seller.
79、 uA used cars owner knows more about it than does a potential buyer.上海财经大学中级微观经济学课程(叶正茂)Asymmetric Information in MarketsuMarkets with one side or the other imperfectly informed are markets with imperfect information.uImperfectly informed markets with one side better informed than the other are mark
80、ets with asymmetric information.上海财经大学中级微观经济学课程(叶正茂)Asymmetric Information in MarketsuIn what ways can asymmetric information affect the functioning of a market?uFour applications will be considered:0adverse selection 0signaling （对策）0moral hazard0incentives contracting（对策）.上海财经大学中级微观经济学课程(叶正茂)Advers
81、e SelectionuConsider a used car market.uTwo types of cars; “lemons” and “peaches”.uEach lemon seller will accept $1,000; a buyer will pay at most $1,200.uEach peach seller will accept $2,000; a buyer will pay at most $2,400.上海财经大学中级微观经济学课程(叶正茂)Adverse SelectionuIf every buyer can tell a peach from a
82、 lemon, then lemons sell for between $1,000 and $1,200, and peaches sell for between $2,000 and $2,400.uGains-to-trade are generated when buyers are well informed.上海财经大学中级微观经济学课程(叶正茂)Adverse SelectionuSuppose no buyer can tell a peach from a lemon before buying.uWhat is the most a buyer will pay for
83、 any car?上海财经大学中级微观经济学课程(叶正茂)Adverse SelectionuLet q be the fraction of peaches.u1 - q is the fraction of lemons.uExpected value to a buyer of any car is at most上海财经大学中级微观经济学课程(叶正茂)Adverse SelectionuSuppose EV $2000，即当q2/3时，uEvery seller can negotiate a price between $2000 and $EV (no matter if the
84、car is a lemon or a peach).uAll sellers gain from being in the market.上海财经大学中级微观经济学课程(叶正茂)Adverse SelectionuBut, Suppose EV $2000.当q2/3时uA peach seller cannot negotiate a price above $2000 and will exit the market. 高质量的Peaches将退出市场。 uSo all buyers know that remaining sellers own lemons only.uBuyers
85、will pay at most $1200 and only lemons are sold.上海财经大学中级微观经济学课程(叶正茂)Adverse SelectionuHence “too many” lemons “crowd out” the peaches from the market.“劣币驱逐良币”uGains-to-trade are reduced since no peaches are traded.uThe presence of the lemons inflicts an external cost on buyers and peach owners.上海财经大
86、学中级微观经济学课程(叶正茂)Adverse SelectionuHow many lemons can be in the market without crowding out the peaches?uBuyers will pay $2000 for a car only if上海财经大学中级微观经济学课程(叶正茂)Adverse SelectionuHow many lemons can be in the market without crowding out the peaches?uBuyers will pay $2000 for a car only ifuSo if ov
87、er one-third of all cars are lemons, then only lemons are traded.上海财经大学中级微观经济学课程(叶正茂)Adverse SelectionuAdverse selection has destroyed the entire market!上海财经大学中级微观经济学课程(叶正茂)SignalinguAdverse selection is an outcome of an informational deficiency.uWhat if information can be improved by high-quality s
88、ellers signaling credibly that they are high-quality?uE.g. warranties, professional credentials, references from previous clients etc.上海财经大学中级微观经济学课程(叶正茂)Moral HazarduIf you have full car insurance are you more likely to leave your car unlocked?uMoral hazard is a reaction to incentives to increase t
89、he risk of a lossu道德风险指的是市场的一方不能察知另一方的行动uand is a consequence of asymmetric information.u而逆向选择指的是市场的一方不能察知另一方的商品质量或类型。上海财经大学中级微观经济学课程(叶正茂)Moral HazarduIf an insurer（保险公司） knows the exact risk from insuring an individual, then a contract specific to that person can be written.uIf all people look alik
90、e to the insurer, then one contract will be offered to all insurees; high-risk and low-risk types are then pooled, causing low-risks to subsidize high-risks.上海财经大学中级微观经济学课程(叶正茂)Moral HazarduExamples of efforts to avoid moral hazard by using signals are:0 higher life and medical insurance premiums fo
91、r smokers or heavy drinkers of alcohol0 lower car insurance premiums for contracts with drivers with histories of safe driving.上海财经大学中级微观经济学课程(叶正茂)Incentives ContractinguA worker is hired by a principal to do a task.uOnly the worker knows the effort she exerts (asymmetric information). But the princ
92、iple does not know.uThe effort exerted affects the principals payoff.上海财经大学中级微观经济学课程(叶正茂)Incentives ContractinguThe principals problem: design an incentives contract that induces the worker to exert the amount of effort that maximizes the principals payoff.上海财经大学中级微观经济学课程(叶正茂)Incentives Contractingu
93、e is the workers effort（劳动量）.uPrincipals reward isuAn incentive contract is a function s(y) specifying the workers payment when the principals reward is y. The principals profit is thus上海财经大学中级微观经济学课程(叶正茂)Incentives ContractinguLet be the workers (reservation) utility of not working.uTo get the work
94、ers participation, the contract must offer the worker a utility of at leastuThe workers utility cost of an effort level e is c(e).上海财经大学中级微观经济学课程(叶正茂)Incentives ContractingSo the principals problem is choose e tosubject to(participation constraint)To maximize his profit the principaldesigns the cont
95、ract to provide the worker with her reservation utility level. That is, .上海财经大学中级微观经济学课程(叶正茂)Incentives Contractingthe principals problem is tosubject to(participation constraint)上海财经大学中级微观经济学课程(叶正茂)Incentives Contractingthe principals problem is tosubject to(participation constraint)Substitute for
96、and solve上海财经大学中级微观经济学课程(叶正茂)Incentives Contractingthe principals problem is tosubject to(participation constraint)The principals profit is maximized when边际劳动产品边际劳动产品=边际劳动成本边际劳动成本Substitute for and solve上海财经大学中级微观经济学课程(叶正茂)Incentives ContractingThe contract that maximizes theprincipals profit insist
97、s upon theworker effort level e* that equalizesthe workers marginal effort cost tothe principals marginal payoff fromworker effort.上海财经大学中级微观经济学课程(叶正茂)Incentives ContractingHow can the principal induce theworker to choose e = e*?The contract that maximizes theprincipals profit insists upon theworker
98、 effort level e* that equalizesthe workers marginal effort cost tothe principals marginal payoff fromworker effort.上海财经大学中级微观经济学课程(叶正茂)Incentives Contractingue = e* must be most preferred by the worker.上海财经大学中级微观经济学课程(叶正茂)Incentives Contractingue = e* must be most preferred by the worker.uSo the con
99、tract s(y) must satisfy the incentive-compatibility constraint（激励相容约束）u它表示，工人选取e* 的效用一定大于他选择其他劳动量而获得的效用。上海财经大学中级微观经济学课程(叶正茂)u因此激励计划必须满足的两个约束条件：因此激励计划必须满足的两个约束条件：u（1）激励计划必须使工人得到总效用）激励计划必须使工人得到总效用u（2）激励计划必须使劳动水平）激励计划必须使劳动水平e* 处的边际劳动处的边际劳动产品产品=边际劳动成本。边际劳动成本。u可以选择的方法：可以选择的方法：上海财经大学中级微观经济学课程(叶正茂)Incentiv
100、es contractsuExamples of incentives contracts:(1) Rental contracts: The principal keeps a lump-sum R for himself and the worker gets all profit above R; i.e. uWhy does this contract maximize the principals profit?上海财经大学中级微观经济学课程(叶正茂)uGiven the contractthe workers payoff isand to maximize this the wo
101、rker should choose the effort level for which上海财经大学中级微观经济学课程(叶正茂)uHow large should be the principals rental fee R?uThe principal should extract as much rent as possible without causing the worker not to participate, so R should satisfyi.e.上海财经大学中级微观经济学课程(叶正茂)u(2) Wages contracts: In a wages contract
102、 the payment to the worker isw is the wage per unit of effort.K is a lump-sum payment.u max we+K-c(e)得到w=c(e)u而工资上海财经大学中级微观经济学课程(叶正茂)u(3) Take-it-or-leave-it: Choose e = e* and be paid a lump-sum B, B -c( e* )=u0 (u0为工人的其他选择所获得的效用）为工人的其他选择所获得的效用） or choose e e* and be paid zero.uThe workers utility
103、from choosing e e* is - c(e), so the worker will choose e = e*.上海财经大学中级微观经济学课程(叶正茂)Incentives Contracts in GeneraluThe common feature of all efficient incentive contracts is that they make the worker the full residual claimant on profits.uI.e. the last part of profit earned must accrue entirely to the worker.上海财经大学中级微观经济学课程(叶正茂)Other contractsu(4)分成制：见书上分成制：见书上556页。页。u显然，它是一种非最优激励计划。显然，它是一种非最优激励计划。上海财经大学中级微观经济学课程(叶正茂)
