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SUPPLYANDDEMANDII:MARKETSANDWELFARE供給與需求（II）：市場(chǎng)和福利Consumers,Producers,andtheEfficiencyofMarkets

消費(fèi)者、生產(chǎn)者

與市場(chǎng)效率Chapter7RevisitingtheMarketEquilibriumDotheequilibriumpriceandquantitymaximizethetotalwelfareofbuyersandsellers? Marketequilibriumreflectsthewaymarketsallocatescarceresources.

Whetherthemarketallocationisdesirableisdeterminedbywelfareeconomics.回顧市場(chǎng)均衡市場(chǎng)均衡價(jià)格和數(shù)量能否使買(mǎi)者和賣(mài)者的總利益最大化？市場(chǎng)均衡反映了市場(chǎng)配置稀缺資源的方式。

市場(chǎng)配置資源是否合意可以根據(jù)福利經(jīng)濟(jì)學(xué)理論判定。WelfareEconomics

Welfareeconomics

isthestudyofhowtheallocationof

resourcesaffectseconomicwell-being.Buyersandsellersreceivebenefitsfromtakingpartinthemarket.Theequilibriuminamarketmaximizesthetotalwelfareofbuyersandsellers.福利經(jīng)濟(jì)學(xué)

福利經(jīng)濟(jì)學(xué)——研究資源配置如何影響經(jīng)濟(jì)福利。買(mǎi)者和賣(mài)者可以從參與市場(chǎng)活動(dòng)中獲得利益。市場(chǎng)均衡可以使買(mǎi)者和賣(mài)者的總利益最大化。WelfareEconomics福利經(jīng)濟(jì)學(xué)Equilibriuminthemarketresultsinmaximumbenefits,andthereforemaximumtotalwelfareforboththeconsumersandtheproducersoftheproduct.市場(chǎng)均衡使利益最大化，即使產(chǎn)品的消費(fèi)者和生產(chǎn)者的總利益最大化。WelfareEconomics

福利經(jīng)濟(jì)學(xué)Consumersurplusmeasureseconomicwelfarefromthebuyer’sside.

消費(fèi)者剩余從消費(fèi)者角度衡量經(jīng)濟(jì)福利。Producersurplusmeasureseconomicwelfarefromtheseller’s

side.

生產(chǎn)者剩余從生產(chǎn)者角度衡量經(jīng)濟(jì)福利。ConsumerSurplus消費(fèi)者剩余Willingnesstopayisthemaximumpricethatabuyeriswillingandabletopayforagood.

支付意愿——買(mǎi)者為某種物品愿意和能夠支付的最高價(jià)格。Itmeasureshowmuchthebuyervaluesthegoodorservice.

它衡量買(mǎi)者對(duì)物品的評(píng)價(jià)是多少。ConsumerSurplus消費(fèi)者剩余Consumersurplus

istheamountabuyeriswillingtopayforagoodminustheamountthebuyeractuallypaysforit.消費(fèi)者剩余

——買(mǎi)者支付意愿減去買(mǎi)者的實(shí)際支付量。FourPossibleBuyers’WillingnesstoPay...

四個(gè)可能買(mǎi)者的支付意愿…ConsumerSurplus消費(fèi)者剩余Themarketdemandcurvedepictsthevariousquantitiesthatbuyerswouldbewillingandabletopurchaseatdifferentprices.市場(chǎng)需求曲線(xiàn)表示在不同價(jià)格水平下，買(mǎi)者愿意和能夠購(gòu)買(mǎi)的數(shù)量。TheDemandScheduleandtheDemandCurve需求表與需求曲線(xiàn)Figure1TheDemandScheduleandtheDemandCurvePriceofAlbum5070800$1001234QuantityofAlbumsJohn’swillingnesstopayPaul’swillingnesstopayGeorge’swillingnesstopayRingo’swillingnesstopayDemand圖1.需求表與需求曲線(xiàn)專(zhuān)輯的價(jià)格5070800$1001234專(zhuān)輯的數(shù)量約翰的支付意愿保羅的支付意愿喬治的支付意愿林格的支付意愿需求MeasuringConsumerSurpluswiththeDemandCurve...PriceofAlbum5070800$1001234QuantityofAlbumsDemandJohn’sconsumersurplus($20)Price=$80用需求曲線(xiàn)衡量消費(fèi)者剩余...專(zhuān)輯的價(jià)格5070800$1001234專(zhuān)輯的數(shù)量需求約翰的消費(fèi)者剩余（20美元）價(jià)格=80美元Figure2MeasuringConsumerSurpluswiththeDemandCurve(b)Price=$70PriceofAlbum5070800$100Demand1234Totalconsumersurplus($40)QuantityofAlbumsJohn’sconsumersurplus($30)Paul’sconsumersurplus($10)圖2.用需求曲線(xiàn)衡量消費(fèi)者剩余(b)價(jià)格=70美元專(zhuān)輯的價(jià)格5070800$100需求1234總消費(fèi)者剩余(40美元)專(zhuān)輯的數(shù)量約翰的消費(fèi)者剩余(30美元)’保羅的消費(fèi)者剩余(10美元)’MeasuringConsumerSurpluswiththeDemandCurve

用需求曲線(xiàn)衡量消費(fèi)者剩余Theareabelowthedemandcurveandabovethepricemeasurestheconsumersurplusinthemarket.需求曲線(xiàn)以下和價(jià)格以上的面積衡量市場(chǎng)的消費(fèi)者剩余。Figure3HowthePriceAffects

ConsumerSurplusConsumersurplusQuantity(a)ConsumerSurplusatPricePPrice0DemandP1Q1BAC圖3.價(jià)格如何影響消費(fèi)者剩余消費(fèi)者剩余數(shù)量(a)價(jià)格在P價(jià)格0需求P1Q1BAC時(shí)的消費(fèi)者剩余Figure3HowthePriceAffects

ConsumerSurplusInitialconsumersurplusQuantity(b)ConsumerSurplusatPricePPrice0DemandABCDEFP1Q1P2Q2ConsumersurplustonewconsumersAdditionalconsumersurplustoinitialconsumersQ2P2圖3.價(jià)格如何影響消費(fèi)者剩余數(shù)量?jī)r(jià)格0需求原來(lái)的消費(fèi)者剩余原來(lái)消費(fèi)者新增的消費(fèi)者剩余新消費(fèi)者的消費(fèi)者剩余Q1P1DEFBCA（b）價(jià)格在P2時(shí)的消費(fèi)者剩余WhatDoesConsumerSurplusMeasure?Consumersurplus,

theamountthatbuyersarewillingtopayforagoodminustheamounttheyactuallypayforit,measuresthebenefitthatbuyersreceivefromagoodasthebuyersthemselvesperceiveit.消費(fèi)者剩余衡量了什么？消費(fèi)者剩余，

即買(mǎi)者愿意為一種物品支付的量減他們實(shí)際支付的量，衡量了消費(fèi)者從一種物品中得到的買(mǎi)者自己感覺(jué)到的利益。ProducerSurplus生產(chǎn)者剩余Producersurplusistheamountasellerispaidminustheseller’scost.

生產(chǎn)者剩余——賣(mài)者得到的量減去賣(mài)者的成本。Itmeasuresthebenefittosellersparticipatinginamarket.

它衡量了賣(mài)者從參與市場(chǎng)中得到的利益。TheCostsofFourPossibleSellers...

四個(gè)可能賣(mài)者的成本…UsingtheSupplyCurvetoMeasureProducerSurplus

利用供給曲線(xiàn)衡量生產(chǎn)者剩余Justasconsumersurplusisrelatedtothedemandcurve,producersurplusiscloselyrelatedtothesupplycurve.

正如消費(fèi)者剩余與需求曲線(xiàn)密切相關(guān)一樣，生產(chǎn)者剩余也與供給曲線(xiàn)緊密相關(guān)。TheSupplyScheduleandtheSupplyCurve供給表和供給曲線(xiàn)TheSupplyScheduleandtheSupplyCurve

供給表和供給曲線(xiàn)QuantityofHousesPainted要油漆的房子數(shù)量PriceofHousePainting油漆房子的價(jià)格500800$90006001234Grandma’scost格拉瑪?shù)某杀綠eorgia’scost喬治亞的成本Frida’scost路易斯的成本

Mary’scost瑪麗的成本Supply供給Theareabelowthepriceandabovethesupplycurvemeasurestheproducersurplusinamarket.價(jià)格以下和供給曲線(xiàn)以上的面積衡量市場(chǎng)的生產(chǎn)者剩余。UsingtheSupplyCurvetoMeasureProducerSurplus

用供給曲線(xiàn)衡量生產(chǎn)者剩余MeasuringProducerSurpluswith

theSupplyCurve...QuantityofHousesPaintedPriceofHousePainting500800$90006001234SupplyGrandma’sproducersurplus($100)Price=$600用供給曲線(xiàn)衡量生產(chǎn)者剩余...要油漆的房子數(shù)量油漆房子的價(jià)格500800$90006001234供給格拉瑪?shù)纳a(chǎn)者剩余（100美元）價(jià)格=600美元MeasuringProducerSurpluswith

theSupplyCurve...QuantityofHousesPaintedPriceofHousePainting500800$90006001234SupplyGrandma’sproducersurplus($300)Price=$800Georgia’sproducersurplus($200)Totalproducersurplus($500)用供給曲線(xiàn)衡量生產(chǎn)者剩余...要油漆房子的數(shù)量油漆房子的價(jià)格500800$90006001234供給格拉瑪?shù)纳a(chǎn)者剩余（300美元）價(jià)格=800美元喬治亞的生產(chǎn)者剩余（100美元）總生產(chǎn)者剩余(500美元)Figure6HowthePriceAffects

ProducerSurplusCopyright?2003Southwestern/ThomsonLearningProducersurplusQuantity(a)ProducerSurplusatPriceP

Price0SupplyBACQ1P1圖6.價(jià)格如何影響生產(chǎn)者剩余Copyright?2003Southwestern/ThomsonLearning生產(chǎn)者剩余數(shù)量(a)價(jià)格在P

價(jià)格0供給BACQ1P1時(shí)的生產(chǎn)者剩余Figure6HowthePriceAffects

ProducerSurplusCopyright?2003Southwestern/ThomsonLearningQuantity(b)ProducerSurplusatPriceP

Price0P1BCSupplyAInitialproducersurplusQ1P2Q2ProducersurplustonewproducersAdditionalproducersurplustoinitialproducersDEF圖6.價(jià)格如何影響生產(chǎn)者剩余Copyright?2003Southwestern/ThomsonLearning數(shù)量(b)價(jià)格在P

價(jià)格0P1BC供給A原來(lái)的生產(chǎn)者剩余Q1P2Q2新生產(chǎn)者的生產(chǎn)者剩余原來(lái)生產(chǎn)者新增的生產(chǎn)者剩余DEF時(shí)的生產(chǎn)者剩余MarketEfficiency市場(chǎng)效率

Consumersurplusandproducersurplusmaybeusedtoaddressthefollowingquestion:消費(fèi)者剩余和生產(chǎn)者剩余可以用來(lái)回答下面問(wèn)題：Istheallocationofresourcesdeterminedbyfreemarketsinanywaydesirable?由自由市場(chǎng)決定的資源配置是以一種合意的方式進(jìn)行的嗎？MARKETEFFICIENCYandConsumerSurplus=Valuetobuyers_AmountpaidbybuyersProducerSurplus=Amountreceivedbysellers_Costtosellers市場(chǎng)效率和消費(fèi)者剩余=買(mǎi)者的評(píng)價(jià)_買(mǎi)者支付的量生產(chǎn)者剩余=賣(mài)者得到的量_賣(mài)者的成本MARKETEFFICIENCYorTotalSurplus=Valueto

buyers_CosttosellersTotalSurplus=ConsumerSurplusProducerSurplus+市場(chǎng)效率或總剩余=買(mǎi)者的評(píng)價(jià)_賣(mài)者的成本總剩余=消費(fèi)者剩余生產(chǎn)者剩余+MarketEfficiency市場(chǎng)效率Marketefficiency

isthepropertyofaresourceallocationofmaximizingthetotalsurplusreceivedbyallmembersofsociety.市場(chǎng)效率——資源配置使社會(huì)所有成員得到的總剩余最大化的性質(zhì)。MarketEfficiency市場(chǎng)效率Inadditiontomarketefficiency,asocialplannermightalsocareabout

equity

–thefairnessofthedistributionofwell-beingamongthevariousbuyersandsellers.除了效率之外，社會(huì)計(jì)劃者還應(yīng)關(guān)心平等——福利在各種買(mǎi)者與賣(mài)者之間分配的公平性。ConsumerandProducerSurplusintheMarketEquilibrium...PriceEquilibriumprice0QuantityEquilibriumquantityASupplyCBDemandDEProducersurplusConsumersurplus市場(chǎng)均衡時(shí)的消費(fèi)者與生產(chǎn)者剩余...價(jià)格均衡價(jià)格0數(shù)量均衡數(shù)量A供給CB需求DE生產(chǎn)者剩余消費(fèi)者剩余ThreeInsightsConcerningMarketOutcomesFreemarketsallocatethesupplyofgoodstothebuyerswhovaluethemmosthighly.Freemarketsallocatethedemandforgoodstothesellerswhocanproducethematleastcost.Freemarketsproducethequantityofgoodsthatmaximizesthesumofconsumerandproducersurplus.三種關(guān)于市場(chǎng)結(jié)果的觀(guān)點(diǎn)自由市場(chǎng)把物品的供給分配給對(duì)這些物品評(píng)價(jià)最高的買(mǎi)者。自由市場(chǎng)把物品的需求分配給可以以最低成本生產(chǎn)這些物品的賣(mài)者。自由市場(chǎng)生產(chǎn)使消費(fèi)者和生產(chǎn)者總剩余最大化的產(chǎn)量。Price0QuantityEquilibriumquantitySupplyDemandCosttosellersValuetobuyersValuetobuyers

CosttosellersValuetobuyersisgreaterthancosttosellers.Valuetobuyersislessthancosttosellers.TheEfficiencyoftheEquilibriumQuantity價(jià)格0數(shù)量均衡數(shù)量供給需求賣(mài)者的成本買(mǎi)者的評(píng)價(jià)買(mǎi)者的評(píng)價(jià)賣(mài)者的成本買(mǎi)者的評(píng)價(jià)大于賣(mài)者的成本買(mǎi)者的評(píng)價(jià)小于賣(mài)者的成本均衡數(shù)量的效率EvaluatingtheMarketEquilibriumBecausetheequilibriumoutcomeisanefficientallocationofresources,thesocialplannercanleavethemarketoutcomeashe/shefindsit.ThispolicyofleavingwellenoughalonegoesbytheFrenchexpression

laissezfaire.評(píng)價(jià)市場(chǎng)均衡因?yàn)榫饨Y(jié)果是資源的有效配置，所以社會(huì)計(jì)劃者可以讓市場(chǎng)自己找到結(jié)果。

這種完全放開(kāi)的政策可以用法語(yǔ)“自由放任”來(lái)表述，這句話(huà)字面上的含義是“讓他們自由行事吧”。MarketPowerIfamarketsystemisnotperfectlycompetitive,marketpowermayresult.Marketpoweristheabilitytoinfluenceprices.Marketpowercancausemarketstobeinefficientbecauseitkeepspriceandquantityfromtheequilibriumof supplyanddemand.市場(chǎng)勢(shì)力如果一個(gè)市場(chǎng)系統(tǒng)不是完全競(jìng)爭(zhēng)的，就會(huì)出現(xiàn)市場(chǎng)勢(shì)力。市場(chǎng)勢(shì)力是影響市場(chǎng)價(jià)格的能力。市場(chǎng)勢(shì)力可以使市場(chǎng)無(wú)效率，因?yàn)樗箖r(jià)格和數(shù)量背離供求均衡。ExternalitiesExternalities

arecreatedwhenamarketoutcomeaffectsindividualsotherthanbuyersandsellersinthatmarket.Externalitiescausewelfareinamarketto dependonmorethanjustthevaluetothebuyersandcosttothesellers.Whenbuyersandsellersdonottakeexternalitiesintoaccountwhendecidinghowmuchtoconsumeandproduce,theequilibriuminthemarketcanbeinefficient.外部性外部性——當(dāng)某一市場(chǎng)結(jié)果影響根本不參與此市場(chǎng)的人時(shí)，外部性就產(chǎn)生了。外部性使市場(chǎng)福利還要取決于買(mǎi)者評(píng)價(jià)和賣(mài)者成本之外的因素。在買(mǎi)者決定消費(fèi)量和賣(mài)者決定生產(chǎn)量而不考慮外部性時(shí)，市場(chǎng)均衡可能是無(wú)效率的。SummaryConsumersurplusequalsbuyers’willingnesstopayforagoodminustheamounttheyactuallypayforit.Consumersurplusmeasuresthebenefitbuyersgetfromparticipatinginamarket.Consumersurpluscanbecomputedbyfindingtheareabelowthedemandcurveandabovetheprice.小結(jié)消費(fèi)者剩余等于買(mǎi)者對(duì)某種物品的支付意