(1.7)-Chap07微观经济学课件

Consumers,Producers,andtheEfficiencyofMarketsChapter7RevisitingtheMarketEquilibriumDotheequilibriumpriceandquantitymaximizethetotalwelfareofbuyersandsellers? Marketequilibriumreflectsthewaymarketsallocatescarceresources.

Whetherthemarketallocationisdesirableisdeterminedbywelfareeconomics.WelfareEconomics

Welfareeconomics

isthestudyofhowtheallocationof

resourcesaffectseconomicwell-being.Buyersandsellersreceivebenefitsfromtakingpartinthemarket.Theequilibriuminamarketmaximizesthetotalwelfareofbuyersandsellers.WelfareEconomicsEquilibriuminthemarketresultsinmaximumbenefits,andthereforemaximumtotalwelfareforboththeconsumersandtheproducersoftheproduct.WelfareEconomicsConsumersurplusmeasureseconomicwelfarefromthebuyer’sside.Producersurplusmeasureseconomicwelfarefromtheseller’s

side.ConsumerSurplusWillingnesstopayisthemaximumpricethatabuyeriswillingandabletopayforagood.Itmeasureshowmuchthebuyervaluesthegoodorservice.ConsumerSurplusConsumersurplus

istheamountabuyeriswillingtopayforagoodminustheamountthebuyeractuallypaysforit.FourPossibleBuyers’WillingnesstoPay...ConsumerSurplusThemarketdemandcurvedepictsthevariousquantitiesthatbuyerswouldbewillingandabletopurchaseatdifferentprices.FourPossibleBuyers’WillingnesstoPay...MeasuringConsumerSurpluswiththeDemandCurve...PriceofAlbum5070800$1001234QuantityofAlbumsJohn’swillingnesstopayPaul’swillingnesstopayGeorge’swillingnesstopayRingo’swillingnesstopayDemandMeasuringConsumerSurpluswiththeDemandCurve...PriceofAlbum5070800$1001234QuantityofAlbumsDemandJohn’sconsumersurplus($20)Price=$80MeasuringConsumerSurpluswiththeDemandCurve...PriceofAlbum5070800$1001234QuantityofAlbumsDemandJohn’sconsumersurplus($30)Totalconsumersurplus($40)Price=$70Paul’sconsumersurplus($10)MeasuringConsumerSurpluswiththeDemandCurveTheareabelowthedemandcurveandabovethepricemeasurestheconsumersurplusinthemarket.Q2P2HowthePriceAffectsConsumerSurplus...QuantityPrice0DemandCopyright©2001byHarcourt,Inc.AllrightsreservedInitialconsumersurplusAdditionalconsumersurplustoinitialconsumersConsumersurplustonewconsumersQ1P1DEFBCAConsumerSurplusandEconomicWell-BeingConsumersurplus,

theamountthatbuyersarewillingtopayforagoodminustheamounttheyactuallypayforit,measuresthebenefitthatbuyersreceivefromagoodasthebuyersthemselvesperceiveit.ProducerSurplusProducersurplusistheamountasellerispaidminusthecostofproduction.Itmeasuresthebenefittosellersparticipatinginamarket.TheCostsofFourPossibleSellers...ProducerSurplusandtheSupplyCurveJustasconsumersurplusisrelatedtothedemandcurve,producersurplusiscloselyrelatedtothesupplycurve.Atanyquantity,thepricegivenbythesupplycurveshowsthecostofthemarginalseller,thesellerwhowouldleavethemarketfirstifthepricewereanylower.SupplySchedulefortheFourPossibleSellers...ProducerSurplusandthe

SupplyCurve...QuantityofHousesPaintedPriceofHousePainting500800$90006001234Grandma’scostGeorgia’scostFrida’scostMary’scostSupplyTheareabelowthepriceandabovethesupplycurvemeasurestheproducersurplusinamarket.ProducerSurplusandthe

SupplyCurveMeasuringProducerSurpluswiththeSupplyCurve...QuantityofHousesPaintedPriceofHousePainting500800$90006001234SupplyGrandma’sproducersurplus($100)Price=$600MeasuringProducerSurpluswiththeSupplyCurve...QuantityofHousesPaintedPriceofHousePainting500800$90006001234SupplyGrandma’sproducersurplus($300)Price=$800Georgia’sproducersurplus($200)Totalproducersurplus($500)P2Q2HowPriceAffectsProducerSurplus...QuantityPrice0SupplyQ1P1ABCInitialProducersurplusAdditionalproducersurplustoinitialproducersDEFProducersurplustonewproducersMarketEfficiencyConsumersurplusandproducersurplusmaybeusedtoaddressthefollowingquestion:Istheallocationofresourcesdeterminedbyfreemarketsinanywaydesirable?EconomicWell-BeingandTotalSurplusandConsumerSurplus=Valuetobuyers_AmountpaidbybuyersProducerSurplus=Amountreceivedbysellers_CosttosellersEconomicWell-BeingandTotalSurplusorTotalSurplus=Valueto

buyers_CosttosellersTotalSurplus=ConsumerSurplusProducerSurplus+MarketEfficiencyMarketefficiency

isachievedwhentheallocationofresourcesmaximizestotalsurplus.MarketEfficiencyInadditiontomarketefficiency,asocialplannermightalsocareabout

equity

–thefairnessofthedistributionofwell-beingamongthevariousbuyersandsellers.EvaluatingtheMarketEquilibrium...PriceEquilibriumprice0QuantityEquilibriumquantityASupplyCBDemandDEConsumerandProducerSurplusintheMarketEquilibrium...PriceEquilibriumprice0QuantityEquilibriumquantityASupplyCBDemandDEProducersurplusConsumersurplusThreeInsightsConcerningMarketOutcomesFreemarketsallocatethesupplyofgoodstothebuyerswhovaluethemmosthighly.Freemarketsallocatethedemandforgoodstothesellerswhocanproducethematleastcost.Freemarketsproducethequantityofgoodsthatmaximizesthesumofconsumerandproducersurplus.Price0QuantityEquilibriumquantitySupplyDemandCosttosellersValuetobuyersValuetobuyersCosttosellersValuetobuyersisgreaterthancosttosellers.Valuetobuyersislessthancosttosellers.TheEfficiencyoftheEquilibriumQuantityTheEfficiencyoftheEquilibriumQuantityBecausetheequilibriumoutcomeisanefficientallocationofresources,thesocialplannercanleavethemarketoutcomeashe/shefindsit.ThispolicyofleavingwellenoughalonegoesbytheFrenchexpression

laissezfaire.MarketPowerIfamarketsystemisnotperfectlycompetitive,marketpowermayresult.Marketpoweristheabilitytoinfluenceprices.Marketpowercancausemarketstobeinefficientbecauseitkeepspriceandquantityfromtheequilibriumof supplyanddemand.ExternalitiesExternalities

arecreatedwhenamarketoutcomeaffectsindividualsotherthanbuyersandsellersinthatmarket.Externalitiescausewelfareinamarketto dependonmorethanjustthevaluetothebuyersandcosttothesellers.Whenbuyersandsellersdonottakeexternalitiesintoaccountwhendecidinghowmuchtoconsumeandproduce,theequilibriuminthemarketcanbeinefficient.SummaryConsumersurplusmeasuresthebenefitbuyersgetfromparticipatinginamarket.Consumersurpluscanbecomputedbyfindingtheareabelowthedemandcurveandabovetheprice.SummaryProducersurplusmeasuresthebenefitsellersgetfromparticipatinginamarket.Producersurpluscanbecomputedbyfindingtheareabelowthepriceandabovethesupplycurve.SummaryTheequilibriumofdemandandsupplymaximizesthesumofconsumerandproducersurplus.Thisisasiftheinvisiblehandofthemarketplaceleadsbuyersandsellerstoallocateresourcesefficiently.Marketsdonotallocateresourcesefficientlyinthepresenceofmarketfailures.SummaryAnallocationofresourcesthatmaximizesthesumofconsumerandproducersurplusissaidtobeefficient.Policymakersareoftenconcernedwiththeefficiency,aswellastheequity,ofeconomicoutcomes.GraphicalReviewMeasuringConsumerSurpluswiththeDemandCurve...PriceofAlbum5070800$1001234QuantityofAlbumsJohn’swillingnesstopayPaul’swillingnesstopayGeorge’swillingnesstopayRingo’swillingnesstopayDemandMeasuringConsumerSurpluswiththeDemandCurve...PriceofAlbum5070800$1001234QuantityofAlbumsDemandJohn’sconsumersurplus($20)Price=$80MeasuringConsumerSurpluswiththeDemandCurve...PriceofAlbum5070800$1001234QuantityofAlbumsDemandJohn’sconsumersurplus($30)Totalconsumersurplus($40)Price=$70Paul’sconsumersurplus($10)HowthePriceAffectsConsumerSurplus...Q2P2QuantityPrice0DemandCopyright©2001byHarcourt,Inc.AllrightsreservedInitialconsumersurplusAdditionalconsumersurplustoinitialconsumersConsumersurplustonewconsumersQ1P1BCADEFProducerSurplusandthe

SupplyCurve...QuantityofHousesPaintedPriceofHousePainting500800$90006001234Grandma’scostGeorgia’scostFrida’scostMary’scostSupplyMeasuringProducerSurpluswiththeSupplyCurve...QuantityofHousesPaintedPriceofHousePainting500800$90006001234SupplyGrandma’sproducersurplus($100)Price=$