7consumers_producers 曼昆 微观经济学课件

3SUPPLYANDDEMANDII:MARKETSANDWELFARECopyright©2004South-Western7Consumers,Producers,andtheEfficiencyofMarketsCopyright©2004South-WesternREVISITINGTHEMARKETEQUILIBRIUM•Dotheequilibriumpriceandquantitymaximizethetotalwelfareofbuyersandsellers?•Marketequilibriumreflectsthewaymarketsallocatescarceresources.•Whetherthemarketallocationisdesirablecanbeaddressedbywelfareeconomics.Copyright©2004South-WesternWelfareEconomics•Welfareeconomicsisthestudyofhowtheallocationofresourcesaffectseconomicwell-being.•Buyersandsellersreceivebenefitsfromtakingpartinthemarket.•Theequilibriuminamarketmaximizesthetotalwelfareofbuyersandsellers.Copyright©2004South-WesternWelfareEconomics•Equilibriuminthemarketresultsinmaximumbenefits,andthereforemaximumtotalwelfareforboththeconsumersandtheproducersoftheproduct.Copyright©2004South-WesternWelfareEconomics•Consumersurplusmeasureseconomicwelfarefromthebuyer’sside.•Producersurplusmeasureseconomicwelfarefromtheseller’sside.Copyright©2004South-WesternCONSUMERSURPLUS•Willingnesstopayisthemaximumamountthatabuyerwillpayforagood.•Itmeasureshowmuchthebuyervaluesthegoodorservice.Copyright©2004South-WesternCONSUMERSURPLUS•Consumersurplusisthebuyer’swillingnesstopayforagoodminustheamountthebuyeractuallypaysforit.Table1FourPossibleBuyers’WillingnesstoPayCopyright©2004South-WesternCopyright©2004South-WesternCONSUMERSURPLUS•Themarketdemandcurvedepictsthevariousquantitiesthatbuyerswouldbewillingandabletopurchaseatdifferentprices.Copyright©2004South-WesternTheDemandScheduleandtheDemandCurveFigure1TheDemandScheduleandtheDemandCurveCopyright©2003Southwestern/ThomsonLearningPriceofAlbum0QuantityofAlbumsDemand1234$100John’swillingnesstopay80Paul’swillingnesstopay70George’swillingnesstopay50Ringo’swillingnesstopayFigure2MeasuringConsumerSurpluswiththeDemandCurveCopyright©2003Southwestern/ThomsonLearning(a)Price=$80PriceofAlbum5070800$100Demand1234QuantityofAlbumsJohn’sconsumersurplus($20)Figure2MeasuringConsumerSurpluswiththeDemandCurveCopyright©2003Southwestern/ThomsonLearning(b)Price=$70PriceofAlbum5070800$100Demand1234Totalconsumersurplus($40)QuantityofAlbumsJohn’sconsumersurplus($30)Paul’sconsumersurplus($10)Copyright©2004South-WesternUsingtheDemandCurvetoMeasureConsumerSurplus•Theareabelowthedemandcurveandabovethepricemeasurestheconsumersurplusinthemarket.Figure3HowthePriceAffectsConsumerSurplusCopyright©2003Southwestern/ThomsonLearningConsumersurplusQuantity(a)ConsumerSurplusatPricePPrice0DemandP1Q1BACFigure3HowthePriceAffectsConsumerSurplusCopyright©2003Southwestern/ThomsonLearningInitialconsumersurplusQuantity(b)ConsumerSurplusatPricePPrice0DemandABCDEFP1Q1P2Q2ConsumersurplustonewconsumersAdditionalconsumersurplustoinitialconsumersCopyright©2004South-WesternWhatDoesConsumerSurplusMeasure?•Consumersurplus,theamountthatbuyersarewillingtopayforagoodminustheamounttheyactuallypayforit,measuresthebenefitthatbuyersreceivefromagoodasthebuyersthemselvesperceiveit.Copyright©2004South-WesternPRODUCERSURPLUS•Producersurplusistheamountasellerispaidforagoodminustheseller’scost.•Itmeasuresthebenefittosellersparticipatinginamarket.Table2TheCostsofFourPossibleSellersCopyright©2004South-WesternCopyright©2004South-WesternUsingtheSupplyCurvetoMeasureProducerSurplus•Justasconsumersurplusisrelatedtothedemandcurve,producersurplusiscloselyrelatedtothesupplycurve.Copyright©2004South-WesternTheSupplyScheduleandtheSupplyCurveFigure4TheSupplyScheduleandtheSupplyCurveCopyright©2004South-WesternUsingtheSupplyCurvetoMeasureProducerSurplus•Theareabelowthepriceandabovethesupplycurvemeasurestheproducersurplusinamarket.Figure5MeasuringProducerSurpluswiththeSupplyCurveCopyright©2003Southwestern/ThomsonLearningQuantityofHousesPaintedPriceofHousePainting500800$90006001234(a)Price=$600SupplyGrandma’sproducersurplus($100)Figure5MeasuringProducerSurpluswiththeSupplyCurveCopyright©2003Southwestern/ThomsonLearningQuantityofHousesPaintedPriceofHousePainting500800$90006001234(b)Price=$800Georgia’sproducersurplus($200)Totalproducersurplus($500)Grandma’sproducersurplus($300)SupplyFigure6HowthePriceAffectsProducerSurplusCopyright©2003Southwestern/ThomsonLearningProducersurplusQuantity(a)ProducerSurplusatPricePPrice0SupplyBACQ1P1Figure6HowthePriceAffectsProducerSurplusCopyright©2003Southwestern/ThomsonLearningQuantity(b)ProducerSurplusatPricePPrice0P1BCSupplyAInitialproducersurplusQ1P2Q2ProducersurplustonewproducersAdditionalproducersurplustoinitialproducersDEFCopyright©2004South-WesternMARKETEFFICIENCY•Consumersurplusandproducersurplusmaybeusedtoaddressthefollowingquestion:•Istheallocationofresourcesdeterminedbyfreemarketsinanywaydesirable?Copyright©2004South-WesternMARKETEFFICIENCYConsumerSurplus=Valuetobuyers–AmountpaidbybuyersandProducerSurplus=Amountreceivedbysellers–CosttosellersCopyright©2004South-WesternMARKETEFFICIENCYTotalsurplus=Consumersurplus+ProducersurplusorTotalsurplus=Valuetobuyers–CosttosellersCopyright©2004South-WesternMARKETEFFICIENCY•Efficiencyisthepropertyofaresourceallocationofmaximizingthetotalsurplusreceivedbyallmembersofsoc