经济学原理Chap07曼昆.ppt

Consumers Producers andtheEfficiencyofMarkets Chapter7 Copyright 2001byHarcourt Inc Allrightsreserved Requestsforpermissiontomakecopiesofanypartoftheworkshouldbemailedto PermissionsDepartment HarcourtCollegePublishers 6277SeaHarborDrive Orlando Florida32887 6777 RevisitingtheMarketEquilibrium Dotheequilibriumpriceandquantitymaximizethetotalwelfareofbuyersandsellers Marketequilibriumreflectsthewaymarketsallocatescarceresources Whetherthemarketallocationisdesirableisdeterminedbywelfareeconomics WelfareEconomics Welfareeconomicsisthestudyofhowtheallocationofresourcesaffectseconomicwell being Buyersandsellersreceivebenefitsfromtakingpartinthemarket Theequilibriuminamarketmaximizesthetotalwelfareofbuyersandsellers WelfareEconomics Equilibriuminthemarketresultsinmaximumbenefits andthereforemaximumtotalwelfareforboththeconsumersandtheproducersoftheproduct WelfareEconomics Consumersurplusmeasureseconomicwelfarefromthebuyer sside Producersurplusmeasureseconomicwelfarefromtheseller sside ConsumerSurplus Willingnesstopayisthemaximumpricethatabuyeriswillingandabletopayforagood Itmeasureshowmuchthebuyervaluesthegoodorservice ConsumerSurplus Consumersurplusistheamountabuyeriswillingtopayforagoodminustheamountthebuyeractuallypaysforit FourPossibleBuyers WillingnesstoPay ConsumerSurplus Themarketdemandcurvedepictsthevariousquantitiesthatbuyerswouldbewillingandabletopurchaseatdifferentprices FourPossibleBuyers WillingnesstoPay MeasuringConsumerSurpluswiththeDemandCurve PriceofAlbum 50 70 80 0 100 1 2 3 4 QuantityofAlbums MeasuringConsumerSurpluswiththeDemandCurve PriceofAlbum 50 70 80 0 100 1 2 3 4 QuantityofAlbums Demand Price 80 MeasuringConsumerSurpluswiththeDemandCurve PriceofAlbum 50 70 80 0 100 1 2 3 4 QuantityofAlbums Demand Price 70 MeasuringConsumerSurpluswiththeDemandCurve Theareabelowthedemandcurveandabovethepricemeasurestheconsumersurplusinthemarket HowthePriceAffectsConsumerSurplus Quantity Price 0 Demand Copyright 2001byHarcourt Inc Allrightsreserved Initialconsumersurplus ConsumerSurplusandEconomicWell Being Consumersurplus theamountthatbuyersarewillingtopayforagoodminustheamounttheyactuallypayforit measuresthebenefitthatbuyersreceivefromagoodasthebuyersthemselvesperceiveit ProducerSurplus Producersurplusistheamountasellerispaidminusthecostofproduction Itmeasuresthebenefittosellersparticipatinginamarket TheCostsofFourPossibleSellers ProducerSurplusandtheSupplyCurve Justasconsumersurplusisrelatedtothedemandcurve producersurplusiscloselyrelatedtothesupplycurve Atanyquantity thepricegivenbythesupplycurveshowsthecostofthemarginalseller thesellerwhowouldleavethemarketfirstifthepricewereanylower SupplySchedulefortheFourPossibleSellers ProducerSurplusandtheSupplyCurve QuantityofHousesPainted PriceofHousePainting 500 800 900 0 600 1 2 3 4 Supply Theareabelowthepriceandabovethesupplycurvemeasurestheproducersurplusinamarket ProducerSurplusandtheSupplyCurve MeasuringProducerSurpluswiththeSupplyCurve QuantityofHousesPainted PriceofHousePainting 500 800 900 0 600 1 2 3 4 Supply Price 600 MeasuringProducerSurpluswiththeSupplyCurve QuantityofHousesPainted PriceofHousePainting 500 800 900 0 600 1 2 3 4 Supply Price 800 HowPriceAffectsProducerSurplus Quantity Price 0 Supply InitialProducersurplus MarketEfficiency Consumersurplusandproducersurplusmaybeusedtoaddressthefollowingquestion Istheallocationofresourcesdeterminedbyfreemarketsinanywaydesirable EconomicWell BeingandTotalSurplus and EconomicWell BeingandTotalSurplus or MarketEfficiency Marketefficiencyisachievedwhentheallocationofresourcesmaximizestotalsurplus MarketEfficiency Inadditiontomarketefficiency asocialplannermightalsocareaboutequity thefairnessofthedistributionofwell beingamongthevariousbuyersandsellers EvaluatingtheMarketEquilibrium Price Equilibriumprice 0 Quantity Equilibriumquantity A Supply C B Demand D E ConsumerandProducerSurplusintheMarketEquilibrium Price Equilibriumprice 0 Quantity Equilibriumquantity A Supply C B Demand D E Producersurplus Consumersurplus ThreeInsightsConcerningMarketOutcomes Freemarketsallocatethesupplyofgoodstothebuyerswhovaluethemmosthighly Freemarketsallocatethedemandforgoodstothesellerswhocanproducethematleastcost Freemarketsproducethequantityofgoodsthatmaximizesthesumofconsumerandproducersurplus Price 0 Quantity Equilibriumquantity Supply Demand Costtosellers Valuetobuyers Valuetobuyers Costtosellers Valuetobuyersisgreaterthancosttosellers Valuetobuyersislessthancosttosellers TheEfficiencyoftheEquilibriumQuantity TheEfficiencyoftheEquilibriumQuantity Becausetheequilibriumoutcomeisanefficientallocationofresources thesocialplannercanleavethemarketoutcomeashe shefindsit ThispolicyofleavingwellenoughalonegoesbytheFrenchexpressionlaissezfaire MarketPower Ifamarketsystemisnotperfectlycompetitive marketpowermayresult Marketpoweristheabilitytoinfluenceprices Marketpowercancausemarketstobeinefficientbecauseitkeepspriceandquantityfromtheequilibriumofsupplyanddemand Externalities Externalitiesarecreatedwhenamarketoutcomeaffectsindividualsotherthanbuyersandsellersinthatmarket Externalitiescausewelfareinamarkettodependonmorethanjustthevaluetothebuyersandcosttothesellers Whenbuyersandsellersdonottakeexternalitiesintoaccountwhendecidinghowmuchtoconsumeandproduce theequilibriuminthemarketcanbeinefficient Summary Consumersurplusmeasuresthebenefitbuyersgetfromparticipatinginamarket Consumersurpluscanbecomputedbyfindingtheareabelowthedemandcurveandabovetheprice Summary Producersurplusmeasuresthebenefitsellersgetfromparticipatinginamarket Producersurpluscanbecomputedbyfindingtheareabelowthepriceandabovethesupplycurve Summary Theequilibriumofdemandandsupplymaximizesthesumofconsumerandproducersurplus Thisisasiftheinvisiblehandofthemarketplaceleadsbuyersandsellerstoallocateresourcesefficiently Marketsdonotallocateresourcesefficient