andMarketDemand(微观经济学-华侨大学,JeffCaldw

,Chapter4,IndividualandMarketDemand,Chapter4,Slide2,TopicstobeDiscussed,IndividualDemandIncomeandSubstitutionEffectsMarketDemandConsumerSurplus,Chapter4,Slide3,TopicstobeDiscussed,NetworkExternalitiesEmpiricalEstimationofDemand,Chapter4,Slide4,IndividualDemand,PriceChangesUsingthefiguresdevelopedinthepreviouschapter,theimpactofachangeinthepriceoffoodcanbeillustratedusingindifferencecurves.,Chapter4,Slide5,EffectofaPriceChange,Food(unitspermonth),Clothing(unitspermonth),Chapter4,Slide6,Price-ConsumptionCurve,EffectofaPriceChange,Food(unitspermonth),Clothing(unitspermonth),4,5,6,U2,U3,A,B,D,U1,4,12,20,Theprice-consumptioncurvetracesouttheutilitymaximizingmarketbasketforthevariouspricesforfood.,Chapter4,Slide7,EffectofaPriceChange,Food(unitspermonth),PriceofFood,Chapter4,Slide8,IndividualDemand,TwoImportantPropertiesofDemandCurves1)Thelevelofutilitythatcanbeattainedchangesaswemovealongthecurve.,TheIndividualDemandCurve,Chapter4,Slide9,IndividualDemand,TwoImportantPropertiesofDemandCurves2)Ateverypointonthedemandcurve,theconsumerismaximizingutilitybysatisfyingtheconditionthattheMRSoffoodforclothingequalstheratioofthepricesoffoodandclothing.,TheIndividualDemandCurve,Chapter4,Slide10,EffectofaPriceChange,Food(unitspermonth),PriceofFood,Chapter4,Slide11,IndividualDemand,IncomeChangesUsingthefiguresdevelopedinthepreviouschapter,theimpactofachangeintheincomecanbeillustratedusingindifferencecurves.,Chapter4,Slide12,EffectsofIncomeChanges,Food(unitspermonth),Clothing(unitspermonth),Anincreaseinincome,withthepricesfixed,causesconsumerstoaltertheirchoiceofmarketbasket.,Assume:Pf=$1Pc=$2I=$10,$20,$30,Chapter4,Slide13,EffectsofIncomeChanges,Food(unitspermonth),Priceoffood,Anincreaseinincome,from$10to$20to$30,withthepricesfixed,shiftstheconsumersdemandcurvetotheright.,Chapter4,Slide14,IndividualDemand,IncomeChangesTheincome-consumptioncurvetracesouttheutility-maximizingcombinationsoffoodandclothingassociatedwitheveryincomelevel.,Chapter4,Slide15,IndividualDemand,IncomeChangesAnincreaseinincomeshiftsthebudgetlinetotheright,increasingconsumptionalongtheincome-consumptioncurve.Simultaneously,theincreaseinincomeshiftsthedemandcurvetotheright.,Chapter4,Slide16,IndividualDemand,IncomeChangesWhentheincome-consumptioncurvehasapositiveslope:Thequantitydemandedincreaseswithincome.Theincomeelasticityofdemandispositive.Thegoodisanormalgood.,NormalGoodvs.InferiorGood,Chapter4,Slide17,IndividualDemand,IncomeChangesWhentheincome-consumptioncurvehasanegativeslope:Thequantitydemandeddecreaseswithincome.Theincomeelasticityofdemandisnegative.Thegoodisaninferiorgood.,NormalGoodvs.InferiorGood,Chapter4,Slide18,AnInferiorGood,Hamburger(unitspermonth),Steak(unitspermonth),Chapter4,Slide19,IndividualDemand,EngelCurvesEngelcurvesrelatethequantityofgoodconsumedtoincome.Ifthegoodisanormalgood,theEngelcurveisupwardsloping.Ifthegoodisaninferiorgood,theEngelcurveisdownwardsloping.,Chapter4,Slide20,EngelCurves,Food(unitspermonth),30,4,8,12,10,Income($permonth),20,16,0,Chapter4,Slide21,EngelCurves,Food(unitspermonth),30,4,8,12,10,Income($permonth),20,16,0,ConsumerExpendituresintheUnitedStates,Entertainment70094712741514205426544300OwnedDwellings1116172522533243445457939898RentedDwellings1957217023712536213715401266HealthCare1031169719181820205222142642Food2656338541094888542962208279Clothing85997813631772177826143442,ExpenditureLessthan1,000-20,000-30,000-40,000-50,000-70,000-($)on:$10,00019,00029,00039,00049,00069,000andabove,IncomeGroup(1997$),Chapter4,Slide23,IndividualDemand,1)Twogoodsareconsideredsubstitutesifanincrease(decrease)inthepriceofoneleadstoanincrease(decrease)inthequantitydemandedoftheother.e.g.movieticketsandvideorentals,SubstitutesandComplements,Chapter4,Slide24,IndividualDemand,2)Twogoodsareconsideredcomplementsifanincrease(decrease)inthepriceofoneleadstoadecrease(increase)inthequantitydemandedoftheother.e.g.gasolineandmotoroil,SubstitutesandComplements,Chapter4,Slide25,IndividualDemand,3)Twogoodsareindependentwhenachangeinthepriceofonegoodhasnoeffectonthequantitydemandedoftheother,SubstitutesandComplements,Chapter4,Slide26,IndividualDemand,SubstitutesandComplementsIfthepriceconsumptioncurveisdownward-sloping,thetwogoodsareconsideredsubstitutes.Ifthepriceconsumptioncurveisupward-sloping,thetwogoodsareconsideredcomplements.Theycouldbeboth!,Chapter4,Slide27,IncomeandSubstitutionEffects,Afallinthepriceofagoodhastwoeffects:Substitution&IncomeSubstitutionEffectConsumerswilltendtobuymoreofthegoodthathasbecomerelativelycheaper,andlessofthegoodthatisnowrelativelymoreexpensive.,Chapter4,Slide28,IncomeandSubstitutionEffects,Afallinthepriceofagoodhastwoeffects:Substitution&IncomeIncomeEffectConsumersexperienceanincreaseinrealpurchasingpowerwhenthepriceofonegoodfalls.,Chapter4,Slide29,IncomeandSubstitutionEffects,SubstitutionEffectThesubstitutioneffectisthechangeinanitemsconsumptionassociatedwithachangeinthepriceoftheitem,withthelevelofutilityheldconstant.Whenthepriceofanitemdeclines,thesubstitutioneffectalwaysleadstoanincreaseinthequantityoftheitemdemanded.,Chapter4,Slide30,IncomeandSubstitutionEffects,IncomeEffectTheincomeeffectisthechangeinanitemsconsumptionbroughtaboutbytheincreaseinpurchasingpower,withthepriceoftheitemheldconstant.Whenapersonsincomeincreases,thequantitydemandedfortheproductmayincreaseordecrease.,Chapter4,Slide31,IncomeandSubstitutionEffects,IncomeEffectEvenwithinferiorgoods,theincomeeffectisrarelylargeenoughtooutweighthesubstitutioneffect.,Chapter4,Slide32,IncomeandSubstitutionEffects:NormalGood,Food(unitspermonth),O,Clothing(unitspermonth),Chapter4,Slide33,Food(unitspermonth),O,R,Clothing(unitspermonth),F1,S,F2,T,A,U1,E,SubstitutionEffect,D,IncomeandSubstitutionEffects:InferiorGood,Chapter4,Slide34,IncomeandSubstitutionEffects,ASpecialCase-TheGiffenGoodTheincomeeffectmaytheoreticallybelargeenoughtocausethedemandcurveforagoodtoslopeupward.Thisrarelyoccursandisoflittlepracticalinterest.,Chapter4,Slide35,EffectofaGasolineTaxWithaRebate,AssumePed=-0.5Income=$9,000Priceofgasoline=$1,Chapter4,Slide36,EffectofaGasolineTaxWithaRebate,GasolineConsumption(gallons/year),ExpendituresOnOtherGoods($),Chapter4,Slide37,MarketDemand,MarketDemandCurvesAcurvethatrelatesthequantityofagoodthatallconsumersinamarketbuytothepriceofthatgood.,FromIndividualtoMarketDemand,Chapter4,Slide38,DeterminingtheMarketDemandCurve,161016322481325326101840471150246,PriceIndividualAIndividualBIndividualCMarket($)(units)(units)(units)(units),Chapter4,Slide39,SummingtoObtainaMarketDemandCurve,Quantity,1,2,3,4,Price,0,5,5,10,15,20,25,30,Chapter4,Slide40,MarketDemand,TwoImportantPoints1)Themarketdemandwillshifttotherightasmoreconsumersenterthemarket.2)Factorsthatinfluencethedemandsofmanyconsumerswillalsoaffectthemarketdemand.,Chapter4,Slide41,MarketDemand,ElasticityofDemandRecall:Priceelasticityofdemandmeasuresthepercentagechangeinthequantitydemandedresultingfroma1-percentchangeinprice.,Chapter4,Slide42,PriceElasticityandConsumerExpenditure,DemandIfPriceIncreases,IfPriceDecreases,Expenditures:Expenditures:,Inelastic(Ep1)DecreaseIncrease,Chapter4,Slide43,MarketDemand,PointElasticityofDemandForlargepricechanges(e.g.20%),thevalueofelasticitywilldependuponwherethepriceandquantitylieonthedemandcurve.,Chapter4,Slide44,MarketDemand,PointElasticityofDemandPointelasticitymeasureselasticityatapointonthedemandcurve.Itsformulais:,Chapter4,Slide45,MarketDemand,ProblemsUsingPointElasticityWemayneedtocalculatepriceelasticityoverportionofthedemandcurveratherthanatasinglepoint.Thepriceandquantityusedasthebasewillalterthepriceelasticityofdemand.,Chapter4,Slide46,MarketDemand,AssumePriceincreasesfrom8$to$10quantitydemandedfallsfrom6to4Percentchangeinpriceequals:$2/$8=25%or$2/$10=20%Percentchangeinquantityequals:-2/6=-33.33%or-2/4=-50%,PointElasticityofDemand(AnExample),Chapter4,Slide47,MarketDemand,Elasticityequals:-33.33/.25=-1.33or-.50/.20=-2.54Whichoneiscorrect?,PointElasticityofDemand(AnExample),Chapter4,Slide48,MarketDemand,ArcElasticityofDemandArcelasticitycalculateselasticityoverarangeofpricesItsformulais:,Chapter4,Slide49,MarketDemand,ArcElasticityofDemand(AnExample),Chapter4,Slide50,TheAggregateDemandForWheat,ThedemandforU.S.wheatiscomprisedofdomesticdemandandexportdemand.,AnExample:,Chapter4,Slide51,TheAggregateDemandForWheat,Thedomesticdemandforwheatisgivenbytheequation:QDD=1700-107PTheexportdemandforwheatisgivenbytheequation:QDE=1544-176P,Chapter4,Slide52,TheAggregateDemandForWheat,Domesticdemandisrelativelypriceinelastic(-0.2),whileexportdemandismorepriceelastic(-0.4).,Chapter4,Slide53,TheAggregateDemandForWheat,Wheat(millionbushels/yr.),Price($/bushel),0,2,4,6,8,10,12,14,16,18,20,1000,2000,3000,4000,Chapter4,Slide54,ConsumerSurplus,ConsumerSurplusThedifferencebetweenthemaximumamountaconsumeriswillingtopayforagoodandtheamountactuallypaid.,Chapter4,Slide55,ConsumerSurplus6+5+4+3+2+1=21,ConsumerSurplus,RockConcertTickets,Price($perticket),2,3,4,5,6,13,0,1,14,15,16,17,18,19,20,Chapter4,Slide56,ConsumerSurplus,Thestepladderdemandcurvecanbeconvertedintoastraight-linedemandcurvebymakingtheunitsofthegoodsmaller.,Chapter4,Slide57,ConsumerSurplusfortheMarketDemand,ConsumerSurplus,RockConcertTickets,Price($perticket),2,3,4,5,6,13,0,1,14,15,16,17,18,19,20,Chapter4,Slide58,ConsumerSurplus,Combiningconsumersurpluswiththeaggregateprofitsthatproducersobtainwecanevaluate:1)Costsandbenefitsofdifferentmarketstructures2)Publicpoliciesthatalterthebehaviorofconsumersandfirms,Chapter4,Slide59,TheValueofCleanAir,Airisfreeinthesensethatwedontpaytobreatheit.TheCleanAirActwasamendedin1970.Question:Werethebenefitsofcleaninguptheairworththecosts?,AnExample:,Chapter4,Slide60,TheValueofCleanAir,Peoplepaymoretobuyhouseswheretheairisclean.DataforhousepricesamongneighborhoodsofBostonandLosAngeleswerecomparedwiththevariousairpollutants.,Chapter4,Slide61,ValuingCleanerAir,Chapter4,Slide62,NetworkExternalities,Uptothispointwehaveassumedthatpeoplesdemandsforagoodareindependentofoneanother.Iffact,apersonsdemandmaybeaffectedbythenumberofotherpeoplewhohavepurchasedthegood.,Chapter4,Slide63,NetworkExternalities,Ifthisisthecase,anetworkexternalityexists.Networkexternalitiescanbepositiveornegative.,Chapter4,Slide64,NetworkExternalities,Apositivenetworkexternalityexistsifthequantityofagooddemandedbyaconsumerincreasesinresponsetoanincreaseinpurchasesbyotherconsumers.Negativenetworkexternalitiesarejusttheopposite.,Chapter4,Slide65,NetworkExternalities,TheBandwagonEffectThisisthedesiretobeinstyle,tohaveagoodbecausealmosteveryoneelsehasit,ortoindulgeinafad.Thisisthemajorobjectiveofmarketingandadvertisingcampaigns(e.g.toys,clothing).,Chapter4,Slide66,PositiveNetworkExternality:BandwagonEffect,Quantity(thousandspermonth),Price($perunit),Chapter4,Slide67,Demand,PositiveNetworkExternality:BandwagonEffect,Quantity(thousandspermonth),Price($perunit),D20,20,40,60,80,100,D40,D60,D80,D100,Themarketdemandcurveisfoundbyjoiningthepointsontheindividualdemandcurves.Itisrelativelymoreelastic.,Chapter4,Slide68,Demand,PositiveNetworkExternality:BandwagonEffect,Quantity(thousandspermonth),Price($perunit),D20,20,40,60,80,100,D40,D60,D80,D100,PurePriceEffect,48,Supposethepricefallsfrom$30to$20.Iftherewerenobandwagoneffect,quantitydemandedwouldonlyincreaseto48,000,$20,$30,Chapter4,Slide69,Demand,PositiveNetworkExternality:BandwagonEffect,Quantity(thousandspermonth),Price($perunit),D20,20,40,60,80,100,D40,D60,D80,D100,PurePriceEffect,$20,48,BandwagonEffect,Butasmorepeoplebuythegood,itbecomesstylishtoownitandthequantitydemandedincreasesfurther.,$30,Chapter4,Slide70,NetworkExternalities,TheSnobEffectIfthenetworkexternalityisnegative,asnobeffectexists.Thesnobeffectreferstothedesiretoownexclusiveoruniquegoods.Thequantitydemandedofa“snob”goodishigherthefewerthepeoplewhoownit.,Chapter4,Slide71,NegativeNetworkExternality:SnobEffect,Quantity(thousandspermonth),Price($perunit),Chapter4,Slide72,NegativeNetworkExternality:SnobEffect,Quantity(thousandspermonth),2,4,6,8,Thedemandislesselasticandasasnobgooditsvalueisgreatlyreducedifmorepeopleownit.Salesdecreaseasaresult.Examples:Rolexwatchesandlonglinesattheskilift.,Price($perunit),D2,$30,000,$15,000,14,D4,D6,D8,Demand,PurePriceEffect,SnobEffect,NetEffect,Chapter4,Slide73,NetworkExternalitiesandtheDemandsforComputersandFaxMachines,ExamplesofPositiveFeedbackExternalitiesMainframecomputers:1954-1965MicrosoftWindowsPCoperatingsystemFax-machinesande-mail,Chapter4,Slide74,EmpiricalEstimationofDemand,Themostdirectwaytoobtaininformationaboutdemandisthroughinterviewswhereconsumersareaskedhowmuchofaproducttheywouldbewillingtobuyatagivenprice.,Chapter4,Slide75,EmpiricalEstimationofDemand,ProblemConsumersmaylackinformationorinterest,orbemisleadbytheinterviewer.,Chapter4,Slide76,Indirectmarketingexperiments,actualsalesoffersareposedtopotentialcustomersandtheresponsesofcustomersareobserved.,EmpiricalEstimationofDemand,Chapter4,Slide77,TheStatisticalApproachtoDemandEstimationProperlyapplied,thestatisticalapproachtodemandestimationcanenableonetosortouttheeffectsofvariablesonthequantitydemandedofaproduct.“Least-squares”regressionisoneapproach.,EmpiricalEstimationofDemand,Chapter4,Slide78,YearQuantity(Q)Price(P)Income(I),DemandDataforRaspberries,1988424101989720101990817101991131717199216101719931515171994191220199520920199622520,Chapter4,Slide79,Assumingonlypricedeterminesdemand:Q=a-bPQ=28.2-1.00P,EmpiricalEstimationofDemand,Chapter4,Slide80,EstimatingDemand,Quantity,Price,0,5,10,15,20,25,15,10,5,25,20,Chapter4,Slide81,EstimatingDemand,Adjustingforchangesinincome,Chapter4,Slide82,Forthedemandequation:Q=a-bPElasticity:,EmpiricalEstimationofDemand,EstimatingElasticities,Chapter4,Slide83,Assuming:Price&incomeelasticityareconstantTheisoelasticdemand=Theslope,-b=priceelasticityofdemandConstant,c=incomeelasticity,EmpiricalEstimationofDemand,EstimatingElasticities,Chapter4,Slide84,UsingtheRaspberrydata:Priceelasticity=-0.24(Inelastic)Incomeelasticity=1.46,EmpiricalEstimationofDemand,EstimatingElasticities,Chapter4,Sli