中级微观经济学范里安课件ch.ppt

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1、中级微观经济学15ChapterFifteenMarketDemand市场需求StructureFromIndividualtoMarketDemandFunctionsElasticitiesRevenueandown-priceelasticityofdemandMarginalrevenueandpriceelasticityFromIndividualtoMarketDemandFunctionsThinkofaneconomycontainingnconsumers,denotedbyi=1,…,n.Consumeri’sordinarydemandfunctionforcommo

2、dityjisFromIndividualtoMarketDemandFunctionsWhenallconsumersareprice-takers,themarketdemandfunctionforcommodityjisIfallconsumersareidenticalthenwhereM=nm.FromIndividualtoMarketDemandFunctionsThemarketdemandcurveisthe“horizontalsum”oftheindividualconsumers’demandcurves.E.g.supposethereareonlytwoc

3、onsumers;i=A,B.FromIndividualtoMarketDemandFunctionsp1p12015p1’p1”p1’p1”FromIndividualtoMarketDemandFunctionsp1p1p12015p1’p1”p1’p1”p1’FromIndividualtoMarketDemandFunctionsp1p1p12015p1’p1”p1’p1”p1’p1”FromIndividualtoMarketDemandFunctionsp1p1p1201535p1’p1”p1’p1”p1’p1”The“horizontalsum”ofthedemandcur

4、vesofindividualsAandB.Elasticities（弹性）Elasticitymeasuresthe“sensitivity”ofonevariablewithrespecttoanother.TheelasticityofvariableXwithrespecttovariableYisEconomicApplicationsofElasticityEconomistsuseelasticitiestomeasurethesensitivityofquantitydemandedofcommodityiwithrespecttothepriceofcommodityi(

5、own-priceelasticityofdemand，需求的自价格弹性)demandforcommodityiwithrespecttothepriceofcommodityj(cross-priceelasticityofdemand，需求的交叉价格弹性).EconomicApplicationsofElasticitydemandforcommodityiwithrespecttoincome(incomeelasticityofdemand需求的收入弹性)quantitysuppliedofcommodityiwithrespecttothepriceofcommodityi(own

6、-priceelasticityofsupply供给的自价格弹性)EconomicApplicationsofElasticityquantitysuppliedofcommodityiwithrespecttothewagerate(elasticityofsupplywithrespecttothepriceoflabor)andmany,manyothers.Own-PriceElasticityofDemandQ:Whynotuseademandcurve’sslopetomeasurethesensitivityofquantitydemandedtoachangeinacommo

7、dity’sownprice?Own-PriceElasticityofDemandX1*5501010slope=-2slope=-0.2p1p1InwhichcaseisthequantitydemandedX1*moresensitivetochangestop1?X1*Own-PriceElasticityofDemand5501010slope=-2slope=-0.2p1p1X1*X1*