微观经济学课件中英文05

,ElasticityandItsApplication弹性及其应用,Chapter5,Elasticity.弹性,isameasureofhowmuchbuyersandsellersrespondtochangesinmarketconditions.是衡量买者和卖者对市场条件变动的反应大小的指标。allowsustoanalyzesupplyanddemandwithgreaterprecision.使我们可以更精确地分析供给与需求,PriceElasticityofDemand,Priceelasticityofdemandisthepercentagechangeinquantitydemandedgivenapercentchangeintheprice.Itisameasureofhowmuchthequantitydemandedofagoodrespondstoachangeinthepriceofthatgood.,需求的价格弹性,需求的价格弹性价格变化1%引起的需求量的变化百分比值。它是一种物品的需求量对其价格变动的反应程度的衡量。,DeterminantsofPriceElasticityofDemand需求价格弹性的决定因素,NecessitiesversusLuxuries必需品与奢侈品AvailabilityofCloseSubstitutes相近替代品的可获得性DefinitionoftheMarket市场的定义TimeHorizon时间的长短,DeterminantsofPriceElasticityofDemand,Demandtendstobemoreelastic:ifthegoodisaluxury.thelongerthetimeperiod.thelargerthenumberofclosesubstitutes.themorenarrowlydefinedthemarket.,价格需求弹性的决定因素,需求倾向于富有弹性：如果物品是奢侈品时期更长相近替代品的数量更多市场定义的范围更窄,ComputingthePriceElasticityofDemand,Thepriceelasticityofdemandiscomputedasthepercentagechangeinthequantitydemandeddividedbythepercentagechangeinprice.,计算需求价格弹性,用需求量变动的百分比除以价格变动的百分比来计算需求价格弹性。,ComputingthePriceElasticityofDemand,Example:Ifthepriceofanicecreamconeincreasesfrom$2.00to$2.20andtheamountyoubuyfallsfrom10to8conesthenyourelasticityofdemandwouldbecalculatedas:,计算需求价格弹性,例子:如果冰激凌蛋卷的价格从2美元上升到2.2美元，你的购买量从10个下降到8个，你的需求价格弹性计算如下：,TheMidpointMethod:ABetterWaytoCalculatePercentageChangesandElasticities,Themidpointformulaispreferablewhencalculatingthepriceelasticityofdemandbecauseitgivesthesameanswerregardlessofthedirectionofthechange.,中点法:一种计算百分比变化和弹性的更好方法,中点法是计算需求价格弹性的更好方法，因为无论变动的方向如何，中点法给出了同一个答案。,TheMidpointMethod:ABetterWaytoCalculatePercentageChangesandElasticities,Example:Ifthepriceofanicecreamconeincreasesfrom$2.00to$2.20andtheamountyoubuyfallsfrom10to8conestheyourelasticityofdemand,usingthemidpointformula,wouldbecalculatedas:,中点法:一种计算百分比变化和弹性的更好方法,例子:如果冰激凌蛋卷的价格从2美元上升到2.2美元，你的购买量从10个下降到8个，利用中点法你的需求价格弹性计算如下：,TheVarietyofDemandCurves,InelasticDemandQuantitydemandeddoesnotrespondstronglytopricechanges.Priceelasticityofdemandislessthanone.ElasticDemandQuantitydemandedrespondsstronglytochangesinprice.Priceelasticityofdemandisgreaterthanone.,多种需求曲线,缺乏弹性的需求需求量不随着价格变化而强烈变化。需求价格弹性小于1。富有弹性的需求需求量随着价格变化而强烈变化。需求价格弹性大于1。,ComputingthePriceElasticityofDemand计算需求的价格弹性,Demandispriceelastic需求富有弹性,$5,4,Demand需求,Quantity数量,100,0,Price价格,50,TheVarietyofDemandCurves,PerfectlyInelasticQuantitydemandeddoesnotrespondtopricechanges.PerfectlyElasticQuantitydemandedchangesinfinitelywithanychangeinprice.UnitElasticQuantitydemandedchangesbythesamepercentageastheprice.,多种需求曲线,完全无弹性需求量不随价格变化而变化。完全弹性价格极小变化引起需求量极大变动。单位弹性需求量与价格同比例变动。,AVarietyofDemandCurves多种需求弹性曲线,Becausethepriceelasticityofdemandmeasureshowmuchquantitydemandedrespondstotheprice,itiscloselyrelatedtotheslopeofthedemandcurve.由于需求的价格弹性衡量需求量对价格变化的反应程度，所以它与需求曲线的斜率密切相关。,PerfectlyInelasticDemandElasticityequals0完全无弹性的需求弹性等于0,Quantity数量,Price价格,2.leavesthequantitydemandedunchanged.2.需求量不变。,InelasticDemandElasticityislessthan1缺乏弹性的需求弹性小于1,Quantity数量,Price价格,UnitElasticDemandElasticityequals1单位需求弹性弹性等于1,Quantity数量,Price价格,ElasticDemandElasticityisgreaterthan1富有弹性的需求弹性大于1,Quantity数量,Price价格,PerfectlyElasticDemand-Elasticityequalsinfinity,Quantity,Price,完全富有弹性弹性等于无穷大,数量,价格,TotalRevenueandthePriceElasticityofDemand总收益与需求价格弹性,Totalrevenueistheamountpaidbybuyersandreceivedbysellersofagood.总收益是一种物品买者的支付量和卖者得到的量。Computedasthepriceofthegoodtimesthequantitysold.用该物品的价格乘以销售量来计算。TR=PxQ,$4,Demand需求,Quantity数量,P,0,Price价格,PxQ=$400,(totalrevenue总收益),100,TotalRevenueandthePriceElasticityofDemand总收益与需求价格弹性,ElasticityandTotalRevenuealongaLinearDemandCurve沿着线性需求曲线的弹性与总收益,Withaninelasticdemandcurve,anincreaseinpriceleadstoadecreaseinquantitythatisproportionatelysmaller.Thus,totalrevenueincreases.如果需求是缺乏弹性的，价格上升导致需求量减少的比例小于价格上升的比例，所以总收益是增加的。,Figure3HowTotalRevenueChangesWhenPriceChanges:InelasticDemand,$3,Quantity,0,Price,80,Revenue=$240,Demand,$1,Demand,Quantity,0,Revenue=$100,100,Price,Anincreaseinpricefrom$1to$3.,leadstoanincreaseintotalrevenuefrom$100to$240,图3.总收益如何随着价格变化而变化：缺乏弹性的需求,$3,数量,0,价格,80,收益=240美元,需求,$1,需求,数量,0,收益=100美元,100,价格,价格从1美元上升到3美元.,导致总收益从100美元增加到240美元,ElasticityandTotalRevenuealongaLinearDemandCurve沿着线性需求曲线的弹性与总收益,Withanelasticdemandcurve,anincreaseinthepriceleadstoadecreaseinquantitydemandedthatisproportionatelylarger.Thus,totalrevenuedecreases.如果需求富有弹性，价格上升导致的需求量减少的比例大于价格上升的比例，因此总收益是减少的。,Figure4HowTotalRevenueChangesWhenPriceChanges:ElasticDemand,Demand,Quantity,0,Price,$4,50,Demand,Quantity,0,Price,Revenue=$100,$5,20,Anincreaseinpricefrom$4to$5.,leadstoadecreaseintotalrevenuefrom$200to$100,图4.总收益如何随着价格变化而变化：富有弹性的需求,需求,数量,0,价格,$4,50,数量,数量,0,价格,收益=100美元,$5,20,价格从4美元上升到5美元,导致总收益从200美元减少到100美元,theElasticityofaLinearDemandCurve,线性需求曲线的弹性,IncomeElasticityofDemand,Incomeelasticityofdemandmeasureshowmuchthequantitydemandedofagoodrespondstoachangeinconsumersincome.Itiscomputedasthepercentagechangeinthequantitydemandeddividedbythepercentagechangeinincome.,需求的收入弹性,需求的收入弹性衡量消费者收入变动时需求量如何变动。它是需求量变动的百分比除以收入变动的百分比。,ComputingIncomeElasticity计算收入弹性,需求量变动百分比,IncomeElasticity-TypesofGoods收入弹性：不同类型的物品,NormalGoods正常物品InferiorGoods劣等品Higherincomeraisesthequantitydemandedfornormalgoodsbutlowersthequantitydemandedforinferiorgoods.正常物品：收入提高增加需求量；劣等品：收入增加减少需求量。,IncomeElasticity-TypesofGoods-,GoodsconsumersregardasnecessitiestendtobeincomeinelasticExamplesincludefood,fuel,clothing,utilities,andmedicalservices.Goodsconsumersregardasluxuriestendtobeincomeelastic.Examplesincludesportscars,furs,andexpensivefoods.,收入弹性：不同类型的物品,消费者消费的必需品往往收入弹性小例如：食物、燃油、衣服、医疗服务。消费者消费的奢侈品往往收入弹性大例如：运动跑车、皮衣和昂贵物品。,需求的交叉价格弹性,替代品：E0互补品：E0无关物品：E0,PriceElasticityofSupply,Priceelasticityofsupplyisthepercentagechangeinquantitysuppliedresultingfromapercentchangeinprice.Itisameasureofhowmuchthequantitysuppliedofagoodrespondstoachangeinthepriceofthatgood.,供给的价格弹性,供给价格弹性价格变动1引起的供給量的变动百分比值。它是一种物品的供給量对其价格变动的反应程度的衡量。,PerfectlyInelasticSupplyElasticityequals0完全无弹性的供给：弹性等于0,Quantity数量,Price价格,2.leavesthequantitysuppliedunchanged.2.供給量不变。,InelasticSupplyElasticityislessthan1缺乏弹性的供给：弹性小于1,Quantity数量,Price价格,UnitElasticSupplyElasticityequals1单位弹性供给：弹性等于1,Quantity数量,Price价格,ElasticSupplyElasticityisgreaterthan1富有弹性的供给：弹性大于1,Quantity数量,Price价格,PerfectlyElasticSupplyElasticityequalsinfinity完全有弹性的供给：弹性等于无穷大,Quantity数量,Price价格,DeterminantsofElasticityofSupply,Abilityofsellerstochangetheamountofthegoodtheyproduce.Beach-frontlandisinelastic.Books,cars,ormanufacturedgoodsareelastic.Timeperiod.Supplyismoreelasticinthelongrun.,供给弹性的决定因素,卖者改变它们生产物品产量的能力海滩前的土地供给是缺乏弹性的。书、汽车或生产的物品供给是富有弹性的。时间长短供给在长期内更富有弹性。,ComputingthePriceElasticityofSupply,Thepriceelasticityofsupplyiscomputedasthepercentagechangeinthequantitysupplieddividedbythepercentagechangeinprice.,计算供给价格弹性,供给价格弹性等于供給量变动百分比除以价格变动百分比。,THREEAPPLICATIONSOFSUPPLY,DEMAND,ANDELASTICITY供给、需求与弹性的三个应用,Cangoodnewsforfarmingbebadnewsforfarmers?农业的好消息会是农民的坏消息吗？Whathappenstowheatfarmersandthemarketforwheatwhenuniversityagronomistsdiscoveranewwheathybridthatismoreproductivethanexistingvarieties?当大学的农业科学家培育出能比现有品种更高产的小麦新杂交品种时，种小麦的农民会怎么办？小麦市场又会发生什么变动呢？,THREEAPPLICATIONSOFSUPPLY,DEMAND,ANDELASTICITY供给、需求与弹性的三个应用,Examinewhetherthesupplyordemandcurveshifts.考察是供给曲线还是需求曲线移动。Determinethedirectionoftheshiftofthecurve.考虑曲线向哪个方向移动。Usethesupply-and-demanddiagramtoseehowthemarketequilibriumchanges.用供求图说明市场均衡如何变动。,3.andaproportionatelysmallerincreaseinquantitysold.Asaresult,revenuefallsfrom$300to$220.,AnIncreaseinSupplyintheMarketforWheat,$3,QuantityofWheat,100,0,PriceofWheat,1.Whendemandisinelastic,anincreaseinsupply.,Demand,S1,S2,2,110,2.leadstoalargefallinprice.,3.以及销售量的小幅度增加。结果收益从300美元减少为220美元。,小麦市场上供给增加,$3,小麦数量,100,0,小麦价格,当需求缺乏弹性时，供给增加.,需求,S1,S2,2,110,2.引起价格的大幅度下降.,ComputethePriceElasticityofSupply计算供给价格弹性,Demandisinelastic需求缺乏弹性,5,6,$7,4,1,2,3,Quantity数量,12,2,4,6,8,10,14,0,Price价格,Elasticityislargerthan1.弹性大于1,Elasticityis,Smallerthan1.弹性小于1,Figure5-5,$15,12,3,Quantity数量,100,200,500,0,Price价格,525,Elasticityissmall,(lessthan1).,Elasticityislarge,(greaterthan1).,4,Figure5-7,弹性小（1）,P2,P1,QuantityofOil,0,PriceofOil,Demand,S,2,S,1,(a)TheOilMarketintheShortRun,P2,P1,QuantityofOil,0,PriceofOil,Demand,S,2,S,1,(b)TheOilMarketintheLongRun,2.leads,toalarge,increase,inprice.,1.Inthelongrun,whensupplyand,demandareelastic,ashiftinsupply.,2.leadstoasmallincreaseinprice.,1.Intheshortrun,whensupply,anddemandareinelastic,ashiftinsupply.,Figure5-9,P2,P1,石油数量,0,石油价格,需求,S,2,S,1,(a)短期石油市场,P2,P1,石油数量,0,石油价格,需求,S,2,S,1,(b)长期石油市场,2.引起价格大幅度上升,在长期中，当供给与需求富有弹性时，供给移动,2.引起价格小幅度上升,在短期中，当供给和需求缺乏弹性时，供给移动,Figure5-9,P,2,P,1,QuantityofDrugs,0,Q,2,Q,1,Priceof,Drugs,Demand,S,2,S,1,Q,2,Q,1,(a)DrugInterdiction,QuantityofDrugs,0,Priceof,Drugs,Supply,D,2,D,1,(b)DrugEducation,3.andreducesthe,quantitysold.,2.which,raisesthe,price.,2.which,reduces,theprice.,P,1,P,2,1.Druginterdictionreduces,thesupplyofdrugs.,1.Drugeducationreduces,thedemandfordrugs.,3.andreducesthe,quantitysold.,Figure5-10,P,2,P,1,毒品数量,0,Q,2,Q,1,毒品价格,需求,S,2,S,1,Q,2,Q,1,(a)禁毒,毒品数量,0,毒品价格,供给,D,2,D,1,(b)禁毒教育,3.以及减少了销售量。,2.提高了价格,2.降低了价格,P,1,P,2,1.禁毒减少了毒品供给,1.禁毒教育减少了毒品需求,3.以及减少了销售量。,Figure5-10,Summary,Priceelasticityofdemandmeasureshowmuchthequantitydemandedrespondstochangesintheprice.Priceelasticityofdemandiscalculatedasthep