经济学原理第5章.ppt

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1、ElasticityanditsApplicationEconomicsPRINCIPLESOFN.GregoryMankiwPremiumPowerPointSlidesbyRonCronovich5Inthischapter,lookfortheanswerstothesequestions:Whatiselasticity?Whatkindsofissuescanelasticityhelpusunderstand?Whatisthepriceelasticityofdemand?Howisitrelatedtothedemandcurve?Howisitrelatedtor

2、evenue&expenditure?Whatisthepriceelasticityofsupply?Howisitrelatedtothesupplycurve?Whataretheincomeandcross-priceelasticitiesofdemand?1Youdesignwebsitesforlocalbusinesses.Youcharge$200perwebsite,andcurrentlysell12websitespermonth.Yourcostsarerising(includingtheopportunitycostofyourtime),soyou

3、considerraisingthepriceto$250.Thelawofdemandsaysthatyouwon’tsellasmanywebsitesifyouraiseyourprice.Howmanyfewerwebsites?Howmuchwillyourrevenuefall,ormightitincrease?Ascenario…02ELASTICITYANDITSAPPLICATION3ElasticityBasicidea:Elasticitymeasureshowmuchonevariablerespondstochangesinanothervariable.O

4、netypeofelasticitymeasureshowmuchdemandforyourwebsiteswillfallifyouraiseyourprice.Definition:ElasticityisanumericalmeasureoftheresponsivenessofQdorQstooneofitsdeterminants.0ELASTICITYANDITSAPPLICATION4PriceElasticityofDemandPriceelasticityofdemandmeasureshowmuchQdrespondstoachangeinP.Priceelastici

5、tyofdemand=PercentagechangeinQdPercentagechangeinPLooselyspeaking,itmeasurestheprice-sensitivityofbuyers’demand.0ELASTICITYANDITSAPPLICATION5PriceElasticityofDemandPriceelasticityofdemandequals0PQDQ2P2P1Q1Prisesby10%Qfallsby15%15%10%=1.5Priceelasticityofdemand=PercentagechangeinQdPercentagechange

6、inPExample:ELASTICITYANDITSAPPLICATION6PriceElasticityofDemandAlongaDcurve,PandQmoveinoppositedirections,whichwouldmakepriceelasticitynegative.Wewilldroptheminussignandreportallpriceelasticitiesaspositivenumbers.0PQDQ2P2P1Q1Priceelasticityofdemand=PercentagechangeinQdPercentagechangeinPELASTICITY

7、ANDITSAPPLICATION7CalculatingPercentageChanges0PQD$2508B$20012ADemandforyourwebsitesStandardmethodofcomputingthepercentage(%)change:endvalue–startvaluestartvaluex100%GoingfromAtoB,the%changeinPequals($250–$200)