管理经济学-托马斯版Chap006课件

管理经济学-托马斯版pptChap006ElasticityResponsiveness

E

ElasticUnitaryElasticInelasticTable6.1PriceElasticityofDemand(E)

E>1

E=1

E<1Percentagechangeinquantitydemanded

canbepredictedforagivenpercentagechangeinpriceas:%

Qd=%

P

x

EPercentagechangeinpricerequiredforagivenchangeinquantitydemandedcanbepredictedas:%

P=%

Qd

÷

EPriceElasticityofDemand(E)PriceElasticity&TotalRevenueElasticQuantity-effectdominatesUnitaryelasticNodominanteffectInelasticPrice-effectdominatesPricerisesPricefallsTRfallsTRrisesNochangeinTR

NochangeinTR

TRrisesTRfallsTable6.2FactorsAffectingPriceElasticityofDemandAvailabilityofsubstitutesThebetter&morenumerousthesubstitutesforagood,themoreelasticisdemandPercentageofconsumer’sbudgetThegreaterthepercentageoftheconsumer’sbudgetspentonthegood,themoreelasticisdemandTimeperiodofadjustmentThelongerthetimeperiodconsumershavetoadjusttopricechanges,themoreelasticisdemandCalculatingPriceElasticityofDemandPriceelasticitycanbecalculatedbymultiplyingtheslopeofdemand(Q/P)timestheratioofpricetoquantity(P/Q)Priceelasticitycanbemeasuredataninterval(orarc)alongdemand,orataspecificpointonthedemandcurveIfthepricechangeisrelativelysmall,apointcalculationissuitableIfthepricechangespansasizablearcalongthedemandcurve,theintervalcalculationprovidesabettermeasureCalculatingPriceElasticityofDemandComputationofElasticityOveranIntervalWhencalculatingpriceelasticityofdemandoveranintervalofdemand,usetheintervalorarcelasticityformulaComputationofElasticityataPointWhencalculatingpriceelasticityatapointondemand,multiplytheslopeofdemand(Q/P),computedatthepointofmeasure,timestheratioP/Q,usingthevaluesofPandQatthepointofmeasureMethodofmeasuringpointelasticitydependsonwhetherdemandislinearorcurvilinearPointElasticityWhenDemandisLinear

GivenQ=a+bP+cM+dPR,letincome&priceoftherelatedgoodtakespecificvaluesMandPR,respectively

ThenexpressdemandasQ=a′+bP,

wherea′=a+cM+dPRandtheslopeparameterisb=∆Q∕∆PComputeelasticityusingeitherofthetwoformulasbelowwhichgivethesamevalueforEPointElasticityWhenDemandisLinearWhere

P

and

Q

arevaluesofpriceandquantitydemandedatthepointofmeasurealongdemand,andA(=–a′∕b)istheprice-interceptofdemandComputeelasticityusingeitheroftwoequivalentformulasbelowPointElasticityWhenDemandisCurvilinearWhere

∆Q∕∆P

istheslopeofthecurveddemandatthepointofmeasure,PandQarevaluesofpriceandquantitydemandedatthepointofmeasure,andAistheprice-interceptofthetangentlineextendedtocrossthepriceaxisElasticity(Generally)VariesAlongaDemandCurveForlineardemand,priceand

E

varydirectlyThehighertheprice,themoreelasticisdemandThelowertheprice,thelesselasticisdemandForcurvilineardemand,nogeneralruleabouttherelationbetweenpriceandquantitySpecialcaseofQ=aPb

whichhasaconstantpriceelasticity(equaltob)forallpricesConstantElasticityofDemand(Figure6.3)MarginalRevenueMarginalrevenue(MR)isthechangeintotalrevenueperunitchangeinoutputSinceMRmeasurestherateofchangeintotalrevenueasquantitychanges,MRistheslopeofthetotalrevenue(TR)curveUnitsales(Q)PriceTR=P

Q

MR=TR/Q0$4.5014.0023.5033.1042.8052.4062.0071.50Demand&MarginalRevenue(Table6.3)$0

$4.00

$7.00

$9.30

$11.20

$12.00

$12.00

$10.50

--$4.00

$3.00

$2.30

$1.90

$0.80

$0

$-1.50

Demand,MR,&TR

(Figure6.4)PanelAPanelBDemand&MarginalRevenueWheninversedemandislinear,P=A+BQ(A>0,B<0)Marginalrevenueisalsolinear,intersectsthevertical(price)axisatthesamepointasdemand,&istwiceassteepasdemand

MR=A+2BQLinearDemand,MR,&Elasticity(Figure6.5)MR,TR,&PriceElasticity(Table6.4)MarginalrevenueTotalrevenuePriceelasticityofdemandMR>0MR=0MR<0Elastic(│E│>1)TR

decreasesasQ

increases

(P

decreases)TR

ismaximizedTRincreasesasQincreases(Pdecreases)UnitElastic(│E│=1)Inelastic(│E│<1)MarginalRevenue&PriceElasticityForalldemand&marginalrevenuecurves,therelationbetweenmarginalrevenue,price,&elasticitycanbeexpressedasIncomeElasticityIncomeelasticity(EM)measurestheresponsivenessofquantitydemandedtochangesinincome,holdingthepriceofthegood&allotherdemanddeterminantsconstantPositiveforanormalgoodNegativeforaninferiorgoodCross-PriceElasticityCross-priceelasticity(EXR)measurestheresponsivenessofquantitydemandedofgoodXtochangesinthepriceofrelatedgoodR,holdingthepriceofgoodX&allotherdemanddeterminantsforgoodXconstantPositivewhenthetwogoodsaresubstitutesNegativewhenthetwogoodsarecomplementsIntervalElasticityMeasuresTocalcu