曼昆 经济学原理 配套英文PPTChap_32_MonetaryFiscal.ppt 25页

TheInfluenceofMonetaryandFiscalPolicyonAggregateDemandChapter32Copyright©2001byHarcourt,Inc.Allrightsreserved.  Requestsforpermissiontomakecopiesofanypartoftheworkshouldbemailedto:PermissionsDepartment,HarcourtCollegePublishers,6277SeaHarborDrive,Orlando,Florida32887-6777. AggregateDemandManyfactorsinfluenceaggregatedemandbesidesmonetaryandfiscalpolicy.Inparticular,desiredspendingbyhouseholdsandbusinessfirmsdeterminestheoveralldemandforgoodsandservices.Whendesiredspendingchanges,ADshifts.MonetaryandFiscalpolicyareusedtooffsetthoseshiftsinAD. HowMonetaryPolicyInfluencesAggregateDemandFortheU.S.economy,themostimportantreasonforthedownwardslopeoftheaggregate-demandcurveistheinterest-rateeffect. TheTheoryofLiquidityPreferenceKeynesdevelopedthetheoryofliquiditypreferenceinordertoexplainwhatfactorsdeterminetheeconomy’sinterestrate.Accordingtothetheory,theinterestrateadjuststobalancethesupplyanddemandformoney. MoneySupplyThemoneysupplyiscontrolledbytheFedthrough:Open-marketoperationsChangingthereserverequirementsChangingthediscountrateThusthequantityofmoneysupplieddoesnotdependontheinterestrateandisvertical. MoneyDemandMoneydemandisdeterminedbyseveralfactors.Accordingtothetheoryofliquiditypreference,oneofthemostimportantfactorsistheinterestrate.Peoplechoosetoholdmoneybecausemoneycanbeusedtobuyothergoodsandservices. MoneyDemandTheopportunitycostofholdingmoneyistheinterestthatcouldbeearnedoninterest-earningassets.Anincreaseintheinterestrateraisestheopportunitycostofholdingmoney.Asaresult,thequantityofmoneydemandedisreduced. EquilibriumintheMoneyMarketAccordingtothetheoryofliquiditypreference:Theinterestrateadjuststobalancethesupplyanddemandformoney.Thereisoneinterestrate,calledtheequilibriuminterestrate,atwhichthequantityofmoneydemandedequalsthequantityofmoneysupplied.Thepricelevelisstuckatsomelevel. EquilibriumintheMoneyMarket...QuantityofMoneyInterestRate0MoneydemandQuantityfixedbytheFedMoneysupplyr2Md2r1Md1EquilibriuminterestrateHarcourt,Inc.itemsandderiveditemscopyright©2001byHarcourt,Inc. ChangesintheMoneySupplyTheFedcanshifttheaggregatedemandcurvewhenitchangesmonetarypolicy.Anincreaseinthemoneysupplyshiftsthemoneysupplycurvetotheright.Withoutachangeinthemoneydemandcurve,theinterestratefalls.Fallinginterestratesincreasethequantityofgoodsandservicesdemanded. Y2AD23.…whichincreasesthequantityofgoodsandservicesdemandedatagivenpricelevel.1.WhentheFedincreasesthemoneysupply…MS2AMonetaryInjection...Y1PQuantityofOutput0PriceLevelAggregatedemand,AD1(a)TheMoneyMarketQuantityofMoney0Moneysupply,MS1r1InterestRate(b)TheAggregate-DemandCurver22.…theequilibriuminterestratefalls…Harcourt,Inc.itemsandderiveditemscopyright©2001byHarcourt,Inc. ChangesintheMoneySupplyWhentheFedincreasesthemoneysupply,itlowerstheinterestrateandincreasesthequantityofgoodsandservicesdemandedatanygivenpricelevel,shiftingaggregate-demandtotheright.WhentheFedcontractsthemoneysupply,itraisestheinterestrateandreducesthequantityofgoodsandservicesdemandedatanygivenpricelevel,shiftingaggregate-demandtotheleft. HowFiscalPolicyInfluencesAggregateDemandFiscalpolicyreferstothegovernment’schoicesregardingtheoveralllevelofgovernmentpurchasesortaxes.Fiscalpolicyinfluencessaving,investment,andgrowthinthelongrun.Intheshortrun,fiscalpolicyprimarilyaffectstheaggregatedemand.Fiscalpolicycanbeusedtoaltergovernmentpurchasesortochangetaxes. ChangesinGovernmentPurchasesTherearetwomacroeconomiceffectsfromthechangeingovernmentpurchases:ThemultipliereffectThecrowding-outeffect TheMultiplierEffectGovernmentpurchasesaresaidtohaveamultipliereffectonaggregatedemand.Eachdollarspentbythegovernmentcanraisetheaggregatedemandforgoodsandservicesbymorethanadollar. TheMultiplierEffect...Aggregatedemand,AD1QuantityofOutput0PriceLevelAD21.Anincreaseingovernmentpurchasesof$20billioninitiallyincreasesaggregatedemandby$20billion…$20billionAD32.…butthemultipliereffectcanamplifytheshiftinaggregatedemand. AFormulafortheSpendingMultiplierTheformulaforthemultiplieris:Multiplier=1/(1-MPC)Animportantnumberinthisformulaisthemarginalpropensitytoconsume(MPC).Itisthefractionofextraincomethatahouseholdconsumesratherthansaves. AFormulafortheSpendingMultiplierIftheMPCis3/4,thenthemultiplierwillbe:Multiplier=1/(1-3/4)=4Inthiscase,a$20billionincreaseingovernmentspendinggenerates$80billionofincreaseddemandforgoodsandservices. TheCrowding-OutEffectFiscalpolicymaynotaffecttheeconomyasstronglyaspredictedbythemultiplier.Anincreaseingovernmentpurchasescausestheinterestratetorise.Ahigherinterestratereducesinvestmentspending. TheCrowding-OutEffectWhenthegovernmentincreasesitspurchasesby$20billion,theaggregatedemandforgoodsandservicescouldrisebymoreorlessthan$20billion,dependingonwhetherthemultipliereffectorthecrowding-outeffectislarger. ChangesinTaxesWhenthegovernmentcutspersonalincometaxes,itincreaseshouseholds’take-homepay.Householdssavesomeofthisadditionalincome.Householdsalsospendsomeofitonconsumergoods.Increasedhouseholdspendingshiftstheaggregate-demandcurvetotheright. UsingPolicytoStabilizetheEconomyEconomicstabilizationhasbeenanexplicitgoalofU.S.policysincetheEmploymentActof1946. TheCaseforActiveStabilizationPolicyTheEmploymentActhastwoimplications:Thegovernmentshouldavoidbeingthecauseofeconomicfluctuations.Thegovernmentshouldrespondtochangesintheprivateeconomyinordertostabilizeaggregatedemand. TheCaseAgainstActiveStabilizationPolicySomeeconomistsarguethatmonetaryandfiscalpolicydestabilizestheeconomy.Monetaryandfiscalpolicyaffecttheeconomywithasubstantiallag.Theysuggesttheeconomyshouldbelefttodealwiththeshort-runfluctuationsonitsown. AutomaticStabilizersAutomaticstabilizersarechangesinfiscalpolicythatstimulateaggregatedemandwhentheeconomygoesintoarecessionwithoutpolicymakershavingtotakeanydeliberateaction.Automaticstabilizersincludethetaxsystemandsomeformsofgovernmentspending.