货币金融学（第十三版）课件 英文第20章 IS曲线

TheEconomicsofMoney,Banking,andFinancialMarketsThirteenthEditionChapter20TheI

SCurveCopyright©2022,2019,2016PearsonEducation,Inc.AllRightsReservedPreviewThischapterdevelopstheI

Sschedule,whichdescribestherelationshipbetweenrealinterestratesandaggregateoutputwhenthemarketforrealgoodsandservicesisinequilibrium.LearningObjectives20.1Listthefourcomponentsofaggregatedemand(orplannedexpenditure).20.2Listanddescribethefactorsthatdeterminethefourcomponentsofaggregatedemand(orplannedexpenditure).20.3Solveforthegoodsmarketequilibrium.20.4DescribewhytheI

Scurveslopesdownwardandwhytheeconomyheadstoagoodsmarketequilibrium.20.5ListthefactorsthatshifttheI

ScurveanddescribehowtheyshifttheI

Scurve.PlannedExpenditureandAggregateDemand(1of2)Plannedexpenditureisthetotalamountofspendingondomesticallyproducedgoodsandservicesthathouseholds,businesses,thegovernment,andforeignerswanttomake.Aggregatedemandisthetotalamountofoutputdemandedintheeconomy.PlannedExpenditureandAggregateDemand(2of2)Thetotalquantitydemandedofaneconomy’soutputisthesumof4typesofspending:Consumptionexpenditure(C)Plannedinvestmentspending(I)Governmentpurchases(G)Netexports(N

X)TheComponentsofAggregateDemandConsumptionexpenditureandtheconsumptionfunction:IncomeisthemostimportantfactordeterminingconsumptionspendingDisposableincomeistotalincomelesstaxesThemarginalpropensitytoconsume(m

p

c)

istheslopeoftheconsumptionfunctionthechangeinconsumerexpenditurethatresultsfromanadditionaldollarofdisposableincomeaisautomonousconsumerexpenditure,theamountofconsumerexpenditurethatisindependentofdisposableincome(howmuchwillbespentwhendisposableincomeis0)F

Y

I:MeaningoftheWordInvestmentEconomistsusethewordinvestment

somewhatdifferentlythanotherpeopledo.Whennon-economistssaythattheyaremakinganinvestment,theyarenormallyreferringtothepurchaseofcommonstocksorbonds,purchasesthatdonotnecessarilyinvolvenewlyproducedgoodsandservices.Butwheneconomistsspeakofinvestmentspending,theyarereferringtothepurchasesofnew

physicalassets,suchasnewmachinesornewhouses—purchasesthataddtoaggregatedemandPlannedInvestmentSpendingFixedinvestmentarealwaysplanned.Inventoryinvestmentcanbeunplanned.PlannedinvestmentspendingInterestratesExpectationsGovernmentPurchasesandTaxesThegovernmentaffectsaggregatedemandintwoways:throughitspurchasesandtaxes.Governmentpurchasesadddirectlytoaggregatedemand,whiletaxesindirectlyeffectsspendingbychangingdisposable,orafter-taxincome.Governmentpurchases:Governmenttaxes:NetExportsMadeupoftwocomponents:autonomousnetexportsandthepartofnetexportsthatisaffectedbychangesinrealinterestratesNetexportfunction:GoodsMarketEquilibriumKeynesrecognizedthatequilibriumwouldoccurintheeconomywhenthetotalquantityofoutputproducedintheeconomyequalsthetotalamountofaggregatedemand(plannedexpenditure).Solvingforgoodsmarketequilibrium:AggregateOutput=ConsumptionExpenditure+PlannedInvestmentSpending+GovernmentPurchases+NetExportsUnderstandingtheI

SCurveWhattheI

Scurvetellsus:tracesoutthepointsatwhichthegoodsmarketisinequilibriumExaminesanequilibriumwhereaggregateoutputequalsaggregatedemandAssumesfixedpricelevelwherenominalandrealquantitiesarethesameI

Scurveistherelationshipbetweenequilibriumaggregateoutputandtheinterestrate.Figure1TheI

SCurveWhytheEconomyHeadsTowardtheEquilibriumInterestratesandplannedinvestmentspendingNegativerelationshipInterestratesandnetexportsNegativerelationshipI

Scurve:thepointsatwhichthetotalquantityofgoodsproducedequalsthetotalquantityofgoodsdemandedOutputtendstomovetowardpointsonthecurvethatsatisfiesthegoodsmarketequilibrium.FactorsThatShifttheI

SCurve(1of3)TheI

Scurveshiftswheneverthereisachangeinautonomousfactors(factorsindependentofaggregateoutputandtherealinterestrate).Oneexampleischangesingovernmentpurchases,asinFigure2.Figure2ShiftintheI

SCurveFromanIncreaseinGovernmentPurchasesApplication:TheVietnamWarBuildup,1964–1969TheUnitedStates’involvementinVietnambegantoescalateintheearly1960s.Usuallyduringaperiodwhengovernmentpurchasesarerisingrapidly,centralbanksraiserealinterestratestokeeptheeconomyfromoverheating.TheVietnamWarperiod,however,isunusualbecausetheFederalReservedecidedtokeeprealinterestratesconstant.Hence,thisperiodprovidesanexcellentexampleofhowpolicymakerscouldmakeuseoftheI

Scurveanalysistoinformpolicy.Figure3VietnamWarBuildupChangesinTaxesAtanygivenrealinterestrate,ariseintaxescausesaggregatedemandandhenceequilibriumoutputtofall,therebyshiftingtheI

Scurvetotheleft.Conversely,acutintaxesatanygivenrealinterestrateincreasesdisposableincomeandcausesaggregatedemandandequilibriumoutputtorise,shiftingtheI

Scurvetotheright.Figure4ShiftintheI

SCurveFromanIncreaseinTaxesAnotherexampleofwhatshiftstheI

Scurveischangesintaxes,asinFigure4Application:TheFiscalStimulusPackageof2009(1of2)Inthefallof2008,theU.S.economywasincrisis.BythetimethenewObamaadministrationhadtakenoffice,theunemploymentratehadrisenfrom4.7%justbeforetherecessionbeganinDecember2007to7.6%inJanuary2009.Tostimulatetheeconomy,theObamaadministrationproposedafiscalstimuluspackagethat,whenpassedbyCongress,included$288billionintaxcutsforhouseholdsandbusinessesand$499billioninincreasedfederalspending,includingtransferpayments.Application:TheFiscalStimulusPackageof2009(2of2)Thesetaxcutsandspendingincreaseswerepredictedtoincreaseaggregatedemand,therebyraisingtheequilibriumlevelofaggregateoutputatanygivenrealinterestrateandsoshiftingtheI

Scurvetotheright.Unfortunately,mostofthegovernmentpurchasesdidnotkickinuntilafter2010,whilethedeclineinautonomousconsumptionandinvestmentwasmuchlargerthananticipated.Thefiscalstimuluswasmorethanoffsetbyweakconsumptionandinvestment,withtheresultthattheaggregatedemandendedupcontractingratherthanrising,andtheI

Scurvedidnotshifttotheright,ashoped.FactorsThatShifttheI

SCurve(2of3)ChangesinautonomousspendingalsoaffecttheI

Scurve:AutonomousconsumptionAutonomousinvestmentspendingAutonomousnetexportsAutonomousConsumptionAriseinautonomousconsumptionwouldraiseaggregatedemandandequilibriumoutputatanygiveninterestrate,shiftingtheI

Scurvetotheright.Conversely,adeclineinautonomousconsumptionexpenditurecausesaggregatedemandandequilibriumoutputtofall,shiftingtheI

Scurvetotheleft.AutonomousInvestmentSpendingAnincreaseinautonomousinvestmentspendingincreasesequilibriumoutputatanygiveninterestrate,shiftingtheI

Scurvetotheright.Ontheotherhand,adecreaseinautonomousinvestmentspendingcausesaggregatedemandandequilibriumoutputtofall,shiftingtheI

Scurvetotheleft.AutonomousNetExportsAnautonomousincreaseinnetexportsleadstoanincreaseinequilibriumoutputatanygiveninterestrateandshiftstheI

Scurvetotheright.Conversely,anautonomousfallinnetexportscausesaggregatedemandandequilibriumoutputtodecline,shiftingtheI

Scurvetotheleft.FactorsThatShifttheI

SCurve(3of3)AnotherfactorthatshiftstheI

ScurveischangesinfinancialfrictionsAnincreaseinfinancialfrictions,asoccurredd