北大经院：Chapter33总供给与总需求20160515课件

1第三十三章总需求与总供给AggregateDemandandAggregateSupply1第三十三章总需求与总供给2ButThis“LongRun”isamisleadingguidetocurrentaffaires.“Inthelongrun”wearealldead.Economistssetthemselvestooeasy,toouselessataskifintempestuousseasonstheycanonlytellusthatwhenthestormislongpasttheoceanisflatagain.

__JohnMaynardKeynes2ButThis“LongRun”isamislLongrunandshortrunLong-runmodelpotentialoutput,long-runinflationShort-runmodelcurrentoutput,currentinflationActualoutput=long-runtrend+short-runfluctuationTheshortrunisdefinedtobethelengthoftimeoverwhichthesedeviationsoccur.3LongrunandshortrunLong-run

总需求与总供给

AggregateDemandandAggregateSupply

threekeyfactsaboutshort-runeconomicfluctuations.

howtheeconomyintheshortrundiffersfromtheeconomyinthelongrun.

howtousethemodelofaggregatedemandandaggregatesupplytoexplaineconomicfluctuations.

howshiftsineitheraggregatedemandoraggregatesupplycancauseboomsandrecessions.4

总需求与总供给

AggregateDemandand5短期经济波动

Short-RunEconomicFluctuations经济活动年复一年地波动Economicactivityfluctuatesfromyeartoyear.在大多数年份里，物品与服务的生产是上升的Inmostyearsproductionofgoodsandservicesrises.在过去50年，平均来说，美国经济的生产每年增长约3个百分点。Onaverageoverthepast50years,productionintheU.S.economyhasgrownbyabout3percentperyear.在一些年份，正常的增长没能出现，导致了衰退。Insomeyearsnormalgrowthdoesnotoccur,causingarecession.

5短期经济波动

Short-RunEconomicFlu6短期经济波动

Short-RunEconomicFluctuations衰退是实际GDP下降、收入减少、失业上升的时期ArecessionisaperiodofdecliningrealGDP,fallingincomes,andrisingunemployment.萧条是严重的衰退Adepressionisasevererecession.6短期经济波动

Short-RunEconomicFlu7衰退RecessionsRealGDP

实际GDP:Figure31-1Billionsof1992Dollars19651970197519801985199019952,5003,0003,5004,0004,5005,0005,5006,0006,500$7,000RealGDP短期经济波动一瞥ALookAtShort-RunEconomicFluctuations7衰退RecessionsRealGDPBillions8Recessions(b)InvestmentSpending投资支出Billionsof1992Dollars3004005006007008009001,000$1,100Investmentspending1965197019751980198519901995短期经济波动一瞥ALookAtShort-RunEconomicFluctuations8Recessions(b)InvestmentSpen9Recessions(c)UnemploymentRate失业率Unemploymentrate0246810121965197019751980198519901995PercentofLaborForce短期经济波动一瞥ALookAtShort-RunEconomicFluctuations9Recessions(c)UnemploymentRa10衰退短期经济波动一瞥：中国ALookAtShort-RunEconomicFluctuations:China

实际GDP资料来源：《中国国内生产总值核算历史资料，1952－1995》，《中国统计年鉴》以及作者计算。10衰退短期经济波动一瞥：中国11衰退短期经济波动一瞥：中国ALookAtShort-RunEconomicFluctuations:China(b)投资支出11衰退短期经济波动一瞥：中国12中国：GDP、工业生产总值、固定资产投资年增长率的波动12中国：GDP、工业生产总值、固定资产投资年增长率的波动13关于经济波动的三个关键事实ThreeKeyFactsAboutEconomicFluctuations经济波动是不规则和不可预测的。Economicfluctuationsareirregularandunpredictable.经济当中的波动常常被称作经济周期（或译商业周期）

Fluctuationsintheeconomyareoftencalledthebusinesscycle.Trashindicator(TheChicagoTribune)13关于经济波动的三个关键事实ThreeKeyFacts14关于经济波动的三个关键事实ThreeKeyFactsAboutEconomicFluctuations大多数宏观经济变量一起波动。Mostmacroeconomicvariablesfluctuatetogether.大多数衡量某种收入或生产的宏观经济变量几乎同时波动。Mostmacroeconomicvariablesthatmeasuresometypeofincomeorproductionfluctuatecloselytogether.虽然许多宏观经济变量一起波动，他们波动的幅度并不同。Althoughmanymacroeconomicvariablesfluctuatetogether,theyfluctuatebydifferentamounts.14关于经济波动的三个关键事实ThreeKeyFacts15关于经济波动的三个关键事实ThreeKeyFactsAboutEconomicFluctuations随着产出下降，失业上升。Asoutputfalls,unemploymentrises.实际GDP的变化和失业率的变化呈反向关系。ChangesinrealGDPareinverselyrelatedtochangesintheunemploymentrate.在衰退时期，失业大幅上升。Duringtimesofrecession,unemploymentrisessubstantially.15关于经济波动的三个关键事实ThreeKeyFacts16短期与长期有何不同

HowtheShortRunDiffersFromtheLongRun大多数经济学家相信，古典理论描述了长期而不是短期中的世界。Mosteconomistsbelievethatclassicaltheorydescribestheworldinthelongrunbutnotintheshortrun.货币供给的变化影响长期中的名义变量而非实际变量Changesinthemoneysupplyaffectnominalvariablesbutnotrealvariablesinthelongrun.货币中性（二分法）的假设在研究经济的逐年变化时是不恰当的Theassumptionofmonetaryneutralityisnotappropriatewhenstudyingyear-to-yearchangesintheeconomy.16短期与长期有何不同

HowtheShortRun17经济波动的基本模型

TheBasicModelofEconomicFluctuations我们用两个变量来建立一个模型，以分析短期波动。Twovariablesareusedtodevelopamodeltoanalyzetheshort-runfluctuations.以实际GDP衡量的经济当中物品与服务的产出。Theeconomy’soutputofgoodsandservicesmeasuredbyrealGDP.以CPI或GDP平减指数衡量的整体价格水平。TheoverallpricelevelmeasuredbytheCPIortheGDPdeflator.17经济波动的基本模型

TheBasicModelof18经济波动的基本模型

TheBasicModelofEconomicFluctuations经济学家使用总需求与总供给模型来解释经济活动围绕其长期趋势的短期波动Economistusethemodelofaggregatedemandandaggregatesupplytoexplainshort-runfluctuationsineconomicactivityarounditslong-runtrend.18经济波动的基本模型

TheBasicModelof19经济波动的基本模型

TheBasicModelofEconomicFluctuations总需求曲线表示家庭、企业或政府在任一价格水平上想要购买的物品与服务的数量。 Theaggregatedemandcurve

showsthequantityofgoodsandservicesthathouseholds,firms,andthegovernmentwanttobuyateachpricelevel.19经济波动的基本模型

TheBasicModelof20经济波动的基本模型

TheBasicModelofEconomicFluctuations总供给曲线表示企业在任一价格水平上生产和销售的物品与服务的数量。Theaggregatesupplycurveshowsthequantityofgoodsandservicesthatfirmsproduceandsellateachpricelevel.20经济波动的基本模型

TheBasicModelof21总需求与总供给……

AggregateDemandandAggregateSupply...EquilibriumOutput均衡产出QuantityofOutput产出数量PriceLevel价格水平0Equilibriumpricelevel均衡价格水平AggregateSupply总供给AggregateDemand总需求21总需求与总供给……

AggregateDemanda22总需求曲线

TheAggregateDemandCurveGDP（Y）的四个组成部分构成了对物品与服务的总需求。ThefourcomponentsofGDP(Y)contributetotheaggregatedemandforgoodsandservices.Y=C+I+G+NX22总需求曲线

TheAggregateDemandC23总需求曲线

TheAggregate-DemandCurve...QuantityofOutputPriceLevel0AggregatedemandP1Y1Y2P22.…增加了物品与服务的需求数量increasesthequantityofgoodsandservicesdemanded.1.价格水平的下降Adecreaseinthepricelevel...23总需求曲线

TheAggregate-DemandC24为什么总需求曲线向下倾斜

WhytheAggregateDemandCurveIsDownwardSloping价格水平与消费：财富效应ThePriceLevelandConsumption:TheWealthEffect价格水平与投资：利率效应ThePriceLevelandInvestment:TheInterestRateEffect价格水平与净出口：汇率效应ThePriceLevelandNetExports:TheExchange-RateEffect24为什么总需求曲线向下倾斜

WhytheAggrega25价格水平与消费：财富效应

ThePriceLevelandConsumption:TheWealthEffect价格水平的下降使得消费者感觉更加富有，这反过来鼓励他们支出更多。Adecreaseinthepricelevelmakesconsumersfeelmorewealthy,whichinturnencouragesthemtospendmore.消费支出的上升意味着对物品与服务更大的需求数量。Thisincreaseinconsumerspendingmeanslargerquantitiesofgoodsandservicesdemanded.25价格水平与消费：财富效应

ThePriceLevel26价格水平与投资：利率效应

ThePriceLevelandInvestment:TheInterestRateEffect更低的价格水平增加了储蓄，降低了利率，这鼓励了对投资品的更大支出。Alowerpricelevelreducestheinterestrate,whichencouragesgreaterspendingoninvestmentgoods.投资支出的增加意味着物品与服务的需求数量更大。Thisincreaseininvestmentspendingmeansalargerquantityofgoodsandservicesdemanded.26价格水平与投资：利率效应

ThePriceLevel27价格水平与净出口：汇率效应

ThePriceLevelandnetExports:TheExchange-RateEffect当美国的价格水平下降导致了美国的利率下降，实际汇率就会贬值，这又刺激了美国的净出口。WhenafallintheU.S.pricelevelcausesU.S.interestratestofall,therealexchangeratedepreciates,whichstimulatesU.S.netexports.净出口支出的增加意味着物品与服务的需求数量更大。Theincreaseinnetexportspendingmeansalargerquantityofgoodsandservicesdemanded.27价格水平与净出口：汇率效应

ThePriceLeve28总需求曲线为什么会移动

WhytheAggregateDemandCurveMightShift总需求曲线向下倾斜，表示价格水平的下降增加了物品与服务总的需求数量。Thedownwardslopeoftheaggregatedemandcurveshowsthatafallinthepricelevelraisestheoverallquantityofgoodsandservicesdemanded.然而，在给定价格水平上，许多其他因素影响物品与服务的需求数量。Manyotherfactors,however,affectthequantityofgoodsandservicesdemandedatanygivenpricelevel.当这些其他因素中的任一种发生改变，总需求曲线移动。Whenoneoftheseotherfactorschanges,theaggregatedemandcurveshifts.28总需求曲线为什么会移动

WhytheAggregat29总需求曲线为什么会移动

WhytheAggregateDemandCurveMightShift来自消费的移动ShiftsarisingfromConsumption来自投资的移动ShiftsarisingfromInvestment来自政府购买的移动ShiftsarisingfromGovernmentPurchases来自净出口的移动ShiftsarisingfromNetExports29总需求曲线为什么会移动

WhytheAggregat30总需求曲线的移动

ShiftsintheAggregateDemandCurve...QuantityofOutputPriceLevel0Aggregatedemand,D1P1Y1D2Y230总需求曲线的移动

ShiftsintheAggre31总供给曲线

TheAggregateSupplyCurve在长期中，总供给曲线是垂直的。Inthelongrun,theaggregate-supplycurveisvertical.在短期内，总供给曲线向上倾斜。Intheshortrun,theaggregate-supplycurveisupwardsloping.31总供给曲线

TheAggregateSupplyC32长期总供给曲线

TheLong-RunAggregateSupplyCurve在长期中，经济的物品与服务的生产依赖于它的劳动、资本与自然资源的供给，以及将这些生产要素转化为产品与服务的可行技术。Inthelong-run,aneconomy’sproductionofgoodsandservicesdependsonitssuppliesoflabor,capital,andnaturalresourcesandontheavailabletechnologyusedtoturnthesefactorsofproductionintogoodsandservices.价格水平在长期中不影响这些变量。Thepriceleveldoesnotaffectthesevariablesinthelongrun.32长期总供给曲线

TheLong-RunAggrega33长期总供给曲线

TheLong-RunAggregate-SupplyCurve...QuantityofOutputNaturalrateofoutputPriceLevel0Long-runaggregatesupplyP1P22.…不影响长期中物品与服务的供给数量doesnotaffectthequantityofgoodsandservicessuppliedinthelongrun.1.价格水平的改变Achangeinthepricelevel…33长期总供给曲线

TheLong-RunAggrega34长期总供给曲线

TheLong-RunAggregateSupplyCurve长期总供给曲线垂直于自然产出率处。Thelong-runaggregatesupplycurveisverticalatthenaturalrateofoutput.这一生产水平也被称为潜在产出或充分就业产出。

Thislevelofproductionisalsoreferredtoaspotentialoutputorfull-employmentoutput.34长期总供给曲线

TheLong-RunAggrega35长期总供给曲线为什么会移动WhytheLong-RunAggregateSupplyCurveMightShift任何改变自然产出率的经济变化都会移动长期总供给曲线。Anychangeintheeconomythataltersthenaturalrateofoutputshiftsthelong-runaggregate-supplycurve.这样的移动可以按照古典模型中影响产出的若干因素来分类。Theshiftsmaybecategorizedaccordingtothevariousfactorsintheclassicalmodelthataffectoutput.35长期总供给曲线为什么会移动WhytheLong-Ru36长期总供给曲线为什么移动

WhytheLong-RunAggregateSupplyCurveMightShift来自劳动的移动ShiftsarisingfromLabor来自资本的移动ShiftsarisingfromCapital来自自然资源的移动ShiftsarisingfromNaturalResources来自技术知识的移动ShiftsarisingfromTechnologicalKnowledge36长期总供给曲线为什么移动

WhytheLong-Ru371.在长期中，技术进步移动长期总供给Inthelong-run,technologicalprogressshiftslong-runaggregatesupply...LRAS2000LRAS1990长期增长与通货膨胀……Long-RunGrowthandInflation...QuantityofOutputPriceLevel0P1980Y1980AD1980P2000P1990LRAS19802.…货币供给的增长移动总需求andgrowthinthemoneysupplyshiftsaggregate-demand...AD2000AD19904.…和持续的通货膨胀andongoinginflation.Y1990Y20003.…导致产出增长leadingtogrowthinoutput...371.在长期中，技术进步移动长期总供给38长期增长与通货膨胀

Long-RunGrowthandInflation短期的产出与价格波动应该被看成是对持续的长期趋势的偏离。Short-runfluctuationsinoutputandpricelevelshouldbeviewedasdeviationsfromthecontinuinglong-runtrends.38长期增长与通货膨胀

Long-RunGrowthan39短期总供给曲线为什么向上倾斜

WhytheShort-RunAggregate

SupplyCurveSlopesUpwardintheShortRun在短期内，经济中整体价格水平的上升倾向于增加物品与服务的供给数量。Intheshortrun,anincreaseintheoveralllevelofpricesintheeconomytendstoraisethequantityofgoodsandservicessupplied.价格水平的下降倾向于减少物品与服务的供给数量。Adecreaseinthelevelofpricestendstoreducethequantityofgoodsandservicessupplied.39短期总供给曲线为什么向上倾斜

WhytheShort40短期总供给曲线……

TheShort-RunAggregate

SupplyCurve...QuantityofOutputPriceLevel0Short-runaggregatesupplyY1P1Y22.减少了短期内物品与服务的供给数量reducesthequantityofgoodsandservicessuppliedintheshortrun.P21.价格水平的下降Adecreaseinthepricelevel40短期总供给曲线……

TheShort-RunAggr41短期总供给曲线为什么向上倾斜

WhytheShort-RunAggregate

SupplyCurveSlopesUpwardintheShortRun错觉理论TheMisperceptionsTheory粘性工资理论TheSticky-WageTheory粘性价格理论TheSticky-PriceTheory41短期总供给曲线为什么向上倾斜

WhytheShort42错觉理论

TheMisperceptionsTheory总体价格水平的改变，暂时性地误导供给者，让他们在出售自己产出的市场上，看不清正在发生什么Changesintheoverallpriceleveltemporarilymisleadsuppliersaboutwhatishappeninginthemarketsinwhichtheyselltheiroutput:更低的价格水平导致了对相对价格的错觉。Alowerpricelevelcausesmisperceptionsaboutrelativeprices.这种错觉使得供给者减少物品与服务的供给数量。Thesemisperceptionsinducesupplierstodecreasethequantityofgoodsandservicessupplied.42错觉理论

TheMisperceptionsTheo43粘性工资理论

TheSticky-WageTheory名义工资的调整是缓慢的，或者说，在短期内是“粘性的”。Nominalwagesareslowtoadjust,orare“sticky”intheshortrun:工资并不随着价格水平的下降而立即调整。Wagesdonotadjustimmediatelytoafallinthepricelevel.更低的价格水平使得雇佣和生产的利润更低。Alowerpricelevelmakesemploymentandproductionlessprofitable.这就导致企业减少物品与服务的供给数量。Thisinducesfirmstoreducethequantityofgoodsandservicessupplied.43粘性工资理论

TheSticky-WageTheor44粘性价格理论

TheSticky-PriceTheory某些物品与服务的价格为适应经济状况变化所进行的调整是迟缓的。Pricesofsomegoodsandservicesadjustsluggishlyinresponsetochangingeconomicconditions:价格水平的未预料到的下降，留下某些企业的价格超过了合意的水平。Anunexpectedfallinthepricelevelleavessomefirmswithhigher-than-desiredprices.这会压低销售，引起企业减少物品与服务的生产数量Thisdepressessales,whichinducesfirmstoreducethequantityofgoodsandservicestheyproduce.44粘性价格理论

TheSticky-PriceTheo45短期总供给曲线为什么向上倾斜

WhytheShort-RunAggregate

SupplyCurveSlopesUpwardintheShortRun所有这三个理论都表明，当实际价格水平背离人们预期的（expected）价格水平时，产量就背离其自然率。用数学公式表述如下：

产品供给量＝自然产量率＋a×(实际价格水平－预期价格水平）短期中，预期价格水平难以调整，实际价格水平的上升增加了产品供给量，总供给曲线向上倾斜。长期中，预期价格水平得到调整，以致与实际价格水平相等，总供给曲线垂直于自然产量率处。45短期总供给曲线为什么向上倾斜

WhytheShort46短期总供给曲线为什么向上倾斜

WhytheShort-RunAggregate

SupplyCurveSlopesUpwardintheShortRun在短期内，实际价格下降……而预期价格不变……结果是……错觉理论……供给者自己的产品价格下降……供给者认为其他产品价格不变供给者误认为自己产品的相对价格下降，从而减少产出粘性工资理论……供给者自己的产品价格下降……供给者不能调整名义工资供给者由于产品价格下降而减少产出粘性价格理论……其他供给者的价格下降……供给者自己产品的价格无法调整供给者自己产品的相对价格上升，需求下降，从而减少产出。46短期总供给曲线为什么向上倾斜

WhytheShort47总供给曲线为什么会移动

WhytheAggregateSupplyCurveMightShift来自劳动力的移动ShiftsarisingfromLabor来自资本的移动ShiftsarisingfromCapital来自自然资源的移动ShiftsarisingfromNaturalResources.来自技术的移动ShiftsarisingfromTechnology.来自预期价格水平的移动ShiftsarisingfromtheExpectedPriceLevel.47总供给曲线为什么会移动

WhytheAggregat48预期价格水平的上升减少了物品与服务的供给数量，将短期总供给曲线向左移动。Anincreaseintheexpectedpricelevelreducesthequantityofgoodsandservicessuppliedandshiftstheshort-runaggregatesupplycurvetotheleft.预期价格水平的下降增加了物品与服务的供给数量，将短期总供给曲线向右移动。Adecreaseintheexpectedpricelevelraisesthequantityofgoodsandservicessuppliedandshiftstheshort-runaggregatesupplycurvetotheright.总供给曲线为什么会移动

WhytheAggregateSupplyCurveMightShift48预期价格水平的上升减少了物品与服务的供给数量，将短期总供49长期均衡

TheLong-RunEquilibriumQuantityofOutput产量PriceLevel价格水平0Short-runaggregatesupply短期总供给Long-runaggregatesupply长期总供给总需求AggregateDemandAEquilibrium

price均衡价格Naturalrateofoutput自然产出率49长期均衡

TheLong-RunEquilibriu50总需求移动

ShiftsinAggregateDemand在短期内，总需求的移动导致经济中物品与服务的产出发生波动。Intheshortrun,shiftsinaggregatedemandcausefluctuationsintheeconomy’soutputofgoodsandservices.在长期中，总需求的移动影响整体的价格水平但不影响产出。Inthelongrun,shiftsinaggregatedemandaffecttheoverallpricelevelbutdonotaffectoutput.50总需求移动

ShiftsinAggregateDe1.总需求减少Adecreaseinaggregatedemand…AD2总需求的收缩……

AContractioninAggregateDemand...QuantityofOutputPriceLevel0Short-runaggregatesupply,AS1

Long-runaggregatesupplyAggregatedemand,AD1AP1Y1BP2Y22.…导致产出在短期内下降causesoutputtofallintheshortrun…AS2CP33.…但是随着时间推移，短期总供给曲线移动butovertime,theshort-runaggregate-supplycurveshifts…4.…产出回到其自然率上andoutputreturnstoitsnaturalrate.1.总需求减少AD2总需求的收缩……

AContract52总供给的不利移动

AnAdverseShiftinAggregateSupply总供给的某个决定因素的下降将曲线向左移动。Adecreaseinoneofthedeterminantsofaggregatesupplyshiftsthecurvetotheleft:产出下降到自然率之下。Outputfallsbelowthenaturalrateofemployment.失业增加Unemploymentrises.价格上升Thepricelevelrises.52总供给的不利移动

AnAdverseShiftin531.短期总供给曲线的不利移动Anadverseshiftintheshort-runaggregate-supplycurve…AS2Long-runaggregatesupplyShort-runaggregatesupply,AS1QuantityofOutputPriceLevel0AggregatedemandAY1P1总供给的不利移动……

An

AdverseShiftinAggregateSupply...3.…和价格水平上升andthepriceleveltorise.

P22.…导致产出下降causesoutputtofall…BY2531.短期总供给曲线的不利移动Anadversesh54滞胀

Stagflation总供给的不利移动导致滞胀——衰退和通货膨胀并存。Adverseshiftsinaggregatesupplycausestagflation—acombinationofrecessionandinflation.产出下降，价格上升。Outputfallsandpricesrise.政策制订者能够影响总需求，但不能同时抵消这两种不利的影响。Policymakerswhocaninfluenceaggregatedemandcannotoffsetbothoftheseadverseeffectssimultaneously.54滞胀

Stagflation总供给的不利移动导致滞胀——55对于衰退的政策反应

PolicyResponsestoRecession政策制定者对衰退的反应可以是以下方式之一Policymakersmayrespondtoarecessioninoneofthefollowingways:什么也不做，等待价格和工资的调整。Donothingandwaitforpricesandwagestoadjust.采取行动，通过货币与财政政策来增加总需求。Takeactiontoincreaseaggregatedemandbyusingmonetaryandfiscalpolicy.55对于衰退的政策反应

PolicyResponsest56AS21.当短期总供给减少Whenshort-runaggregatesupplyfalls…适应总供给的不利移动……

AccommodatinganAdverseShiftinAggregateSupply...QuantityofOutputNaturalrateofoutputPriceLevel0Short-runaggregatesupply,AS1

Aggregatedemand,AD1Long-runaggregatesupplyAP1P2P33.…这会引起价格上升whichcausesthepriceleveltorise4.…但是保持产出处于自然率butkeepsoutputatitsnaturalrate.C2.…政策制定者可以通过扩张总需求来适应这一移动policymakerscanaccommodatetheshiftbyexpandingaggregatedemand…AD256AS21.当短期总供给减少适应总供给的不利移动……

A57总供给移动的效应

TheEffectsofaShiftinAggregateSupply总供给的移动可能引起滞胀——衰退与通货膨胀并存。Shiftsinaggregatesupplycancausestagflation–acombinationofrecessionandinflation.政策制定者能够影响总需求，却不能同时抵消这两种不利的影响。Policymakerswhocaninfluenceaggregatedemandcannotoffsetbothoftheseadverseeffectssimultaneously.57总供给移动的效应

TheEffectsofaSh58总结

Summary所有社会都经历了围绕长期趋势的短期经济波动Allsocietiesexperienceshort-runeconomicfluctuationsaroundlong-runtrends.这些波动是不规则的，大多不可预测。Thesefluctuationsareirregularandlargelyunpredictable.当衰退发生时，实际GDP和其他一些衡量收入、支出和生产的指标都会下降，失业上升。Whenrecessionsoccur,realGDPandothermeasuresofincome,spending,andproductionfall,andunemploymentrises.58总结

Summary所有社会都经历了围绕长期趋势的短期经59总结

Summary经济学家使用总需求与总供给模型来分析短期经济波动。Economistsanalyzeshort-runeconomicfluctuationsusingtheaggregatedemandandaggregatesupplymodel.按照总需求与总供给模型，物品与服务的产出和整体价格水平做出调整，以平衡总需求与总供给。Accordingtothemodelofaggregatedemandandaggregatesupply,theoutputofgoodsandservicesandtheoveralllevelofpricesadjusttobalanceaggregatedemandandaggregatesupply.59总结

Summary经济学家使用总需求与总供给模型来分析60总结

Summary总需求曲线向下倾斜的原因有三：财富效应、利率效应与汇率效应。Theaggregate-demandcurveslopesdownwardforthreereasons:awealtheffect,aninterestrateeffect,andanexchangerateeffect.如果任何事件或政策在给定的价格水平上改变了消费、投资、政府购买或净出口，它也将移动总需求曲线。Anyeventorpolicythatchangesconsumption,investment,governmentpurchases,ornetexportsatagivenpricelevelwillshifttheaggregate-demandcurve.60总结

Summary总需求曲线向下倾斜的原因有三：财富效61总结

Summary在长期中，总供给曲线是垂直的。Inthelongrun,theaggregatesupplycurveisvertical.在短期内，总供给曲线向上倾斜。Theshort-run,theaggregatesupplycurveisupwardsloping.解释短期总供给曲线向上倾斜的理论有三个：错觉理论、粘性工资理论与粘性价格理论。Thearethreetheoriesexplainingtheupwardslopeofshort-runaggregatesupply:themisperceptionstheory,thesticky-wagetheory,andthesticky-pricetheory.61总结

Summary在长期中，总供给曲线是垂直的。62总结

Summary改变经济产出能力的事件，将移动短期总供给曲线。Eventsthataltertheeconomy’sabilitytoproduceoutputwillshifttheshort-runaggregate-supplycurve.此外，短期总供给曲线的位置依赖于预期价格水平。Also,thepositionoftheshort-runaggregate-supplycurvedependsontheexpectedpricelevel.经济波动的一个可能成因是总需求的移动。Onepossiblecauseofeconomicfluctuationsisashiftinaggregatedemand.62总结

Summary改变经济产出能力的事件，将移动短期总63总结

Summary经济波动的第二个可能的成因是总供给的移动。Asecondpossiblecauseofeconomicfluctuationsisashiftinaggregatesupply.滞胀是产出下降且价格上升的时期。Stagflationisaperiodoffallingoutputandrisingprices.63总结

Summary经济波动的第二个可能的成因是总供给的64第三十三章总需求与总供给AggregateDemandandAggregateSupply1第三十三章总需求与总供给65ButThis“LongRun”isamisleadingguidetocurrentaffaires.“Inthelongrun”wearealldead.Economistssetthemselvestooeasy,toouselessataskifintempestuousseasonstheycanonlytellusthatwhenthestormislongpasttheoceanisflatagain.

__JohnMaynardKeynes2ButThis“LongRun”isamislLongrunandshortrunLong-runmodelpotentialoutput,long-runinflationShort-runmodelcurrentoutput,currentinflationActualoutput=long-runtrend+short-runfluctuationTheshortrunisdefinedtobethelengthoftimeoverwhichthesedeviationsoccur.66LongrunandshortrunLong-run

总需求与总供给

AggregateDemandandAggregateSupply

threekeyfactsaboutshort-runeconomicfluctuations.

howtheeconomyintheshortrundiffersfromtheeconomyinthelongrun.

howtousethemodelofaggregatedemandandaggregatesupplytoexplaineconomicfluctuations.

howshiftsineitheraggregatedemandoraggregatesupplycancauseboomsandrecessions.67

总需求与总供给

AggregateDemandand68短期经济波动

Short-RunEconomicFluctuations经济活动年复一年地波动Economicactivityfluctuatesfromyeartoyear.在大多数年份里，物品与服务的生产是上升的Inmostyearsproductionofgoodsandservicesrises.在过去50年，平均来说，美国经济的生产每年增长约3个百分点。Onaverageoverthepast50years,productionintheU.S.economyhasgrownbyabout3percentperyear.在一些年份，正常的增长没能出现，导致了衰退。Insomeyearsnormalgrowthdoesnotoccur,causingarecession.

5短期经济波动

Short-RunEconomicFlu69短期经济波动

Short-RunEconomicFluctuations衰退是实际GDP下降、收入减少、失业上升的时期ArecessionisaperiodofdecliningrealGDP,fallingincomes,andrisingunemployment.萧条是严重的衰退Adepressionisasevererecession.6短期经济波动

Short-RunEconomicFlu70衰退RecessionsRealGDP

实际GDP:Figure31-1Billionsof1992Dollars19651970197519801985199019952,5003,0003,5004,0004,5005,0005,5006,0006,500$7,000RealGDP短期经济波动一瞥ALookAtShort-RunEconomicFluctuations7衰退RecessionsRealGDPBillions71Recessions(b)InvestmentSpending投资支出Billionsof1992Dollars3004005006007008009001,000$1,100Investme