財(cái)貨市場(chǎng)均衡凱因斯課件

財(cái)貨市場(chǎng)均衡凱因斯課件頭腦體操？為什麼會(huì)有失業(yè)？造成的原因是什麼？1930年代經(jīng)濟(jì)大恐慌，為何有普遍失業(yè)的現(xiàn)象?失業(yè)產(chǎn)生究竟是因?yàn)槠髽I(yè)生產(chǎn)萎縮(供給不足)所致，還是商品賣不出去(需求不足)所致?近一二年，全球及臺(tái)灣普遍高失業(yè)率的現(xiàn)象，是供給面還是需求面所引起？臺(tái)灣經(jīng)濟(jì)不好，是那裡出了問題？中央要「拼經(jīng)濟(jì)，救臺(tái)灣」，如何拼法呢？過去臺(tái)灣經(jīng)濟(jì)不好時(shí)，政府總會(huì)提出振興投資方案、擴(kuò)大內(nèi)需政策---等，建立在什麼觀點(diǎn)上？你認(rèn)為成效又如何？增加一元的投資支出或政府支出，可創(chuàng)造比一元還多的產(chǎn)出或所得，可能嗎？為何？決定家計(jì)消費(fèi)支出的因素為何？決定企業(yè)投資的關(guān)鍵又如何？「節(jié)儉是美德」嗎？一經(jīng)濟(jì)社會(huì)人們想增加儲(chǔ)蓄，是否整個(gè)經(jīng)濟(jì)社會(huì)儲(chǔ)蓄水準(zhǔn)就會(huì)增加？政府財(cái)政政策，如何能達(dá)到經(jīng)濟(jì)穩(wěn)定的目的？利用何種財(cái)政工具？國外經(jīng)濟(jì)不景氣，臺(tái)灣經(jīng)濟(jì)跟著不好，如何說明這種現(xiàn)象？頭腦體操？為什麼會(huì)有失業(yè)？造成的原因是什麼？簡單凱因斯模型--理論基礎(chǔ)依據(jù)：凱因斯1936年「就業(yè)、利息與貨幣的一般理論」，1930年代經(jīng)濟(jì)大恐慌提出。是需要面經(jīng)濟(jì)學(xué)，主要說明失業(yè)為何產(chǎn)生及如何解決失業(yè)問題。當(dāng)時(shí)勞動(dòng)未充分就業(yè)，工資又無法向下調(diào)整，使企業(yè)缺乏增加勞動(dòng)雇用的誘因。解決失業(yè)問題之法在提高總需求，貨暢其流，東西有銷路，生產(chǎn)增加，勞動(dòng)需求自然增加。古典經(jīng)濟(jì)學(xué)：是供給面經(jīng)濟(jì)學(xué)，經(jīng)由自由市場(chǎng)的價(jià)格機(jī)能，經(jīng)濟(jì)常處於充分就業(yè)狀態(tài)，資本、技術(shù)、勞動(dòng)供給量等生產(chǎn)能量決定總供給，總需求只影響物價(jià)水準(zhǔn)而已。模式：依總合供需圖而言凱因斯學(xué)派—AS水平，產(chǎn)出與就業(yè)決定於總需求。古典學(xué)派—AS垂直，產(chǎn)出與就業(yè)決定於總供給，總需求只影響物價(jià)水準(zhǔn)。中間區(qū)—AS正斜率，總需求與總供給共同決定產(chǎn)出、就業(yè)與物價(jià)。假定：物價(jià)不變，不計(jì)利率或金融(貨幣)面的作用(本章)主旨：民間消費(fèi)、企業(yè)投資、政府支出、對(duì)外貿(mào)易如何影響一國所得3簡單凱因斯模型--理論基礎(chǔ)依據(jù)：凱因斯1936年「就業(yè)、利息3-1TheCompositionofGDPTable3-1TheCompositionofU.S.GDP,2006Billionsofdollars

PercentofGDPGDP(Y)13,246100.01Consumption(C)9,26970.02Investment(I)2,16316.3Nonresidential

1,39610.5Residential7675.83Governmentspending(G)2,52819.04Netexports7635.8

Exports(X)1,46611.0

Imports(IM)2,22916.85Inventoryinvestment490Source:SurveyofCurrentBusiness,April2007,Table1-1-5.43-1TheCompositionofGDPTab3-1TheCompositionofGDPConsumption(C)referstothegoodsandservicespurchasedbyconsumers.

Investment(I),sometimescalledfixedinvestment,isthepurchaseofcapitalgoods.Itisthesumofnonresidentialinvestmentandresidentialinvestment.

GovernmentSpending(G)referstothepurchasesofgoodsandservicesbythefederal,state,andlocalgovernments.Itdoesnotincludegovernmenttransfers,norinterestpaymentsonthegovernmentdebt.53-1TheCompositionofGDPCon3-1TheCompositionofGDPImports(IM)arethepurchasesofforeigngoodsandservicesbyconsumers,businessfirms,andtheU.S.government.

Exports(X)arethepurchasesofU.S.goodsandservicesbyforeigners.63-1TheCompositionofGDPImp3-1TheCompositionofGDPInventoryinvestmentisthedifferencebetweenproductionandsales.Netexports(XIM)isthedifferencebetweenexports

andimports,alsocalledthetradebalance.73-1TheCompositionofGDPInv3-2TheDemandforGoodsThetotaldemandforgoodsiswrittenas:Thesymbol“”meansthatthisequationisanidentity,ordefinition.TodetermineZ,somesimplificationsmustbemade:

Assumethatallfirmsproducethesamegood,whichcanthenbeusedbyconsumersforconsumption,byfirmsforinvestment,orbythegovernment.

83-2TheDemandforGoodsThet3-2TheDemandforGoodsAssumethatfirmsarewillingtosupplyanyamountofthegoodatagivenprice,P,anddemandinthatmarket.

Assumethattheeconomyisclosed,thatitdoesnottradewiththerestoftheworld,thenbothexportsandimports

arezero.Undertheassumptionthattheeconomyisclosed,

X=IM=0,then:93-2TheDemandforGoods93-2TheDemandforGoodsDisposableincome,(YD),istheincomethatremainsonceconsumershavepaidtaxesandreceivedtransfersfromthegovernment.ThefunctionC(YD)iscalledtheconsumptionfunction.Itisabehavioralequation,thatis,itcapturesthebehaviorofconsumers.Consumption(C)Amorespecificformoftheconsumptionfunctionisthislinearrelation:103-2TheDemandforGoodsDispo簡單凱因斯模型—民間消費(fèi)與儲(chǔ)蓄影響消費(fèi)支出的因素：可支配所得、利率、未來預(yù)期、資產(chǎn)或財(cái)富多寡、物價(jià)水準(zhǔn)、貸款信用的條件與數(shù)量、所得分配狀況、家庭人口數(shù)與年齡結(jié)構(gòu)。消費(fèi)支出與可支配所得關(guān)係：凱恩斯提出消費(fèi)基本心理法則(fundamentalpsychologicallaw)

所得增加消費(fèi)支出增加；但消費(fèi)額增量小於所得增量；且隨所得增加，平均消費(fèi)額下降。消費(fèi)函數(shù)：C＝co＋c1YD，Co是自發(fā)性消費(fèi)、c1YD是誘發(fā)性消費(fèi)，0＜c1＜1。消費(fèi)傾向：邊際消費(fèi)傾向(MPC)＝ΔC/ΔYD＝c

平均消費(fèi)傾向(APC)＝C/YD＝(co/YD

)＋c1＞MPC儲(chǔ)蓄函數(shù)：S＝Y(jié)D－C＝－co＋(1－c1)YD，

MPS＝ΔS/ΔYD，APS＝S/YD

消費(fèi)傾向與儲(chǔ)蓄傾向關(guān)係：MPC＋MPS＝1，APC＋APS＝111簡單凱因斯模型—民間消費(fèi)與儲(chǔ)蓄影響消費(fèi)支出的因素：可支配所得可支配所得、消費(fèi)、儲(chǔ)蓄

單位：萬元YCS△Y△C△SAPCAPSMPCMPC06-6-------1012-210641.2-20.60.42018210640.90.10.60.43024410640.80.20.60.440301010640.750.250.60.450361410640.720.280.60.460421810640.700.300.60.470482210640.690.310.60.412可支配所得、消費(fèi)、儲(chǔ)蓄3-2TheDemandforGoodsThisfunctionhastwoparameters,c0andc1:

c1iscalledthe(marginal)propensitytoconsume,ortheeffectofanadditionaldollarofdisposableincomeonconsumption.

c0istheinterceptoftheconsumptionfunction. Disposableincomeisgivenby:Consumption(C)133-2TheDemandforGoodsThis3-2TheDemandforGoodsConsumption(C)Consumptionincreaseswithdisposableincomebutlessthanoneforone.ConsumptionandDisposableIncomeFigure3-1143-2TheDemandforGoodsConsu3-2TheDemandforGoodsVariablesthatdependonothervariableswithinthemodelarecalledendogenous.Variablesthatarenotexplainwithinthemodelarecalledexogenous.Investmenthereistakenasgiven,ortreatedasanexogenousvariable:

Investment(I)GovernmentSpending(G)Governmentspending,G,togetherwithtaxes,T,describesfiscalpolicy—thechoiceoftaxesandspendingbythegovernment.153-2TheDemandforGoodsVaria3-2TheDemandforGoods

WeshallassumethatGandTarealsoexogenousfortworeasons:

Governmentsdonotbehavewiththesameregularityasconsumersorfirms.

Macroeconomistsmustthinkabouttheimplicationsofalternativespendingandtaxdecisionsofthegovernment.163-2TheDemandforGoodsWes簡單凱因斯模型—投資支出定義：投資指新資本財(cái)?shù)馁徺I，資本財(cái)含機(jī)械設(shè)備、建築物(合稱固定資本)，及存貨變動(dòng)。投資毛額＝投資淨(jìng)額＋資本折舊，Kt＋1＝Kt＋I(xiàn)t(投資毛額)－Dt＝Kt＋I(xiàn)nt(投資淨(jìng)額)影響投資需求因素：最適投資量決定於投資的邊際收益＝邊際成本成本方面—利率(投資的機(jī)會(huì)成本)下降、資本財(cái)價(jià)格下降，投資需求增加；反之，則減少。收益方面—產(chǎn)品未來銷售量或價(jià)格看好、技術(shù)改良或創(chuàng)新出現(xiàn)、資本設(shè)備利用率高、生產(chǎn)成本降低、稅捐減輕，投資需求增加；反之，則減少。

(政府公共投資有助於改善投資環(huán)境，而降低民間生產(chǎn)成本，提高民間投資意願(yuàn)；但擴(kuò)大支出以發(fā)行大量公債支應(yīng)，可能刺激利率上揚(yáng)，不利民間投資。)投資函數(shù)：I＝I(i，Y)，i是利率，Y是所得17簡單凱因斯模型—投資支出定義：投資指新資本財(cái)?shù)馁徺I，資本財(cái)含3-3TheDeterminationofEquilibriumOutputAssumingthatexportsandimportsarebothzero,thedemandforgoodsisthesumofconsumption,investment,andgovernmentspending:Then:183-3TheDeterminationofEquiEquilibriuminthegoodsmarketrequiresthatproduction,Y,beequaltothedemandforgoods,Z:Then:Theequilibriumconditionisthat,production,Y,beequaltodemand.Demand,Z,inturndependsonincome,Y,whichitselfisequaltoproduction.3-3TheDeterminationofEquilibriumOutput19Equilibriuminthegoodsmarke3-3TheDeterminationofEquilibriumOutputMacroeconomistsalwaysusethesethreetools:AlgebratomakesurethatthelogiciscorrectGraphstobuildtheintuitionWordstoexplaintheresults203-3TheDeterminationofEqui3-3TheDeterminationofEquilibriumOutput

Rewritetheequilibriumequation:

UsingAlgebra

Movetotheleftsideandreorganizetherightside:

Dividebothsidesby213-3TheDeterminationofEquiTheequilibriumequationcanbemanipulatedtoderivesomeimportantterms:

Autonomousspendingandthemultiplier:Thetermisthatpartofthedemandforgoodsthatdoesnotdependonoutput,itiscalledautonomousspending.Ifthegovernmentranabalancedbudget,thenT=G.Becausethepropensitytoconsume(c1)isbetweenzeroandone,isanumbergreaterthanone.Forthisreason,thisnumberiscalledthemultiplier.3-3TheDeterminationofEquilibriumOutputUsingAlgebra22Theequilibriumequationcanb均衡所得決定—封閉經(jīng)濟(jì)假定：不計(jì)國外部門，投資需求、政府支出外生決定，租稅為定額稅。均衡：Z=AE＝Y(jié)，預(yù)擬總支出(C+I+G消費(fèi)支出、投資支出政府支出)與總產(chǎn)出或所得相等；Y＝1/(1－c1)×(co＋I(xiàn)0+G-c1T0)或原先打算進(jìn)行的預(yù)擬(或事前)投資與預(yù)擬儲(chǔ)蓄相等，S＝I。(國民所得帳之C,S,I是事後或?qū)嶋H發(fā)生的數(shù)量，實(shí)現(xiàn)的儲(chǔ)蓄必恆等於實(shí)現(xiàn)的投資)如Z=AE＞Y或I＞S，表非意願(yuàn)存貨減少，企業(yè)增加生產(chǎn)，所得增加，直到Z=AE＝Y(jié)為止。如Z=AE＜Y或I＜S，表非意願(yuàn)存貨增加，企業(yè)減少生產(chǎn)，所得下降，直到Z=AE＝Y(jié)為止。23均衡所得決定—封閉經(jīng)濟(jì)233-3TheDeterminationofEquilibriumOutputFirst,plotproductionasafunctionofincome.Second,plotdemandasafunctionofincome.InEquilibrium,productionequalsdemand.Equilibriumoutputisdeterminedbytheconditionthatproductionbeequaltodemand.EquilibriumintheGoodsMarketFigure3-2UsingaGraph243-3TheDeterminationofEquiUsingaGraphAnincreaseinautonomousspendinghasamorethanone-for-oneeffectonequilibriumoutput.TheEffectsofanIncreaseinAutonomousSpendingonOutputFigure3-33-3TheDeterminationofEquilibriumOutput25UsingaGraphAnincreaseinauUsingaGraphThefirst-roundincreaseindemand,shownbythedistanceABequals$1billion.Thisfirst-roundincreaseindemandleadstoanequalincreaseinproduction,or$1billion,whichisalsoshownbythedistanceinAB.Thisfirst-roundincreaseinproductionleadstoanequalincreaseinincome,shownbythedistanceinBC,alsoequalto$1billion.3-3TheDeterminationofEquilibriumOutput26UsingaGraphThefirst-roundiUsingaGraphThesecond-roundincreaseindemand,shownbythedistanceinCD,equals$1billiontimesthepropensitytoconsume.Thissecond-roundincreaseindemandleadstoanequalincreaseinproduction,alsoshownbythedistanceDC,andthusanequalincreaseinincome,shownbythedistanceDE.Thethird-roundincreaseindemandequals$c1billion,timesc1,themarginalpropensitytoconsume;itisequalto$c1

xc1

=$c12billion.3-3TheDeterminationofEquilibriumOutput27UsingaGraphThesecond-roundFollowingthislogic,thetotalincreaseinproductionafter,say,n+1

rounds,equals$1billionmultipliedbythesum:1+c1+c12+…+c1nSuchasumiscalledageometricseries.3-3TheDeterminationofEquilibriumOutputUsingaGraph28Followingthislogic,thetotaTosummarize:Anincreaseindemandleadstoanincreaseinproductionandacorrespondingincreaseinincome.Theendresultisanincreaseinoutputthatislargerthantheinitialshiftindemand,byafactorequaltothemultiplier.

Toestimatethevalueofthemultiplier,andmoregenerally,toestimatebehavioralequationsandtheirparameters,economistsuseeconometrics—asetofstatisticalmethodsusedineconomics.3-3TheDeterminationofEquilibriumOutputUsingWords29Tosummarize:3-3TheDeterminDescribingformallytheadjustmentofoutputovertimeiswhateconomistscallthedynamicsofadjustment.Supposethatfirmsmakedecisionsabouttheirproductionlevelsatthebeginningofeachquarter.Nowsupposeconsumersdecidetospendmore,thattheyincreasec0..Havingobservedanincreaseindemand,firmsarelikelytosetahigherlevelofproductioninthefollowingquarter.Inresponsetoanincreaseinconsumerspending,outputdoesnotjumptothenewequilibrium,butratherincreasesovertime.3-3TheDeterminationofEquilibriumOutputHowLongDoesItTakeforOutputtoAdjust?30DescribingformallytheadjustConsumerConfidenceandthe1990to1991RecessionAforecasterroristhedifferencebetweentheactualvalueofGDPandthevaluethathadbeenforecastbyeconomistsonequarterearlier.

Theconsumerconfidenceindexiscomputedfromamonthlysurveyofabout5,000householdswhoareaskedhowconfidenttheyareaboutbothcurrentandfutureeconomicconditions.31ConsumerConfidenceandthe19均衡所得變動(dòng)—民間部門乘數(shù)：自發(fā)支出(所得以外的因素引起)變動(dòng)會(huì)使均衡所得呈倍數(shù)變動(dòng)，稱為乘數(shù)效果。

ΔY＝ΔAEo×1/(1－c1)，乘數(shù)＝1/(1－c1)，邊際消費(fèi)傾向越大，乘數(shù)效果越大。引申：節(jié)儉矛盾(paradoxofthrift)大眾自發(fā)性儲(chǔ)蓄意願(yuàn)增加，結(jié)果整個(gè)社會(huì)儲(chǔ)蓄水準(zhǔn)並未增加。因?yàn)榇蟊娫黾幼园l(fā)性儲(chǔ)蓄(自發(fā)性消費(fèi)減少)，使均衡所得下降，誘發(fā)性儲(chǔ)蓄隨之減少，抵消了自發(fā)儲(chǔ)蓄。(如投資是所得的增函數(shù)，均衡所得下降後，均衡時(shí)的投資與儲(chǔ)蓄則下降)是依據(jù)凱因斯模型的結(jié)論：為需要面或支出面理論，及失業(yè)情況下。如依古典理論或經(jīng)濟(jì)處於充分就業(yè)下，節(jié)儉矛盾會(huì)產(chǎn)生嗎？32均衡所得變動(dòng)—民間部門乘數(shù)：自發(fā)支出(所得以外的因素引起)變ConsumerConfidenceandthe1990to1991RecessionTable1GDP,Consumption,andForecastErrors,1990-1991Quarter(1)Change

inRealGDP(2)Forecast

ErrorforGDP

(3)Forecast

Errorforc0(4)Indexof

ConsumerConfidence1990:21917231051990:329571901990:4638837611991:1312730651991:2274787733ConsumerConfidenceandthe193-4InvestmentEqualsSaving:AnAlternativeWayofThinkingaboutGoods-MarketEquilibriumSavingisthesumofprivatepluspublicsaving.Privatesaving(S),issavingbyconsumers.Publicsavingequalstaxesminusgovernmentspending.IfT>G,thegovernmentisrunningabudgetsurplus—publicsavingispositive.IfT<G,thegovernmentisrunningabudgetdeficit—publicsavingisnegative.343-4InvestmentEqualsSaving:Theequationabovestatesthatequilibriuminthegoodsmarketrequiresthatinvestmentequalssaving—thesumofprivatepluspublicsaving.ThisequilibriumconditionforthegoodsmarketiscalledtheISrelation.Whatfirmswanttoinvestmustbeequaltowhatpeopleandthegovernmentwanttosave.3-4InvestmentEqualsSaving:AnAlternativeWayofThinkingaboutGoods-MarketEquilibrium35TheequationabovestatesthatConsumptionandsavingdecisionsareoneandthesame.Theterm(1c1)iscalledthepropensitytosave.Inequilibrium:Rearrangingterms,wegetthesameresultasbefore:InvestmentEqualsSaving:AnAlternative

WayofThinkingaboutGoods-MarketEquilibrium36Consumptionandsavingdecisio求解均衡所得37求解均衡所得37TheParadoxofSavingTheparadoxofsaving(ortheparadoxofthrift)isthataspeopleattempttosavemore,theresultisbothadeclineinoutputandunchangedsaving.38TheParadoxofSavingTheparad均衡所得變動(dòng)—政府部門主旨：政府支出及租稅(均視為外生決定或自發(fā)性)等財(cái)政政策的對(duì)(均衡)所得的作用均衡：均衡所得基本上為自發(fā)支出×乘數(shù)

Y＝1/(1－c1)×(Co＋I(xiàn)o＋Go－c1To)乘數(shù)：政府支出乘數(shù)＝ΔY/ΔG＝1/(1－c1)租稅乘數(shù)＝ΔY/ΔT＝－c1/(1－c1)

平衡預(yù)算乘數(shù)＝1，在政府支出與租稅同額同向調(diào)整以保持預(yù)算平衡下，所得等額變動(dòng)。39均衡所得變動(dòng)—政府部門主旨：39穩(wěn)定或權(quán)宜性的財(cái)政政策穩(wěn)定財(cái)政政策(stabilizationfiscalpolicy)或權(quán)宜性的財(cái)政政策(discretionaryfiscalpolicy)景氣過熱，則採緊縮性財(cái)政政策，降低政府支出或提高租稅景氣衰退，則採擴(kuò)張性財(cái)政政策，增加政府支出或降低租稅緊縮缺口(deflationaryorrecessionarygap)：均衡所得低於充分就業(yè)之所得時(shí)，自發(fā)支出低於充分就業(yè)之支出水準(zhǔn)，稱之。此時(shí)，採增加政府支出或降低租稅(擴(kuò)張性財(cái)政政策)可解決。膨脹缺口(inflationarygap)：均衡所得高於充分就業(yè)之所得時(shí)，自發(fā)支出超過充分就業(yè)之支出水準(zhǔn)，稱之。此時(shí)，採降低政府支出或提高租稅(緊縮性財(cái)政政策)可解決(免除物價(jià)膨脹壓力)。40穩(wěn)定或權(quán)宜性的財(cái)政政策穩(wěn)定財(cái)政政策(stabilizatio自動(dòng)安定機(jī)能(built-instabilizer)指數(shù)財(cái)政制度中，具有可緩和景氣波動(dòng)或波幅的自我調(diào)節(jié)功能。誘發(fā)性租稅：如(累進(jìn))所得稅，當(dāng)景氣轉(zhuǎn)壞，可使消費(fèi)不致於下降太多，轉(zhuǎn)好時(shí)可免過熱。也可降低外生變數(shù)變動(dòng)對(duì)景氣影響程度，設(shè)T＝To＋tY時(shí)，自發(fā)支出乘數(shù)由1/(1－c1)縮小為1/(1－c1＋c1t)失業(yè)保險(xiǎn)制：不景氣時(shí)，失業(yè)家庭可獲救濟(jì)金，使失業(yè)家庭消費(fèi)不致於快速下降。41自動(dòng)安定機(jī)能(built-instabilizer)指數(shù)財(cái)3-5IstheGovernmentOmnipotent?

AWarningChanginggovernmentspendingortaxesisnotalwayseasy.

Theresponsesofconsumption,investment,imports,etc,arehardtoassesswithmuchcertainty.

Anticipationsarelikelytomatter.

Achievingagivenlevelofoutputcancomewithunpleasantsideeffects.

Budge