宏观经济学课件

TheClassicalLong RunModel 宏观经济学 2 TheClassicalLong RunModel EconomistssometimesdisagreewitheachotherActuallymuchmoreagreementexistsamongeconomiststhanthereappearstobeOncedistinctionbetweenlong runandshort runbecomesclearManyapparentdisagreementsamongmacroeconomistsdissolveIfnotimehorizonisspecified however aneconomistislikelytofocusonhorizonheorshefeelsismostimportantSomethingaboutwhicheconomistssometimesdodisagree 宏观经济学 3 TheClassicalLong RunModel Ideally wewouldlikeoureconomytodowellinbothlong runandshort runUnfortunately thereisoftenatrade offbetweenthesetwogoalsDoingbetterinshort runcanrequiresomesacrificeoflong rungoals andviceversaPolicesthatcanhelpussmoothouteconomicfluctuationsmayproveharmfultogrowthinthelong runWhilepoliciesthatpromiseahighrateofgrowthmightrequireustoputupwithmoreseverefluctuationsinshort run 宏观经济学 4 MacroeconomicModels ClassicalVersesKeynesian Classicalmodel developedbyeconomistsin19thandearly20thcenturies wasanattempttoexplainakeyobservationabouteconomyOverperiodsofseveralyearsorlonger economyperformsratherwellIfwethinkintermsofdecadesratherthanyearsorquarters businesscyclefadesinsignificanceIntheclassicalview thisbehaviorisnoaccidentPowerfulforcesareatworkthatdriveeconomytowardsfullemploymentAnimportantgroupofmacroeconomistscontinuestobelievethatclassicalmodelisusefuleveninshorterrunIn1936 inmidstofGreatDepression BritisheconomistJohnMaynardKeynesofferedanexplanationforeconomy spoorperformanceArguedthat whileclassicalmodelmightexplaineconomy soperationinlong run long runcouldbeaverylongtimeinarriving 宏观经济学 5 MacroeconomicModels ClassicalVersesKeynesian Keynesianideasbecameincreasinglypopularinuniversitiesandgovernmentagenciesduring1940sand1950sBymid 1960s entireprofessionhadbeenwonoverMacroeconomicswasKeynesianeconomicsClassicalmodelwasremovedfromvirtuallyallintroductoryeconomicstextbooksClassicalmodelisstillimportantInrecentdecadestherehasbeenanactivecounterrevolutionagainstKeynes sapproachtounderstandingthemacroeconomyUsefulinunderstandingeconomyoverlong runWhileKeynes sideasandtheirfurtherdevelopmenthelpusunderstandeconomicfluctuations movementsinoutputarounditslong runtrendClassicalmodelhasprovenmoreusefulinexplainingthelong runtrenditself 宏观经济学 6 AssumptionsoftheClassicalModel AllmodelsbeginwithassumptionsabouttheworldClassicalmodelisnoexceptionManyofitsassumptionsaresimplifyingMakemodelmoremanageable enablingustoseethebroadoutlinesofeconomicbehaviorwithoutgettinglostindetailsOneassumptioninclassicalviewthatgoesbeyondmeresimplificationMarketsclearPriceineverymarketwilladjustuntilquantitysuppliedandquantitydemandedareequal 宏观经济学 7 AssumptionsoftheClassicalModel Market clearingassumptionprovideshintaboutwhyclassicalmodeldoesabetterjoboverlongertimeperiods severalyearsormore thanshorteronesWe lluseclassicalmodeltoansweravarietyofimportantquestionsabouteconomyinlong run suchasHowistotalemploymentdetermined Howmuchoutputwillweproduce Whatroledoestotalspendingplayintheeconomy Whathappenswhenthingschange 宏观经济学 8 HowMuchOutputWillWeProduce Howcanwedisentanglewebofeconomicinteractionsweseearoundus Decidewhichmarketormarketsbestsuittheproblembeinganalyzed andIdentifybuyersandsellersIdentifytypeofenvironmentinwhichtheytradeButwhichmarketshouldwestartwith LogicalstartismarketforresourcesLabor landandnaturalresources capitalandentrepreneurshipWe llconcentrateourattentiononlaborOurquestionisHowmanyworkerswillbeemployedintheeconomy 宏观经济学 9 Figure1 TheLaborMarket 宏观经济学 10 TheLaborMarket LaborsupplycurveslopesupwardBecause aswagerateincreases moreandmoreindividualsarebetteroffworkingthannotworkingThus ariseinwagerateincreasesnumberofpeoplewhowanttowork tosupplytheirlaborAswagerateincreaseseachfirmwillfindthat tomaximizeprofit itshouldemployfewerworkersthanbeforeWhenallfirmsbehavethiswaytogetherariseinwageratewilldecreasequantityoflabordemandedThisiswhyeconomy slabordemandcurveslopesdownwardInclassicalview economyachievesfullemploymentonitsown 宏观经济学 11 DeterminingtheEconomy sOutput Mosteffectivewaytomasteramacroeconomicmodelis divideandconquer Startwithpartofmodel understanditwell andthenaddinotherpartsAccordingly ourclassicalanalysisofeconomyisdividedintotwoseparatequestionsWhatwouldbethelong runequilibriumoftheeconomyiftherewereaconstantstateoftechnologyAndifquantitiesofallresourcesbesideslaborwerefixed Whathappenstothislong runequilibriumwhentechnologyandquantitiesofotherresourceschange 宏观经济学 12 TheProductionFunction RelationshipbetweentotalemploymentandtotalproductionintheeconomyGivenbyeconomy saggregateproductionfunctionShowstotaloutputeconomycanproducewithdifferentquantitiesoflaborGivenconstantamountsofotherresourcesandcurrentstateoftechnologyInclassical long runvieweconomyreachesitspotentialoutputautomaticallyAnimportantconclusionofclassicalmodelandanimportantcharacteristicoftheeconomyinlong runOutputtendstowarditspotential full employmentlevelonitsown withnoneedforgovernmenttosteertheeconomytowardit 宏观经济学 13 Figure2 OutputDeterminationintheClassicalModel 宏观经济学 14 TheRoleofSpending Whatifbusinessfirmsareunabletosellalloutputproducedbyafullyemployedlaborforce EconomywouldnotbeabletosustainfullemploymentforverylongIfweareassertingthatpotentialoutputisanequilibriumfortheeconomyHadbetterbesurethattotalspendingonoutputisequaltototalproductionduringtheyearButcanwebesureofthis Inclassicalviewanswerisyes 宏观经济学 15 TotalSpendinginaVerySimpleEconomy ImagineaworldwithjusttwotypesofeconomicunitsHouseholdsandbusinessfirmsCircularFlowAdiagramthatshowshowgoods resources anddollarpaymentsflowbetweenhouseholdsandfirmsInasimpleeconomywithjusthouseholdsandfirmsinwhichhouseholdsspendalloftheirincomeTotalspendingmustbeequaltototaloutputKnownasSay sLaw 宏观经济学 16 Figure3 TheCircularFlow 宏观经济学 17 TotalSpendinginaVerySimpleEconomy Say sLawnamedafterclassicaleconomistJeanBaptisteSay 1767 1832 whopopularizedtheideaInSay sownwords Aproductisnosoonercreatedthanit fromthatinstant affordsamarketforotherproductstothefullextentofitsownvalue Thus themerecircumstanceofthecreationofoneproductimmediatelyopensaventforotherproducts Say slawstatesthatbyproducinggoodsandservicesFirmscreateatotaldemandforgoodsandservicesequaltowhattheyhaveproducedorSupplycreatesitsowndemand 宏观经济学 18 TotalSpendinginaMoreRealisticEconomy DoesSay slawalsoapplyinamorerealisticeconomy IntherealworldHouseholdsdon tspendalltheirincomeRather someoftheirincomeissavedorgoestopaytaxesHouseholdsarenottheonlyspendersintheeconomyBusinessesandgovernmentbuysomeofthefinalgoodsandservicesweproduceInadditiontomarketsforgoodsandresources thereisalsoaloanablefundsmarketWherehouseholdsavingismadeavailabletoborrowersinbusinessorgovernmentsectors 宏观经济学 19 SomeNewMacroeconomicVariables Plannedinvestmentspending IP overaperiodoftimeistotalinvestmentspending I minuschangeininventoriesovertheperiodIP I inventoriesNettaxes T aretotalgovernmenttaxrevenueminusgovernmenttransferpaymentsT totaltaxrevenue transfersHouseholdsaving S It softenusefultoarriveathouseholdsavingintwostepsDeterminehowmuchincomehouseholdsectorhasleftafterpaymentofnettaxesHouseholdsector sdisposableincomeDisposableIncome TotalIncome NetTaxesPartthatisnotspentisdefinedassaving S S DisposableIncome CTotalSpendinginClassicaInClassica totalspendingissumofpurchasesmadebyhouseholdsector C businesssector IP andgovernmentsector G Totalspending C IP G 宏观经济学 20 SomeNewMacroeconomicVariables SavingandnettaxesarecalledleakagesoutofspendingAmountofincomethathouseholdsreceive butdonotspendTherearealsoinjections spendingfromsourcesotherthanhouseholdsAgovernment spurchasesofgoodsandservicesPlannedinvestmentspending IP TotalspendingwillequaltotaloutputifandonlyiftotalleakagesintheeconomyareequaltototalinjectionsOnlyifsumofsavingandnettaxesisequaltosumofplannedinvestmentspendingandgovernmentpurchases 宏观经济学 21 Figure4 LeakagesandInjections 宏观经济学 22 TheLoanableFundsMarket WherehouseholdsmaketheirsavingavailabletothosewhoneedadditionalfundsTotalsupplyofloanablefundsisequaltohouseholdsavingFundssuppliedareloanedout andhouseholdsreceiveinterestpaymentsonthesefundsBusinesses demandforloanablefundsisequaltotheirplannedinvestmentspendingFundsobtainedareborrowed andfirmspayinterestontheirloansBudgetdeficitExcessofgovernmentpurchasesovernettaxesBudgetofsurplusExcessofnettaxesovergovernmentpurchasesWhengovernmentpurchasesofgoodsandservices G aregreaterthannettaxes T GovernmentrunsabudgetdeficitequaltoG TWhengovernmentpurchasesofgoodsandservices G arelessthannettaxes T GovernmentrunsabudgetsurplusequaltoT G 宏观经济学 23 TheSupplyofFundsCurve SinceinterestisrewardforsavingandsupplyingfundstofinancialmarketRiseininterestrateincreasesquantityoffundssupplied householdsaving whileadropininterestratedecreasesitSupplyoffundscurveIndicateslevelofhouseholdsavingatvariousinterestratesQuantityoffundssuppliedtothefinancialmarketdependspositivelyoninterestrateThisiswhythesaving orsupplyoffunds curveslopesupwardOtherthingscanaffectsavingsbesidestheinterestrate includingTaxratesExpectationsaboutthefutureGeneralwillingnessofhouseholdstopostponeconsumption 宏观经济学 24 Figure5 SupplyofHouseholdLoanableFunds 宏观经济学 25 TheDemandforFundsCurve WheninterestratefallsinvestmentspendingandthebusinessborrowingneededtofinanceitriseBusinessdemandforfundscurveslopesdownwardWhataboutgovernment sdemandforfunds Willit too beinfluencedbytheinterestrate ProbablynotverymuchGovernmentseemstobecushionedfromcost benefitconsiderationsthathauntbusinessdecisionsAnycompanypresidentwhoignoredinterestratesindecidinghowmuchtoborrowwouldbequicklyoutofajobU S presidentsandlegislatorshaveoftendonesowithlittlepoliticalcostGovernmentsector sdeficitanditsdemandforfundsareindependentofinterestrateAsinterestratedecreasesquantityoffundsdemandedbybusinessfirmsincreasesWhilequantitydemandedbygovernmentremainsunchangedTherefore totalquantityoffundsdemandedrises 宏观经济学 26 Figure6 BusinessDemandforLoanableFunds 宏观经济学 27 Figure7 TheDemandforFunds 宏观经济学 28 EquilibriumintheLoanableFundsMarket InclassicalviewloanablefundsmarketisassumedtoclearInterestratewillriseorfalluntilquantitiesoffundssuppliedanddemandedareequalCanwebesurethatalloutputproducedatfullemploymentwillbepurchased 宏观经济学 29 Figure8 LoanableFundsMarketEquilibrium 宏观经济学 30 TheLoanableFundsMarketandSay sLaw Aslongasloanablefundsmarketclears Say slawholdsTotalspendingequalstotaloutputThisistrueeveninamorerealisticeconomywithsaving taxes investmentandgovernmentdeficitHere sanotherwaytoseethesameresult intermsofasimpleequationLoanablefundsmarketclears S IP G T RearrangingthisequationbymovingTtoleftsideLoanablefundsmarketclears S T IP GSay slawshowsthattotalvalueofspendingineconomywillequaltotalvalueofoutputRulesoutageneraloverproductionorunderproductionofgoodsintheeconomyItdoesnotpromiseusthateachfirmwillbeabletosellalloftheparticulargooditproduces 宏观经济学 31 Figure9 AnExpandedCircularFlow 宏观经济学 32 TheClassicalModel ASummary BeganwithacriticalassumptionAllmarketsclearInclassicalmodel governmentneedn tworryaboutemploymentEconomywillachievefullemploymentonitsownInclassicalmodel governmentneedn tworryabouttotalspendingEconomywillgeneratejustenoughspendingonitsowntobuyoutputthatafullyemployedlaborforceproduces 宏观经济学 33 UsingtheTheory FiscalPolicyintheClassicalModel Couldgovernmentincreaseeconomy stotalemploymentandtotaloutputbyraisingtotalspending TwoideasforincreasingspendingcometomindGovernmentcouldsimplypurchasemoreoutputitselfMoregoods liketanksandpolicecars ormoreservices likethoseprovidedbyhighschoolteachersandjudgesGovernmentcouldcutnettaxes lettinghouseholdskeepmoreoftheirincomeSotheywouldspendmoreonfood clothing furniture newcars andsoonFiscalpolicyisachangeingovernmentpurchasesor