宏观经济学---曼昆chap03.ppt

宏观经济学---曼昆chap03.ppt

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NationalIncome:

WhereitComesFromandWhereitGoesChapter3Zhao,QiweiEconomicsandManagementSchool,WHUCHAPTER3NationalIncomeInthischapter,youwilllearnlwhatdeterminestheeconomystotaloutput/incomelhowthepricesofthefactorsofproductionaredeterminedlhowtotalincomeisdistributedlwhatdeterminesthedemandforgoodsandserviceslhowequilibriuminthegoodsmarketisachievedCHAPTER3NationalIncomeOutlineofmodelAclosedeconomy,market-clearingmodelSupplysidemfactormarkets（supply,demand,price）mdeterminationofoutput/incomeDemandsidemdeterminantsofC,I,andGEquilibriummgoodsmarketmloanablefundsmarketFigure3.1TheCircularFlowofDollarsThroughtheEconomyCHAPTER3NationalIncomeAnEconomysOutputDependson1）Quantityofinputs,Factorsofproduction2）Abilitytoturninputsintooutput,productionfunction.CHAPTER3NationalIncomeFactorsofproductionK=capital:

tools,machines,andstructuresusedinproductionL=labor:

thephysicalandmentalefforts（time）ofworkers-Weassumethat1）KandLasgiven,i.e.,fixed,and2）fullyutilized（nounemployment）.Cf）Land,Materials,Energy,CHAPTER3NationalIncomeTheproductionfunctionldenotedY=F（K,L）lshowshowmuchoutput（Y）theeconomycanproducefromKunitsofcapitalandLunitsoflaborlreflectstheeconomysleveloftechnologylexhibitsconstantreturnstoscale（closelyrelatedtoincomedistribution!

）CHAPTER3NationalIncomeReturnstoscale:

AreviewInitiallyY1=F（K1,L1）Scaleallinputsbythesamefactorz:

K2=zK1andL2=zL1（e.g.,ifz=1.25,thenallinputsareincreasedby25%）Whathappenstooutput,Y2=F（K2,L2）?

lIfconstantreturnstoscale,Y2=zY1lIfincreasingreturnstoscale,Y2zY1lIfdecreasingreturnstoscale,Y20CHAPTER3NationalIncomeExample2decreasingreturnstoscaleforanyz1CHAPTER3NationalIncomeExample3increasingreturnstoscaleforanyz1CHAPTER3NationalIncomeAssumptionsofthemodel1.Technologyisfixed.2.TheeconomyssuppliesofcapitalandlaborarefixedatCHAPTER3NationalIncomeDeterminingGDPOutputisdeterminedbythefixedfactorsuppliesandthefixedstateoftechnology:

IncreaseinKandLandimprovementsintheproductiontechnologyleadtogrowthintheeconomysoutput（Chapter7and8）.CHAPTER3NationalIncomeThedistributionofnationalincomeldeterminedbyfactorprices,thepricesperunitthatfirmspayforthefactorsofproductionmwage=priceofLmrentalrate=priceofKCHAPTER3NationalIncomeNotationW=nominalwageR=nominalrentalrateP=priceofoutputW/P=realwage（measuredinunitsofoutput）R/P=realrentalrateCHAPTER3NationalIncomeHowfactorpricesaredeterminedlFactorpricesaredeterminedbysupplyanddemandinfactormarkets.lRecall:

Supplyofeachfactorisfixed.lWhataboutdemand?

Figure3.2HowaFactorofProductionIsCompensatedCHAPTER3NationalIncomeDemandforlaborlAssumemarketsarecompetitive:

eachfirmtakesW,R,andPasgiven.lBasicidea:

Afirmusesfactorsofproductiontomaximizeprofit.lProfit=Revenue-LaborCosts-CapitalCosts=PYWLRK=PF（K,L）WL-RKCHAPTER3NationalIncomeMarginalproductoflabor（MPL）ldefinition:

Theextraoutputthefirmcanproduceusinganadditionalunitoflabor（holdingotherinputsfixed）:

MPL=F（K,L+1）F（K,L）CHAPTER3NationalIncomeExercise:

Compute&graphMPLa.DetermineMPLateachvalueofL.b.Graphtheproductionfunction.c.GraphtheMPLcurvewithMPLontheverticalaxisandLonthehorizontalaxis.LYMPL00n.a.110?

219?

3278434?

540?

645?

749?

852?

954?

1055?

CHAPTER3NationalIncomeAnswers:

CHAPTER3NationalIncomeYoutputMPLandtheproductionfunctionLlabor1MPL1MPL1MPLAsmorelaborisadded,MPLSlopeoftheproductionfunctionequalsMPLCHAPTER3NationalIncomeDiminishingmarginalproductlAsafactorinputisincreased,itsmarginalproductfalls（otherthingsequal）.lIntuition:

SupposeLwhileholdingKfixedfewermachinesperworkerlowerworkerproductivityCHAPTER3NationalIncomeCheckyourunderstanding:

lWhichoftheseproductionfunctionshavediminishingmarginalreturnstolabor?

CHAPTER3NationalIncomeDemandforLaborlFirmsgoal:

maximizeprofits.lQ.Hireadditionalunitoflaborornot?

lA.Lookatitseffectsonprofit!

lCompareextrarevenuefromextraoutputproducedbytheextraunitoflabortoextracostofhigherspendingonwagesCHAPTER3NationalIncomeDemandforLaborlExtrarevenuefromextraoutputproducedbytheextraunitoflabor=MPL*PlExtracostofhigherspendingonwages=WlChangeofProfit=MPL*PWlFirmscontinuetohireadditionalunitoflaborif0.Theystopif=0.lHence,wegetlorCHAPTER3NationalIncomeMPLandthedemandforlaborEachfirmhireslaboruptothepointwhereMPL=W/P.UnitsofoutputUnitsoflabor,LMPL,LabordemandRealwageQuantityoflabordemandedCHAPTER3NationalIncomeTheequilibriumrealwageTherealwageadjuststoequatelabordemandwithsupply.UnitsofoutputUnitsoflabor,LMPL,LabordemandequilibriumrealwageLaborsupplyCHAPTER3NationalIncomeExercise（part2）Suppo