曼昆宏观经济学第七版笔记.docx
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曼昆宏观经济学第七版笔记
曼昆宏观经济学第七版笔记.txt我们用一只眼睛看见现实的灰墙,却用另一只眼睛勇敢飞翔,接近梦想。
男人喜欢听话的女人,但男人若是喜欢一个女人,就会不知不觉听她的话。
EditedbyShuKaichuangMacroeconomics免费版
2010-11-26
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Context
I.Introduction3
II.NationalIncomes4
III.MoneyandInflation7
IV.TheOpenEconomy12
V.Unemployment17
VI.EconomicGrowthI20
VII.EconomicGrowthII24
VIII.IntroductiontoEconomicfluctuations27
IX.AggregateDemandI32
X.AggregateDemandII38
XI.AggregateDemandintheOpenEconomy44
XII.AggregateSupply50
XIII.ADynamicModelofAggregateDemandandAggregateSupply55
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Introduction
QuestionsMacroeconomicswantstoanswer
Whyhavesomecountriesexperiencedrapidgrowthinincomesoverthepastcenturywhileothersstaymiredinpoverty?
Whydosomecountrieshavehighratesofinflationwhileothersmaintainstableprices?
Whydoallcountriesexperiencerecessionsanddepressions—recurrentperiodsoffallingincomesandrisingunemployment—andhowcangovernmentpolicyreducethefrequencyandseverityoftheseepisodes?
MajorMarkets
Goodsandservicesmarket
Moneymarket
Factormarket
Labormarket
Internationalmarket
Data
Majordata
GDP
Inflationrateandmoneysupply
Unemploymentrate
Netexportandexchangerate
Nominalversusrealdata
Models
Abstractionoftherealworld
Mathematicandmodels
Endogenousvariablesandexogenousvariables
Assumptionsofmodels
Structure
ClassicalTheory
Marketclearing
Priceflexibility
GrowthTheory
Emphasisthegrowthofcapital,laborandtechnology
Explainhoweconomyevolvesoverdecades
BusinessCycleTheory
Studyfluctuationinshort-term
Marketisnotclearing
NationalIncomes
GoodsandServices
Factorsofproductionaretheinputsusedtoproducegoodsandservices.
Capital(K)
Labor(L)
Theproductionfunction:
Y=F(K,L)
Constantreturntoscale:
toanyz,
zY=F(zK,zL)
NationalIncomeDistribution
Factorpricesaretheamountspaidtothefactorsofproduction—thewageworkersearnandtherenttheownersofcapitalcollect.
Wage(W)
CapitalRent(R)
Considerlabor,holdingcapitalconstant
Theprofits:
Profits=PY-WL-RK
Themarginalproductoflabor(MPL)istheextraamountofoutputthefirmgetsfromoneextraunitoflabor.
Diminishingmarginalproduct:
holdingtheamountofcapitalfixed,themarginalproductoflabordecreasesastheamountoflaborincreases.
CaseStudy:
TheBlackDeathandFactorPrices
Aswehavejustlearned,intheneoclassicaltheoryofdistribut-ion,factorpricesequalthemarg-inalproductsofthefactorsofproduction.Becausethemargi-nalproductsdependonthequantitiesofthefactors,achangeinthequantityofanyonefactoraltersthemarginalproductsofalltheactors.Therefore,achangeinthesupplyofafactoraltersequilibriumfactorprices.
Fourteenth-centuryEuropeprovidesavividexampleofhowfactorquantitiesaffectfactorprices.Theoutbreakofthebubonicplague—theBlackDeath—in1348reducedthepopulationofEuropebyaboutone-thirdwithinafewyears.Becausethemarginalproductoflaborincreasesastheamountoflaborfalls,thismassivereductioninthelaborforceraisedthemarginalproductoflabor.Realwagesdidincreasesubstantiallyduringtheplagueyears—doubling,bysomeestimates.Thepeasantswhowerefortunateenoughtosurvivetheplagueenjoyedeconomicprosperity.
Thereductioninthelaborforcecausedbytheplaguealsoaffectedthereturntoland,theothermajorfactorofproductioninmedievalEurope.Withfewerworkersavailabletofarmtheland,anadditionalunitoflandproducedlessadditionaloutput.Thisfallinthemarginalproductoflandledtoadeclineinrealrentsof50percentormore.Thus,whilethepeasantclassesprospered,thelandedclassessufferedreducedincomes.
Holdingcapitalconstant,then:
ΔProfit=ΔRevenue-ΔCost=(P×MPL)-W.
ThecompanywilladdlaboruntilΔProfit=0,atthattime,
MPL=W/P
Copytheprocess,ifweconsidercapital,thecompanywilladdcapitaluntil
MPK=R/P
WecallW/Pasrealwage,andR/Pasrealrentalpriceofcapital.
Theincomethatremainsafterthefirmshavepaidthefactorsofproductionistheeconomicprofitoftheownersofthefirms.
EconomicProfit=Y-(MPL*L)-(MPK*K).
Iftheproductionfunctionhasthepropertyofconstantreturnstoscale,then,
z*Y=Economicprofits+z*MPL*L+z*MPK*K
Differentiatewithrespecttoz,
F(L,K)=MPL*L+MPK*K
DemandforGoodsandServices
Aclosedeconomyhasthreeusesforthegoodsandservicesitproduces.
Y=C+I+G
Consumption
Disposableincome:
incomeafterthepaymentofalltaxes,Y?
T.
C=C(Y-T)
Marginalpropensitytoconsume(MPC):
theamountbywhichconsumptionchangeswhendisposableincomeincreasesbyonedollar.
Investment
Thequantityofinvestmentgoodsdemandeddependsontheinterestrate.I=I(r).
Iftheinterestraterises,fewerinvestmentprojectsareprofitable,andthequantityofinvestmentgoodsdemandedfalls.
GovernmentPurchases(holdingconstant)
Governmentspending
Transferpayments
Equilibrium
EquilibriumintheMarketforGoodsandServices:
Y=C(Y-T)+I(r)+G
EquilibriumintheFinancialMarkets:
S=I
MoneyandInflation
Money
Moneyisthestockofassetsthatcanbereadilyusedtomaketransactions.
TheFunctionsofMoney
Storeofvalue
Unitofaccount
Mediumoftransaction
TheTypesofMoney
Commoditymoney
Fiatmoney
CaseStudy:
MoneyinaPOWCamp
MoneyandSocialConventionsontheIslandofYapTheeconomyofYap,asmallislandinthePacific,oncehadatypeofmoneythatwassomethingbetweencommodityandfiatmoney.ThetraditionalmediumofexchangeinYapwasfei,stonewheelsupto12feetindiameter.Thesestoneshadholesinthecentersothattheycouldbecarriedonpolesandusedforexchange.
Largestonewheelsarenotaconvenientformofmoney.Thestoneswereheavy,soittooksubstantialeffortforanewownertotakehisfeihomeaftercompletingatransaction.Althoughthemonetarysystemfacilitatedexchange,itdidsoatgreatcost.
Eventually,itbecamecommonpracticeforthenewownerofthefeinottobothertotakephysicalpossessionofthestone.Instead,thenewowneracceptedaclaimtothefeiwithoutmovingit.Infuturebargains,hetradedthisclaimforgoodsthathewanted.Havingphysicalpossessionofthestonebecamelessimportantthanhavinglegalclaimtoit.
Thispracticewasputtoatestwhenavaluablestonewaslostatseaduringastorm.Becausetheownerlosthismoneybyaccidentratherthanthroughnegligence,everyoneagreedthathisclaimtothefeiremainedvalid.Evengenerationslater,whennoonealivehadeverseenthisstone,theclaimtothisfeiwasstillvaluedinexchange.
Moneyquantity
Thequantityofmoneyavailableiscalledthemoneysupply.
Thecontroloverthemoneysupplyiscalledmonetarypolicy.
Measureofmoney
TheQuantityTheoryofMoney
TransactionsandtheQuantityEquation
MV=PT
FromTransactionstoIncome
MV=PY
TheMoneyDemandFunctionandthequantityEquation
Realmoneybalance:
M/P
Moneydemandfunction:
(M/P)^(d)=kY
Noticethat(M/P)d=M/P,andMV=PY,therefore,V=1/k.
TheAssumptionofConstantVelocity
Quantitytheoryofmoney
Ifvelocityisfixed,thequantityofmoneydeterminesthedollarvalueoftheeconomy’soutput.
Money,Prices,andInflation
%ChangeinM+%ChangeinV=%ChangeinP+%ChangeinY.
Thequantitytheoryofmoneystatesthatthecentralbank,whichcontrolsthemoneysupply,hasultimatecontrolovertherateofinflation.Ifthecentralbankkeepsthemoneysupplystable,thepricelevelwillbestable.Ifthecentralbankincreasesthemoneysupplyrapidly,thepricelevelwillriserapidly
CaseStudy:
InflationandMoneyGrowth
“Inflationisalwaysandeverywhereamonetaryphenomenon.’’SowroteMiltonFriedman,thegreateconomistwhowontheNobelPrizeineconomicsin1976.
Thequantitytheoryofmoneyleadsustoagreethatthegrowthinthequantityofmoneyistheprimarydeterminantoftheinflationrate.YetFriedman’sclaimisempirical,nottheoretical.Toevaluatehisclaim,andtojudgetheusefulnessofourtheory,weneedtolookatdataonmoneyandprices.
Figureaboveexaminesthesamequestionwithinternationaldata.Itshowstheaveragerateofinflationandtheaveragerateofmoneygrowthinmorethan100countriesduringtheThelinkbetweenmoneygrowthandinflationclear.Countrieswithhighmoneygrowthtendtohavehighin?
ation,andcountrieswithlowmoneygrowthtendtohavelowinflation.
Seigniorage
Therevenueraisedthroughtheprintingofmoneyiscalledseigniorage.
Printmoney→moneysupplyincrease→inflation
Inflationtax
CaseStudy:
PayingfortheAmericanRevolution
AlthoughseignioragehasnotbeenamajorsourceofrevenuefortheU.S.governmentinrecenthistory,thesituationwasverydifferenttwocenturiesago.Beginningin1775theContinentalCongressneededtofindawaytofinancetheRevolution,butithadlimitedabilitytoraiserevenuethroughtaxation.It,therefore,reliedontheprintingoffiatmoneytohelppayforthewar.
TheContinentalCongress’srelianceonseigniorageincreasedovertime.In1775newissuesofcontinentalcurrencywereabout$6million.Thisamountincreasedto$19millionin1776,$13millionin1777,$63millionin1778,and$125millionin1779.
Notsurprisingly,thisrapidgrowthinthemoneysupplyledtomassiveinflation.Attheendofthewar,thepriceofgoldmeasuredincontinentaldollarswasmorethan100timesitslevelofonlyafewyearsearlier.Thelargequantityofthecontinentalcurrencymadethecontinentaldollarnearlyworthless.Thisexperiencealsogavebirthtoaonce-popularexpression:
peopleusedtosaysomethingwa