巴罗 宏观经济学 11

Inflation,MoneyGrowth,andInterestRatesChapter111.Cross-CountryDataonInflationandMoneyGrowthKeyequation:Ms

=P·L(Y,i)Twopossiblereasonsofinflation:DecreaseofrealdemandformoneyIncreaseofmoneysupply2.Cross-CountryDataonInflationandMoneyGrowthInflationratesandmoneygrowthratesfor82countriesfrom1960to2000.Wemeasurethepricelevel,P,bytheconsumerpriceindex(CPI).WeusetheCPI,ratherthantheGDPdeflator,becauseofdataavailability.3.4.5.6.Cross-CountryDataonInflationandMoneyGrowthHighlightsTheinflationratewasgreaterthan0forallcountriesfrom1960to2000Thegrowthrateofnominalcurrencywasgreaterthan0forallcountriesfrom1960to2000.Thereisabroadcross-sectionalrangefortheinflationratesandthegrowthratesofmoney.7.Cross-CountryDataonInflationandMoneyGrowthHighlightsThemedianinflationratefrom1960to2000was8.3%peryear,with30countriesexceeding10%.Forthegrowthrateofnominalcurrency,themedianwas11.6%peryear,with50above10%8.Cross-CountryDataonInflationandMoneyGrowthHighlightsInmostcountries,thegrowthrateofnominalcurrency,M,exceededthegrowthrateofprices.Foracountrythathasahighinflationrateinoneperiodtohaveahighinflationrateinanotherperiod.Strongpositiveassociationbetweentheinflationrateandthegrowthrateofnominalcurrency.9.Cross-CountryDataonInflationandMoneyGrowth10.Cross-CountryDataonInflationandMoneyGrowthOnelessonfromthecross-countrydataisthat,tounderstandinflation,wehavetoincludemoneygrowthasacentralpartoftheanalysis.MiltonFriedman’sfamousdictum:“Inflationisalwaysandeverywhereamonetaryphenomenon.〞11.InflationandInterestRatesActualandExpectedInflationLetπbetheinflationrate.Theinflationratefromyear1toyear2,π1,istheratioofthechangeinthepriceleveltotheinitialpricelevel.π1=(P2−P1)/P1π1=∆P1/P112.InflationandInterestRatesActualandExpectedInflationπ1=(P2−P1)/P1π1=∆P1/P1π1

·P1=P2−P1P2=(1+π1)·P113.InflationandInterestRatesActualandExpectedInflationSincethefutureisunknown,householdshavetoformforecastsorexpectationsofinflation.Denotebyπe1theexpectationoftheinflationrateπ1.Theactualinflationrate,π1,willusuallydeviatefromitsexpectation,πe1,andtheforecasterror—orunexpectedinflation—willbenonzero.14.InflationandInterestRatesActualandExpectedInflationHouseholdstrytokeeptheerrorsassmallaspossible.Therefore,theyuseavailableinformationonpastinflationandothervariablestoavoidsystematicmistakes.Expectationsformedthiswayarecalledrationalexpectations.15.InflationandInterestRatesRealandNominalInterestRatesThedollarvalueofassetsheldasbondsrisesovertheyearbythefactor1+i1.Theinterestratei1isthedollarornominalinterestratebecausei1determinesthechangeovertimeinthenominalvalueofassetsheldasbonds.16.InflationandInterestRates17.InflationandInterestRatesRealandNominalInterestRatesTheRealinterestratetobetherateatwhichtherealvalueofassetsheldasbondschangesovertime.dollarassetsinyear2=(dollarassetsinyear1)·(1+i1)P2=P1

·(1+π1)18.InflationandInterestRatesRealandNominalInterestRates(dollarassetsinyear2/P2)=(dollarassetsinyear1/P1)·

(1+i1)/(1+π1)realassetsinyear2=(realassetsinyear1)·(1+i1)/(1+π1)19.InflationandInterestRatesRealandNominalInterestRatesSincetherealinterestrate,denotedbyr1,istherateatwhichassetsheldasbondschangeinrealvalue:(1+r1)=(1+i1)/(1+π1)20.InflationandInterestRatesRealandNominalInterestRatesr1=i1−π1−r1·π1thecrossterm,r1

·π1,whichtendstobesmall;realinterestrate=nominalinterestrate−inflationrater1=i1−π121.InflationandInterestRatesFisherEquationi=r+πFisherEffecti

π

22.InflationandInterestRatesTheRealInterestRateandIntertemporalSubstitutionWhentheinflationrate,π,isnotzero,itistherealinterestrate,r,ratherthanthenominalrate,i,thatmattersforintertemporalsubstitution.23.InflationandInterestRatesActualandExpectedRealInterestRatesTheexpectedinflationratedeterminestheexpectedrealinterestrate,ret

ret

=it−πetexpectedrealinterestrate=nominalinterestrate−expectedinflationrate24.InflationandInterestRatesMeasuringexpectedinflationAskasampleofpeopleabouttheirexpectations.Usethehypothesisofrationalexpectations,whichsaysthatexpectationscorrespondtooptimalforecasts,giventheavailableinformation.Thenusestatisticaltechniquestogaugetheseoptimalforecasts.Usemarketdatatoinferexpectationsofinflation25.InflationandInterestRatesMeasuringexpectedinflationLivingstonSurveyAskasampleofpeople〔50economists〕abouttheirexpectations.26.InflationandInterestRates27.InflationandInterestRates28.InflationandInterestRatesMeasuringexpectedinflationIndexedbonds,realinterestrates,andexpectedinflationratesIndexedgovernmentbonds,whichadjustnominalpayoutsofinterestandprincipalforchangesinconsumer-priceindexes.Thesebondsguaranteetherealinterestrateoverthematurityofeachissue.29.InflationandInterestRates30.InflationandInterestRates31.InflationandInterestRatesInterestRatesonMoneyrealinterestrateonmoney=

nominalinterestrateonmoney−πtrealinterestrateonmoney=−πt32.InflationintheEquilibriumBusiness-CycleModelGoalsToseehowinflationaffectsourconclusionsaboutthedeterminationofrealvariables,includingrealGDP,consumptionandinvestment,quantitiesoflaborandcapitalservices,therealwagerate,andtherealrentalprice.Tounderstandthecausesofinflation.33.InflationintheEquilibriumBusiness-CycleModelAssumefullyanticipatedinflation,sothattheinflationrate,πt,equalstheexpectedrate,πet

.Extendtheequilibriumbusiness-cyclemodeltoallowformoneygrowth.34.InflationintheEquilibriumBusiness-CycleModelAssumethegovernmentprintsnewcurrencyandgivesittopeople.Theyreceiveatransferpaymentfromthegovernment.Thepaymentsarelump-sumtransfers,meaningthattheamountreceivedisindependentofhowmuchthehouseholdconsumesandworks,howmuchmoneythehouseholdholds,andsoon.35.InflationintheEquilibriumBusiness-CycleModelIntertemporal-SubstitutionEffectsTheexpectedrealinterestrate,ret

,hasintertemporal-substitutioneffectsonconsumptionandlaborsupply.Therefore,forgivenit,achangeinπt

willhavetheseintertemporal-substitutioneffects.36.InflationintheEquilibriumBusiness-CycleModelBondsandCapitali=(R/P)·κ−δ(κ)Replacethenominalinterestrateonbonds,i,bytherealrate,r,r=(R/P)·κ−δ(κ)37.InflationintheEquilibriumBusiness-CycleModelInterestRatesandtheDemandforMoneyThetradeoffbetweenearningassetsandholdingmoneyis(i

−π)−(−π)=iTherefore,thenominalinterestrate,i,stilldeterminesthecostofholdingmoneyratherthanearningassets.WecanthereforestilldescriberealmoneydemandbythefunctionMd/P=L(Y,i)38.InflationintheEquilibriumBusiness-CycleModelInterestRatesandtheDemandforMoneyItistherealinterestrate,r,thathasintertemporal-substitutioneffectsonconsumptionandlaborsupply.Itisthenominalinterest,i,thatinfluencestherealdemandformoney,Md/P.39.InflationintheEquilibriumBusiness-CycleModel40.InflationintheEquilibriumBusiness-CycleModel41.InflationintheEquilibriumBusiness-CycleModelInflationandtheRealEconomyAchangeintheinflationrate,π,doesnotshiftthedemandorsupplycurveforcapitalservices.Therefore,(R/P)*and(κK)*donotchange.Achangeintheinflationrate,π,doesnotshiftthedemandorsupplycurveforlabor.Therefore,(w/P)*andL*donotchange.42.InflationintheEquilibriumBusiness-CycleModelInflationandtheRealEconomyRealGDP,Y,isdeterminedbytheproductionfunctionY=A·F(κK,L)WeconcludethatachangeinπdoesnotinfluencerealGDP,Y.43.InflationintheEquilibriumBusiness-CycleModelInflationandtheRealEconomyTherealrentalprice,R/P,andthecapitalutilizationrate,κ,determinetherealrateofreturnfromowningcapital,(R/P)·κ−δ(κ),andthereforetherealinterestrate,r,

r=(R/P)·κ−δ(κ).SinceR/Pandκareunchanged,wefindthatachangeintheinflationrate,π,doesnotaffecttherealinterestrate,r.44.InflationintheEquilibriumBusiness-CycleModelInflationandtheRealEconomyIfwecontinuetoignoreincomeeffectsfrominflation,π,weknowthatCdoesnotchange.SinceYisfixed,weconcludethatIdoesnotchange.45.InflationintheEquilibriumBusiness-CycleModelWehavefoundthatthetimepathsofmoneygrowthandinflationdonotaffectagroupofrealvariables.ThisgroupcomprisesrealGDP,Y;inputsoflaborandcapitalservices,LandκK;consumptionandinvestment,CandI;therealwagerate,w/P;therealrentalprice,R/P;andtherealinterestrate,r.Theneutralityofmoneyapply,asanapproximation,totheentirepathofmoneygrowth.46.InflationintheEquilibriumBusiness-CycleModelMoneyGrowth,Inflation,andtheNominalInterestRateAnalyzehowthetimepathofthenominalquantityofmoney,Mt,determinesthetimepathofthepricelevel,Pt,and,hence,theinflationrate,πt.WealsoassumefornowthatYt

andrt

areconstantovertime.47.InflationintheEquilibriumBusiness-CycleModelMoneyGrowth,Inflation,andtheNominalInterestRate∆Mt

=Mt+1−Mtµt

=∆Mt/MtMt+1=(1+µt)·Mtπt

=∆Pt/Ptπt=(Pt+1−Pt)/PtPt+1=(1+πt)·Pt48.InflationintheEquilibriumBusiness-CycleModelMoneyGrowth,Inflation,andtheNominalInterestRateShowthatWhenMtgrowssteadilyattherateµ,thepricelevel,Pt,willalsogrowsteadilyattherateµ.π=µ49.InflationintheEquilibriumBusiness-CycleModelMoneyGrowth,Inflation,andtheNominalInterestRateTherealquantityofmoneydemanded,L(Y,i),doesnotvaryovertime.realGDP,Y,isfixed.i=r+πi=r+µSinceweassumedthatrandµarefixed,iisunchanging.SinceYandiarefixed,wehaveverifiedthattherealquantityofmoneydemanded,L(Y,i),isunchanging.50.InflationintheEquilibriumBusiness-CycleModelMoneyGrowth,Inflation,andtheNominalInterestRateThelevelofrealmoneydemanded,L(Y,i),equalstheunchanginglevelofrealmoneybalances,Mt/Pt

.L(Y,i)andMt/Pt

arebothfixedovertime.Therefore,ifthelevelsofthetwovariablesareequalinthecurrentyear,year1,theywillremainequalineveryfutureyear.51.InflationintheEquilibriumBusiness-CycleModelMoneyGrowth,Inflation,andtheNominalInterestRateDeterminationofpricelevel:P1=M1/L(Y,i)πt,istheconstantπ=µ.52.InflationintheEquilibriumBusiness-CycleModelMoneyGrowth,Inflation,andtheNominalInterestRateTheinflationrate,π,equalstheunchanginggrowthrateofmoney,µ.Realmoneybalances,Mt/Pt,arefixedovertime.Thenominalinterestrate,i,equalsr+µ,whereristheunchangingrealinterestrate.53.InflationintheEquilibriumBusiness-CycleModelMoneyGrowth,Inflation,andtheNominalInterestRateTherealquantityofmoneydemanded,L(Y,i),isfixedovertime,whereYistheunchangingrealGDP.P1=M1/L(Y,i)54.InflationintheEquilibriumBusiness-CycleModelATrendintheRealDemandforMoneyAssumethatL(Y,i)growssteadilyattheconstantrateγ.Thisgrowthmightreflectlong-termgrowthofrealGDP55.InflationintheEquilibriumBusiness-CycleModelATrendintheRealDemandforMoneyRealmoneybalances,Mt/Pt,increasebecauseofgrowthinthenumerator,Mt,attherateµ,butdecreasebecauseofgrowthinthedenominator,Pt,attherateπ.growthrateofMt/Pt

=µ−π56.InflationintheEquilibriumBusiness-CycleModelATrendintheRealDemandforMoneyIfL(Y,i)growsatrateγ,Mt/Ptmustalsogrowatrateγ.γ=µ−ππ=µ−γ57.InflationintheEquilibriumBusiness-CycleModel58.