中級宏觀課后習(xí)題答案1-7

Chapter3課后習(xí)題答案

SolutionstotheProblemsintheTextbook

ConceptualProblems

1.Aproductionfunctionprovidesaquantitativelinkbetweeninputsand

output.Forexample,theCobb-Douglasproductionfunctionmentionedin

thetextisoftheform:

Y=F(N,K)=AN1-0K°.

Inthisfunction,Yrepresentsthelevelofoutput,1-0and0areweights

equaltothesharesoflabor(N)andcapital(K)inproduction,whileA

measuresallothercontributionstooutput,inparticularthatoftechnology.It

canbeshownthatlaborandcapitaleachcontributetoeconomicgrowthby

anamountthatisequaltotheirindividualgrowthratesmultipliedbytheir

respectivesharesinincome.

2.TheSolowgrowthmodelpredictsconvergence,thatis,countrieswiththe

sameproductionfunction,savingsrate,andpopulationgrowthwill

eventuallyreachthesamelevelofincomepercapita.Inotherwords,a

poorcountrymayeventuallycatchuptoaricheronebysavingatthesame

rateandmakinguseofthesametechnologicalinnovations.However,if

thesecountrieshavedifferentsavingsrates,theywillreachdifferentlevels

ofincomepercapita,eventhoughtheirlong-termeconomicgrowthrates

willbethesame.

3.Aproductionfunctionthatomitsthestockofnaturalresourcescannot

adequatelypredicttheimpactofasignificantchangeintheexistingstockof

naturalresourcesontheeconomicperformanceofacountry.Forexample,

thediscoveryofnewoilreservesoranentirelynewresourcewouldhavea

significantpositiveeffectonacountry'slevelofGDPthatcouldnotbe

predictedbysuchaproductionfunction.

4.InterpretingtheSolowresidualpurelyastechnologicalprogresswould

ignore,forexample,theimpactthathumancapitalhasonthelevelof

output.Inotherwords,thisresidualnotonlycapturestheeffectof

technologicalprogressbutalsotheeffectofchangesinhumancapital(H),

achievedthroughmoreeducationortraining,onthegrowthrateofoutput.

Toeliminatethisproblemwecanexplicitlyincludehumancapitalinthe

productionfunction,suchthat

Y=F(K,N,H)=ANaKbHcwitha+b+c=1.

Inthiscase,thegrowthrateofoutputcanbecalculatedas

AY/Y=AA/A+a(AN/N)+b(AK/K)+c(AH/H).

Clearly,herethemagnitudeofAA/Aisdifferentfromthatderivedfromthe

simpleSolowgrowthmodelusingtheproductionfunction

Y=F(K,N)=ANaKb.

5.Thesavingsfunctionsy=sf(k)assumesthataconstantfractionofoutputis

saved.Theinvestmentrequirement,thatis,the(n+d)k-line,representsthe

amountofinvestmentneededtomaintainaconstantcapital-laborratio(k).

Asteady-stateequilibriumisreachedwhensavingisequaltothe

investmentrequirement,thatis,whensy=(n+d)k.Atthispointthe

capital-laborratiok=K/Nisnotchanging,socapital(K),labor(N),and

output(Y)allmustbegrowingatthesamerate,thatis,therateof

populationgrowthn=(AN/N).

6.Inthelongrun,(andinabsenceoftechnologicalprogress)thegrowthrate

ofthesteady-stateoutputpercapitaisdeterminedonlytherateof

populationgrowthn=(AN/N).However,intheshortrun,thesavingsrate

andtherateofdepreciationalsocanaffecttheeconomicgrowthrateofa

nation,ascanaone-timetechnologicaladvance.

7.LaborproductivityisdefinedasY/N,thatis,theratioofoutput(Y)tolabor

input(N).Thisimpliesthatasurgeinlaborproductivityoccursifoutput

growsatafasterratethanlaborinput.TheU.S.experiencedsuchasurge

inlaborproductivityinthemidandlate1990sduetolargeincreasesin

GDP.Thiscanbeexplainedbytheintroductionofnewtechnologiesand

moreefficientuseofexistingtechnologies,forexampleincreased

investmentinanduseofcomputertechnology.Furthermore,increased

globalcompetitionhasforcedmanyfirmstocutcostsbyreorganizing

productionandeliminatingjobs.Therefore,withlargeincreasesinoutput

andaslowerrateofjobcreationweshouldexpectlaborproductivityto

increase.(Oneshouldnote,however,thatamorehighlyskilledlaborforce

alsocancontributetoanincreaseinlaborproductivity,sincehighlyskilled

workerscanproducemuchmoreoutputthanthesamenumberofless

skilledworkers.)

TechnicalProblems

1a.AccordingtoEquation(2),thegrowthofoutputisequaltothegrowthin

labortimeslabor'sshareofincomeplusthegrowthofcapitaltimescapital's

shareofincomeplustherateoftechnicalprogress,thatis,

AY/Y=(1-0)(AN/N)+0(AK/K)+AA/A,

wherel-0istheshareoflabor(N)and0istheshareofcapital(K).

Therefore,ifweassumethattherateoftechnologicalprogressiszero(AA/A=

0),outputgrowsatanannualrateof3.6percent,since

AY/Y=(0.6)(2%)+(0.4)(6%)+0%=1.2%+2.4%=+3.6%,

b.Theso-called"Ruleof70"suggeststhatthelengthoftimeittakesfor

outputtodoublecanbecalculatedbydividing70bythegrowthrateofoutput.

Since70/3.6=19.44,itwilltakejustunder20yearsforoutputtodoubleatan

annualgrowthrateof3.6%.

c.NowthatAA/A=2%,wecancalculateeconomicgrowthas

AY/Y=(0.6)(2%)+(0.4)(6%)+2%=1.2%+2.4%+2%=+5.6%.

Thusitwilltake70/5.6=12.5yearsforoutputtodoubleatthisnewgrowth

rateof5.6%.

2a.AccordingtoEquation(2),thegrowthofoutputisequaltothegrowthin

labortimestheshareoflaborplusthegrowthofcapitaltimestheshareof

capitalplusthegrowthrateoftotalfactorproductivity,thatis,

AY/Y=(1-0)(AN/N)+0(AK/K)+AA/A,

wherel-0istheshareoflabor(N)and0istheshareofcapital(K).Inthis

example0=0.3;therefore,ifoutputgrowsat3%andlaborandcapitalgrowat

1%each,wecancalculatethechangeintotalfactorproductivityinthe

followingway

3%=(0.7)(1%)+(0.3)(1%)+AA/A==>AA/A=3%-1%=2%,

thatis,thegrowthrateoftotalfactorproductivityis2%.

b.Ifbothlaborandthecapitalstockarefixed,thatis,AN/N=AK/K=0,

andoutputgrowsat3%,thenallthegrowthhastobeattributedtothegrowth

intotalfactorproductivity,thatis,AA/A=3%.

3a.IfthecapitalstockgrowsbyAK/K=10%,theeffectwillbeanadditional

growthrateinoutputof

AY/Y=(0.3)(10%)=3%.

b.IflaborgrowsbyAN/N=10%,theeffectwillbeanadditionalgrowthrate

inoutputof

AY/Y=(0.7)(10%)=7%.

c.IfoutputgrowsatAY/Y=7%duetoanincreaseinlaborbyAN/N=10%

andthisincreaseinlaborisentirelyduetopopulationgrowth,thenpercapita

incomewilldecrease.Therefore,people'swelfarewilldecrease.Wecan

calculatethechangeinpercapitaincomeasfollows:

Ay/y=AY/Y-AN/N=7%-10%=-3%.

d.Iftheincreaseinlaborisnotduetopopulationgrowthbutinsteaddueto

aninfluxofwomenintothelaborforce,thenincomepercapitawillincreaseby

Ay/y=7%.Thereforepeople'swelfare(oratleasttheirlivingstandard)will

increase.

4.Figure3-4showsoutputperheadasafunctionofthecapital-labor

ratio,thatis,y=f(k),thesavingsfunction,thatissy=sf(k),andtheinvestment

requirement,thatis,the(n+d)k-line.Attheintersectionofthesavingsfunction

withtheinvestmentrequirement,theeconomyisinasteady-stateequilibrium.

Nowletusassumeforsimplicitythattheearthquakedoesnotaffectpeoples'

savingsbehaviorandthattheeconomyisinasteady-stateequilibriumbefore

theearthquakehits,thatis,thecapital-laborratioiscurrentlyk.

Iftheearthquakedestroysonequarterofthecapitalstockbutlessthan

onequarterofthelaborforce,thenthecapital-laborratiowillfallfromk*toki

andper-capitaoutputwillfallfromy'toy〔.Nowsavingisgreaterthanthe

investmentrequirement,thatis,syi>(d+n)ki,andthecapitalstockandthe

levelofoutputpercapitawillgrowuntilthesteadystateatk,isreachedagain.

However,iftheearthquakedestroysonequarterofthecapitalstockbut

morethanonequarterofthelaborforce,thenthecapital-laborratiowill

increasefromk'tok2.Saving(andgrossinvestment)nowwillbelessthanthe

investmentrequirementandthusthecapital-laborratioandthelevelofoutput

percapitawillfalluntilthesteadystateatk,isreachedagain.

Ifexactlyonequarterofboththecapitalstockandthelaborstockare

destroyed,thenthesteadystatewillbemaintained,thatis,thecapital-labor

ratioandtheoutputpercapitawillnotchange.

Iftheseverityoftheearthquakehasaneffectonpeoples'savings

behavior,thesavingsfunctionsy=sf(k)willmoveeitherupordown,

dependingonwhetherthesavingsrate(s)increases(ifpeoplesavemore,so

morecanbeinvestedlaterinanefforttorebuild)ordecreases(ifpeoplesave

less,sincetheydecidethatlifeistooshortnottoliveitup).Butineithercase,

anewsteady-stateequilibriumwillbereached.

5a.Anincreaseinthepopulationgrowthrate(n)affectstheinvestment

requirement,thatis,asngetslarger,the(n+d)k-linegetssteeper.Asthe

populationgrows,moreneedstobesavedandinvestedtoequipnewworkers

withthesameamountofcapitalthatexistingworkersalreadyhave.Sincethe

populationwillnowbegrowingfasterthanoutput,incomepercapita(y)will

decreaseandanewoptimalcapital-laborratiowillbedeterminedbythe

intersectionofthesy-curveandthenew(ni+d)k-line.Sinceper-capitaoutput

willfall,wewillhaveanegativegrowthrateintheshortrun.However,the

steady-stategrowthrateofoutputwillincreaseinthelongrun,sinceitwillbe

determinedbythenewandhigherrateofpopulationgrowthrii>n0.

b.Startingfromaninitialsteady-stateequilibriumatalevelofper-capitaoutput

y0,theincreaseinthepopulationgrowthrate(n)willcausethecapital-labor

ratiotodeclinefromkotoh.Outputpercapitawillalsodecline,aprocessthat

willcontinueatadiminishingrateuntilanewsteady-statelevelisreachedatyi.

Thegrowthrateofoutputwillgraduallyadjusttothenewandhigherlevelrn.

X

6a.Assumetheproductionfunctionisoftheform

Y=F(K,N,Z)=AKaNbZc==>

AY/Y=AA/A+a(AK/K)+b(AN/N)+c(AZ/Z),witha+b+c=1.

Nowassumethatthereisnotechnologicalprogress(AA/A=0),and

thatcapitalandlaborgrowatthesamerate,thatis,AK/K=AN/N=n.Ifwe

alsoassumethatallavailablenaturalresourcesarefixed,suchthatAZ/Z=0,

thentherateofoutputgrowthwillbe

AY/Y=an+bn=(a+b)n.

Inotherwords,outputwillgrowataratelessthannsincea+b<1,andoutput

perworkerwillfall.

b.Iftechnologicalprogressoccurs(AA/A>0),outputwillgrowfasterthan

before,namely

AY/Y=AA/A+(a+b)n.

IfAA/A<cn,outputwillgrowatalowerratethann,inwhichcaseoutputper

workerwillstilldecrease.

IfAA/A=cn,outputwillgrowatthesamerateasn,inwhichcaseoutputper

workerwillremainthesame.

ButifAA/A>cn,outputwillgrowataratehigherthann,inwhichcaseoutput

perworkerwillincrease.

c.Ifthesupplyofnaturalresourcesisfixed,thenoutputcanonlygrowata

ratethatissmallerthantherateofpopulationgrowthandweshouldexpect

limitstogrowthaswerunoutofnaturalresources.Butiftherateof

technologicalprogressissufficientlylarge,thenoutputcangrowatarate

fasterthanpopulation,evenifwehaveafixedsupplyofnaturalresources.

7.a.IftheproductionfunctionisoftheformY=K1,2(AN)1/2,andAis

normalizedto1,wehaveY=K12N12.Inthiscase,capital'sandlabor'sshares

ofincomeareboth50%.

b.ThisisaCobb-Douglasproductionfunction.

c.Asteady-stateequilibriumisreachedwhensy=(n+d)k.

FromY=K12N1/2==>Y/N=K12N-1/2==>y=k12==>sk1/2=(n+

d)k

==>k"2=(n+d)/s=(0.07+0.03)/(.2)=1/2==>k1/2=2=y==>k=4.

d.Atthesteady-stateequilibrium,outputpercapitaremainsconstant,

sincetotaloutputgrowsatthesamerateasthepopulation(7%),aslongas

thereisnotechnologicalprogress,thatis,AA/A=0.Butiftotalfactor

productivitygrowsatAA/A=2%,thentotaloutputwillgrowfasterthan

population,thatis,at7%+2%=9%,sooutputpercapitawillgrowat2%.

8

Iftechnologicalprogressoccurs,thenthelevelofoutputpercapitaforany

givencapital-laborratioincreases.Thefunctiony=f(k)increasestoy=g(k),

andthereforethesavingsfunctionincreasesfromsf(k)tosg(k).

b.Sinceg(k)>f(k),itfollowsthatsg(k)>sf(k)foreachlevelofk.Therefore,

theintersectionofthesg(k)-curvewiththe(n+d)k-lineisatahigherlevelofk.

Thenewsteady-stateequilibriumwillnowbeatahigherlevelofsavingand

outputpercapita,andatahighercapital-laborratio.

c.Afterthetechnologicalprogressoccurs,thelevelofsavingand

investmentwillincreaseuntilanewandhigheroptimalcapital-laborratiois

reached.Theinvestmentratiowillincreaseinthetransitionperiod,sincemore

investmentwillberequiredtoreachthehigheroptimalcapital-laborratio.

9.TheCobb-Douglasproductionfunctionisdefinedas

Y=F(N,K)=AN1-0K°.

Themarginalproductoflaborcanthenbederivedas

1

MPN=(AY)/(AN)=(1-0)AN°K°=(1-0)AN'°K°/N==(1-0)(Y/N)

==>labor'sshareofincome=[MPN*N]/Y=[(1-0)(Y/N)](N/Y)=(1-

0).

10a.Theproductionfunctionisoftheform

Y=K1/2N1/2==>Y/N=(K/N)1/2==>y=k1/2.

Fromk=sy/(n+d)=sk1/2/(n+d)==>k1/2=s/(n+d)

==>y=s/(n+d)=(0.1)/(0.02+0.03)=2

==>k'=sy7(n+d)=(0.1)(2)/(0.02+0.03)=4.

b.Steady-stateconsumptionequalssteady-stateincomeminus

steady-statesaving(orinvestment),thatis,

c*=y-sy=f(k*)-(n+d)k*.

Thegolden-rulecapitalstockcorrespondstothehighestpermanently

sustainablelevelofconsumption.Steady-stateconsumptionismaximized

whenthemarginalincreaseincapitalproducesjustenoughextraoutputto

covertheincreasedinvestmentrequirement.

Fromc=k1/2-(n+d)k==>(Ac/Ak)=(1/2)k-1/2-(n+d)=0

==>k"?=2(n+d)=2(.02+.03)=.1==>k1=10==>k=100.

Sincek=4<100,wehavelesscapitalatthesteadystatethanthegolden

rulesuggests.

c.Fromk=sy/(n+d)=sk1/2/(n+d)==>s=k12(n+d)=10(0.05)=.5.

d.Ifwehavemorecapitalthanthegoldenrulesuggests,wearesavingtoo

muchanddonothavetheoptimalamountofconsumption.

EmpiricalProblems

TheaveragemonthlygrowthrateoftheU.S.populationovertheperiod

2000-2010was0.1percent.Overthesameperiod,totalemploymentin

educationalservicesgrewonaverageby0.2percenteachmonth.This

impliesthattherearemoreteachersperstudentattheendofthisten-year

period.Everythingelsebeingconstant,onecouldinferthatsinceclass

sizewassmaller,studentsgotmoreattentionandthuslearnedmoreand

thatthereforetheaveragequalityofU.S.workersimproved.Ifthisis

true,thentheprospectsforfutureeconomicgrowthintheU.S.have

improved.

Thegraphbelowpresentsthechangeinemploymentintheinformation

technologyindustry.Theincreaseinemploymentinthatindustryinthe

1990scanprobablybeexplainedbytheincreaseinon-linebusinessor

otherInternetactivityandincreasedbusinessinvestmentincomputer

technology.But,tosomedegree,itmayalsobearesultofthelong

economicupswingthatoccurredduringthe1990s.

Aswecanseefromthegraphbelow,employmentintheinformation

technologyindustrydecreasedsharplyagainafter2000,whichismost

likelyduetothefactthatmanybusinessesfeltthattheyhadalready

investedsufficientlyinnewcomputertechnology.Assoftwarebecame

easiertouseandpeoplebecamemorecomputersavvy,therewasalso

lessneedt。hireITpersonnel.

AllEmployees:InformationServices(USINFO)

Source:U.S.DepartmentofLabor:BureauofLaborStatistics

19952000200520102015

ShadedareasindicateUSrecessions.

2010

Chapter5課后習(xí)題答案

SolutionstotheProblemsintheTextbook

ConceptualProblems

1.Theaggregatesupplycurveshowsthequantityoftotaloutputthat

firmsarewillingtosupplyateachpricelevel.Theaggregatedemandcurve

showstotaloutputdemanded.Itdepictsallcombinationsofrealtotaloutput

andthepricelevelatwhichthegoodsandmoneysectorsaresimultaneously

inequilibrium.AlongtheAD-curve,nominalmoneysupplyisassumedtobe

constant.

2.Theclassicalaggregatesupplycurveisvertical,sincetheclassicalmodel

assumesthatnominalwagesalwaysadjustimmediatelytochangesinthe

pricelevel.Thisimpliesthatthelabormarketisalwaysinequilibriumand

outputisalwaysatthefull-employmentlevel.IftheAD-curveshiftstotheright,

firmstrytoincreaseoutputbyhiringmoreworkers,andtheytrytoattractthem

byofferinghighernominalwages.However,sincewearealreadyatfull

employment,theoverallworkforcedoesnotincrease,sofirmsmerelybidup

nominalwages.Thenominalwageincreaseispassedonintheformofhigher

productprices.Sincethelevelofwagesandpriceswillhaveincreased

proportionally,therealwagerateandthelevelsofemploymentandoutputwill

remainunchanged.

Ifthereisadecreaseindemand,workersarewillingtoacceptlowernominal

wagestostayemployed.Lowerwagecostsenablefirmstolowertheirprices,

andultimatelynominalwagesandpricesdecreaseproportionallywhilethereal

wagerateandthelevelsofemploymentandoutputremainthesame.

3.Theaggregatesupplycurveshowstherelationshipbetweenthetotal

outputthatfirmsarewillingtosupplyandtheaveragepricelevelinan

economy.Therearevarioustheoriesofhowthiscurveshouldbederived.

Competingexplanationsexistforthefactthatfirmshaveatendencyto

increasetheiroutputlevelasthepricelevelincreases.TheKeynesianmodel

ofahorizontalaggregatesupplycurvesupposedlydescribestheveryshortrun

(overaperiodofafewmonthsorless),whiletheclassicalmodelofavertical

aggregatesupplycurveissupposedtoholdtrueforthelongrun(aperiodof

morethan10years).Themedium-runaggregatesupplycurveismostuseful

forperiodsofseveralquartersorafewyears.Thisupward-slopingaggregate

supplycurveresultsfromthefactthatwageandpriceadjustmentsareslow

anduncoordinated.Chapter6offersseveralexplanationsforthefactthatlabor

marketsdonotadjustveryquickly.Theseincludetheimperfectinformation

market-clearingmodel,theexistenceofwagecontractsorcoordination

problems,andthefactsthatfirmspayefficiencywagesandpricechangestend

tobecostly.

4.TheKeynesianaggregatesupplycurveishorizontalsincethepricelevelis

assumedtobefixed.Itismostappropriatefortheveryshortrun(aperiodofa

fewmonthsorless).Theclassicalaggregatesupplycurveisverticaland

outputisassumedtobefixedatitspotentiallevel.Itismostappropriateforthe

longrun(aperiodofmorethan10years)whenpricesareabletofullyadjustto

allshocks.Neitherofthesetwoaggregatesupplycurvesdescribesavery

realisticorinterestingscenario.Themedium-runaggregatesupplycurveis

upward-slopingsincewageandpriceadjustmentsareassumedtobeslowand

uncoordinated.Thisscenarioismorerealisticandmostusefulforperiodsof

severalquartersorafewyears.

5.Theaggregatesupplyandaggregatedemandmodelusedin

macroeconomicsshouldnotbeconfusedwiththemarketdemandandmarket

supplymodelusedinmicroeconomics.Whiletheworkingsofbothmodels(the

distinctionbetweenshiftsofthecurvesversusmovementalongthecurves)

aresimilar,thesetwodistinctmodelsareunrelated.The"P"inthe

microeconomicmodelstandsfortherelativepriceofagood(ortheratioat

whichtwogoodsaretraded),whereasthe"P"inthemacroeconomicmodel

standsfortheaveragepricelevelofallgoodsandservicesproducedinthis

country,measuredinmoneyterms.

TechnicalProblems

1a.AsFigure5-11shows,adecreaseinincometaxesshiftsboththe

AD-curveandtheAS-curvetotheright.TheshiftintheAD-curvetendstobe

fairlylargeand,intheveryshortrun(whenpricesarefixed),leadstoa

significantincreaseinoutputwithoutachangeinprices.Butinthelongrun,

theAS-curvewillalsoshifttotheright.Sincelowerincometaxratesprovidean

incentivetoworkmore,outputwillincrease,butonlybyafairlysmallamount.

Thereforeweseealargeincreaseinthepricelevelwithaslightlyhigherlevel

ofrealGDPinthelongrun.

b.Supply-sideeconomicsincludesanypolicymeasurethatwillincrease

potentialGDPbyshiftingthelong-run(vertical)AS-curvetotheright.

Supply-sideeconomistsputforththeviewthatacutinincometaxrateswill

increasetheincentivetowork,save,andinvest.Someeconomistsclaimed

thatthiswouldincreaseaggregatesupplysomuchthattheinflationand

unemploymentrateswouldsimultaneouslydecrease,andthattheresulting

higheconomicgrowthmightevenleadtoanincreaseintaxrevenues,despite

lowertaxrates.However,whenthesepolicieswereimplementedintheearly

1980s,theydidnothavethepredictedeffects.AsseeninFigure5-11,the

long-runeffectofataxcutonoutputissmall,butthepricelevelmayincrease

substantially.

2a.

Accordingtothebalancedbudgettheorem,asimultaneousandequalincrease

ingovernmentpurchasesandtaxeswillshifttheAD-curvetotheright,asthe

positiveimpactoftheincreaseingovernmentspendingisgreaterthanthe

negativeimpactofthetaxincrease.ButiftheAS-curveisupwardsloping,then

thebalancedbudgetmultiplierwillbelessthanone,thatis,theincreasein

outputwillbelessthantheincreaseingovernmentpurchases.Thisoccurs

becausepartofthefiscalexpansionwillbecrowdedout,thatis,thelevelof

privatespendingwilldecrease,duetoahigherpricelevel,lowerrealmoney

balances,andtheresultingriseininterestrates.

b.IntheKeynesiancase,theAS-curveishorizontalandthepricelevel

remainsunchanged.Thereisnorealbalanceeffectandthereforeincome

increasesmorethanin2.a.,thatis,outputincreasesbythewholeshiftinthe

AD-curve.However,theinterestratestillincreasesandthereforethebalanced

budgetmultiplierislessthanone(butgreaterthanin2.a.).

c.Intheclassicalcase,theAS-curveisverticalandtheoutputlevel

remainsunchanged.Inthiscase,ashiftintheAD-curveleadstoa

priceincreaseandrealmoneybalancesdecline.Thereforeinterest

ratesincreasefurtherthanin2.b.oreven2.a.,leadingtofullcrowding

outofinvestment.Hencethebalancedbudgetmultiplieriszerointhe

classicalcase.

EmpiricalProblems

1.Asthegraphillustrates,otherdateswhenoilshocksmighthavetaken

placeinclude1979-1981,1990-1991,1999-2002and2004-2009.

ConsumerPriceIndexforAllUrbanConsumers:Energy(CPIENGNS)

Source:U.S.DepartmentofLabor:BureauofLaborStatistics

(

0

0

L

B

A

B

6

I

X

U

P

U

I

)

0

191960197019801990200020102020

ShadedareasindicateUSrecessions.

2010

2.Asthescatterplotbelowindicates,thereisnoclearrelationship

betweenthegrowthrateofpotentialGDPandtheannualinflationrate

intheGDPdeflator,thoughthelineofbestfitshowsthattheremightbe

averyweaknegativerelationship.

5

d5

c4.

l

o

一d4

o

d

o35

9

S

S3

M

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存25

2n------------1------------1------------1------------1------------

0246810

InflationinGDPdeflator

RunningtheregressioninEXCELonecanobtain:

potentialRGDPgrowth=3.6-0.04*inflationintheGDPdeflator

Thecoefficientontheinflationrateisstatisticallynotsignificantlydifferent

fromzero(sincethet-statisticsisonlyequalto-1.29),Thus,onecan

concludethat,onaverage,theinflationratehasnosignificantimpacton

thegrowthofpotentialoutput.

Chapter6課后習(xí)題答案

SolutionstotheProblemsintheTextbook

ConceptualProblems

1.TheaggregatesupplycurveandthePhillipscurvedescribeverysimilar

relationshipsandbothcurvescanbeusedtoanalyzethesamephenomena.

TheAS-curveshowsarelationshipbetweenthepricelevelandthelevelof

output,whilethePhillipscurveshowsarelationshipbetweentheinflation

andunemploymentrates.Forexample,amovementalongthe

upward-slopingAS-curvedepictsanincreaseinthepricelevelthatis

associatedwithanincreaseinthelevelofoutput.ButOkun'slawstatesthat

changesinoutputandtherateofunemploymentaretightlylinked.Therefore,

withanincreaseinthepricelevel(ahigherlevelofinflation)therewillbea

higherlevelofoutput(alowerlevelofunemployment).ThustheAS-curveis

upwardslopingwhilethePhillipscurveisdownward-sloping.This

downward-slopingPhillipscurveshiftswheneverinflationaryexpectations

change.Ifoneassumesthatworkerswillchangetheirwagedemands

whenevertheirinflationaryexpectationschange,onecanconcludethata

shiftinthePhillipscurvecorrespondstoashiftintheupward-sloping

AS-curve,sincehigherwagesimplyahighercostofproduction.

ThesimpleAD-ASdiagramdepictsastaticframework,whichrelat