宏观经济学课后习题英文版

第1章导论

二、概念题

答：在解释产出和价格是如何决定时，通常可以用AS-AD模型解决，但是必须首先明确所考虑的

时间是怎样的。

垂直的AS曲线描述的是长期的情况，产出只由供给曲线决定而价格是由需求和供给水平共同决定

的。水平的AS曲线描述的是短期的情形，此时产出由总需求决定，价格是固定不变的。向上倾斜的AS

曲线描述的是中期情形，总供给和总需求的波动会影响生产能力和价格水平既定不变条件下的实际产

量。

AD-AS模型是对现实世界的非常简单的陈述，它无法描述所有居民和经济中的企业行为。在这个框

架中，总需求变动对产量和价格的影响在很大程度上取决于A5曲线的斜率。应该记住，当潜在产出能

力提升时，长期A$曲线会逐年向右移动，因此，即使在AD曲线固定不变时，价格水平会随着时间的推

移而下降。

三、技术题

答：产出缺口被定义为实际GDP和潜在GDP的差额。因此在该假设的经济中产出缺口为360亿美元

(=1560-1200).预计失业水平比正常水平高。

第2章国民收入核算

二、概念题

1.Governmenttransferpayments(TR)donotariseoutofanyproductionactivityandarethusnot

countedinthevalueofGDP.Ifthegovernmenthiredthepeoplewhocurrentlyreceivetransfer

payments,thentheirwageswouldbecountedaspartofgovernmentpurchases(G),whichiscounted

inGDP.ThereforeGDPwouldrise.

2.a.Ifthefirmbuysacarforanexecutive'suse,thepurchasecountsasinvestment(I).Butifthefirm

paystheexecutiveahighersalaryandshethenbuysacar,thepurchaseiscountedasconsumption

(C).

2.b.TheservicesthatahomemakerprovidesarenotcountedinGDP(regardlessoftheirvalue).However,

ifanindividualofficiallyhireshisorherspousetoperformhouseholddutiesatacertainwagerate,

thenthewagesearnedwillbecountedinGDPandGDPwillincrease.

2.c.IfyoubuyaGermancar,consumption(C)willincreasebutnetexports(NX=X-Q)willdecrease.

OverallGDPwillincreasebythevalueaddedattheforeigncardealership,sincetheimportpriceis

likelytobelessthanthesalesprice.IfyoubuyanAmericancar,consumptionandthusGDPwill

increase.(Note:Ifthecaryoubuycomesoutofthecardealer'sinventory,thentheincreaseinCwill

bepartiallyoffsetbeadeclineinI,andGDPwillagainonlyincreasebythevalueadded.)

3.GDPisthemarketvalueofallfinalgoodsandservicescurrentlyproducedwithinthecountry.(The

U.S.GDPincludesthevalueoftheHondasproducedbyaJapanese-ownedassemblyplantthatis

locatedintheU.S.,butitdoesnotincludethevalueofNikeshoesthatareproducedbyan

American-ownedshoefactorylocatedinMalaysia.)

GNPisthemarketvalueofallfinalgoodsandservicescurrentlyproducedusingassetsownedby

domesticresidents.(HerethevalueoftheHondasproducedbyaJapanese-ownedHondaplantisnot

countedbutthevalueoftheNikesbytheAmerican-ownedshoeplantis.)

Neitherisnecessarilyabettermeasureoftheoutputofanation.TheactualvalueoftheGDPand

GNPfortheU.S.isfairlyclose.

4.TheNDP(netdomesticproduct)isdefinedasGDPminusdepreciation.Depreciationmeasuresthe

valueofthecapitalthatwearsoutduringtheproductionprocessandhastobereplaced.Therefore

NDPcomesclosertomeasuringthenetamountofgoodsproducedinthiscountry.Ifthisiswhatyou

wanttomeasure,thenNDPshouldbeused.

5.IncreasesinrealGDPdonotnecessarilymeanincreasesinwelfare.Forexample,ifthepopulation

ofacountryincreasesbymorethanrealGDP,thenthepopulationofthecountryisonaverageworse

off.Alsosomeincreasesinoutputcomefromwelfarereducingevents.Forexample,increased

pollutionmaycausemorelungcancer,andthetreatmentofthelungcancerwillcontributetoGDP.

Similarly,anincreaseincrimemayleadtoovertimeworkforpoliceofficers,whoseincreasedsalary

willincreaseGDP.Butthewelfareofthepeopleinthecountrymaynothaveincreasedineithercase.

Ontheotherhand,GDPdoesnotalwaysaccuratelymeasurequalityimprovementsingoodsor

services(fastercomputersorimprovedhealthcare)thatimprovepeople'swelfare.

6.TheCPI(consumerpriceindex)andthePPI(producerpriceindex)arebothmeasuredbylooking

atacertainmarketbasket.TheCPFsbasketcontainsmostlyfinishedgoodsandservicesthat

consumerstendtobuyregularlyintheirdailylives.ThePPFsbasketcontainsrawmaterialsand

semi-finishedgoods,thatis,itmeasurescoststotheproducerofaproductanditsfirstuser.TheCPI

isaconcurrenteconomicindicator,whereasthePPIisaleadingeconomicindicator.

7.TheGDP-deflatorisapriceindexthatcoverstheaveragepriceincreaseofallfinalgoodsand

servicescurrentlyproducedwithinaneconomy.ItisdefinedastheratioofcurrentnominalGDPto

currentrealGDP.NominalGDPismeasuredincurrentdollars,whilerealGDPismeasuredin

so-calledbase-yeardollars.EventhoughearlyestimatesoftheGDP-deflatortendtobeunreliable,the

GDP-deflatorcanbeamoreusefulpriceindexthantheCPIorPPI(bothofwhicharefixedmarket

baskets).Thisistruefortworeasons:firstitmeasuresamuchwidercross-sectionofgoodsand

services;second,afixedmarketbasketcannotaccountforpeoplesubstitutingawayfromgoods

whoserelativepriceshavechanged,whiletheGDP-deflator,whichincludesallgoodsandservices

producedwithinthecountry,can.

8.IfnominalGDPhassuddenlydoubled,itismostlikelyduetoanincreaseintheaveragepricelevel.

Therefore,thefirstthingyouwouldwanttocheckisbyhowmuchtheGDP-deflatorhaschanged,to

calculatebyhowmuchrealoutput(GDP)haschanged.IfnominalGDPandtheGDP-deflatorhave

bothdoubled,thenrealGDPshouldbethesame.

9.Assumetheloanyoumadeyieldsyouanannualnominalreturnof7%.Iftherateofinflationis4%,

thenyourrateofreturninrealtermsisonly3%.If,ontheotherhand,ifinflationrateis10%,then

youwillactuallygetanegativerealrateofreturn,thatis,youwilllose3%ofyourpurchasingpower.

Onewaytoprotectyourselfagainstsuchalossofpurchasingpoweristoadjusttheinterestratefor

inflation,thatis,toindextheloan.Inotherwords,youcanrequirethat,inadditiontothespecified

interestrateoftheloanof,let'ssay,3%,theborroweralsohastopayaninflationpremiumequalto

thepercentagechangeintheCPI.Inthiscase,arealrateofreturnof3%wouldbeguaranteed.

三、技术题

1.ThetextcalculatesthechangeinrealGDPin1992pricesinthefollowingway:

[RGDPoi-RGDP92]/RGDP92=[3.50・1.50]/l.50=1.33=133%.

TocalculatethechangeinrealGDPin2001prices,wefirsthavetocalculatetheGDPof1992in

2001prices.Thuswetakethequantitiesconsumedin1992andmultiplythembythepricesof2001,

asfollows:

Beer1at$2.00=$2.00

Skittles1at$0.75=$0.75

Total$2.75

ThechangeinrealGDPcannowbecalculatedas

[6.25-2.75]/2.75=1.27=127%.

WecanseethatthegrowthrateofrealGDPcalculatedthiswayisroughlythesameasthegrowth

ratecalculatedabove.

2.a.Therelationshipbetweenprivatedomesticsaving,investment,thebudgetdeficitandnetexportsis

shownbythefollowingidentity:

S-I=(G+TR-TA)+NX.

Therefore,ifweassumethattransferpayments(TR)remainconstant,thenanincreaseintaxes(TA)

hastobeoffseteitherbyanincreaseingovernmentpurchases(G),adecreaseinnetexports(NX),or

adecreaseinthedifferencebetweensaving(S)andinvestment(I).

2.b.FromtheequationYD=C+Sitfollowsthatanincreaseindisposableincome(YD)willbereflected

inanincreaseinconsumption(C),saving(S),orboth.

2.c.FromtheequationYD=C4-Sitfollowsthatwheneitherconsumption(C)orsaving(S)increases,

disposableincome(YD)mustincreaseaswell.

3.a.SincedepreciationD=Ig-In=800-200=600==>

NDP=GDP-D=6,000-600=5,400

3.b.FromGDP=C+I+G+NX==>NX=GDP-C-I-G==>

NX=6,000-4,000-800-1,100=100.

3.c.BS=TA-G-TR=>(TA-TR)=BS+G==>(TA-TR)=30+1,100=1,130

3.d.YD=Y-(TA-TR)=5,400-1,130=4,270

3.e.S=YD-C=4,270-4,000=270

4.a.S=YD-C=5,100-3,800=1,300

4.b.FromS-1=(G+TR-TA)+NX=>I=S-(G+TR-TA)-NX=1,30()-200-(-1()0)=1^00.

4.c.FromY=C+I+G+NX==>G=Y-C-1-NX==>

G=6,0(X)-3,800-1,200-(-100)=1,100.

Also:YD=Y-TA+TR=>TA-TR=Y-YD=6,000-5,100=>TA-TR=900

FromBS=TA-TR-G=>G=(TA-TR)-BS=9(X)-(-2(X))==>G=1,10()

5.AccordingtoEquation(2)inthetext,thevalueoftotaloutput(inbillionsofdollars)canbe

calculatedas:Y=laborpayments+capitalpayments+profits=$60+$20+$0=$80

6.a.SincenominalGDPisdefinedasthemarketvalueofallfinalgoodsandservicescurrentlyproduced

inthiscountry,wecanonlymeasurethevalueofthefinalproduct(bread),andthereforeweget$2

million(since1millionloavesaresoldat$2each).

6.b.AnalternativewayofmeasuringtotalGDPwouldbetocalculateallthevalueaddedateachstepof

production.Thetotalvalueoftheingredientsusedbythebakeriescanbecalculatedas:

1,200,000poundsofflour($1perpound)=1,200,000

100,000poundsofyeast($1perpound)=100,000

100,000poundsofsugar($1perpound)=100,000

100,000poundsofsalt($1perpound)=100,000

=1,500,000

Since$2,000,000worthofbreadissold,thetotalvalueaddedatthebakeriesis$500,000.

7.IftheCPIincreasesfrom2.1to2.3,therateofinflationcanbecalculatedinthefollowingway:

rateofinflation=(2.3-2.1)/2.1=0.095=9.5%

TheCPIoftenoverstatesinflation,sinceitiscalculatedbyusingafixedmarketbasketofgoodsand

services.ButthefixedweightsintheCPFsmarketbasketcannotcapturethetendencyofconsumers

tosubstituteawayfromgoodswhoserelativepriceshaveincreased.Therefore,theCPIwilloverstate

theincreaseinconsumers*expenditures.

8.Therealinterestrate(r)isdefinedasthenominalinterestrate(i)minustherateofinflation(兀).

Thereforethenominalinterestrateistherealinterestrateplustherateofinflation,or

i=r+7t=3%+4%=7%.

第三章增长与积累

二、概念题

1.Theproductionfunctionprovidesaquantitativelinkbetweeninputsandoutput.Forexample,the

Cobb-Douglasproductionfunctionmentionedinthetextisoftheform:

Y=F(N,K)=AN'-0Ke,

whereYrepresentsthelevelofoutput.(1-0)and0areweightsequaltothesharesoflabor(N)

andcapital(K)inproduction,whileAisoftenusedasameasurefortheleveloftechnology.Itcanbe

easilyshownthatlaborandcapitaleachcontributetoeconomicgrowthbyanamountthatisequalto

theirindividualgrowthratesmultipliedbytheirrespectiveshareinincome.

2.TheSolowmodelpredictsconvergence,thatis,countrieswiththesameproductionfunction,savings

rate,andpopulationgrowthwilleventuallyreachthesamelevelofincomepercapita.Inotherwords,

apoorcountrymayeventuallycatchuptoaricheronebysavingatthesamerateandmaking

technologicalinnovations.However,ifthesecountrieshavedifferentsavingsrates,theywillreach

differentlevelsofincomepercapita,eventhoughtheirlong-tenngrowthrateswillbethesame.

3.Aproductionfunctionthatomitsthestockofnaturalresourcescannotadequatelypredicttheimpact

ofasignificantchangeintheexistingstockofnaturalresourcesontheeconomicperformanceofa

country.Forexample,thediscoveryofnewoilreservesoranentirelynewresourcewouldhavea

significanteffectonthelevelofoutputthatcouldnotbepredictedbysuchaproductionfunction.

4.InterpretingtheSolowresidualpurelyastechnologicalprogresswouldignore,forexample,the

impactthathumancapitalhasonthelevelofoutput.Inotherwords,thisresidualnotonlycaptures

theeffectoftechnologicalprogressbutalsotheeffectofchangesinhumancapital(H)onthegrowth

rateofoutput.Toeliminatethisproblemwecanexplicitlyincludehumancapitalintheproduction

function,suchthat

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

Thenthegrowthrateofoutputcanbecalculatedas

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

5.Thesavingsfunctionsy=sf(k)assumesthataconstantfractionofoutputissaved.Theinvestment

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

constantcapital-laborratio(k).Asteady-stateequilibriumisreachedwhensavingisequaltothe

investmentrequirement,thatis,whensy=(n+d)k.Atthispointthecapital-laborratiok=K/Nisnot

changing,socapital(K),labor(N),andoutput(Y)allmustbegrowingatthesamerate,thatis,the

rateofpopulationgrowthn=(AN/N).

6.Inthelongrun,therateofpopulationgrowthn=(AN/N)determinesthegrowthrateofthe

steady-stateoutputpercapita.Intheshortrun,however,thesavingsrate,technologicalprogress,and

therateofdepreciationcanallaffectthegrowthrate.

7.LaborproductivityisdefinedasY/N,thatis,theratioofoutput(Y)tolaborinput(N).Asurgein

laborproductivitythereforeoccursifoutputgrowsatafasterratethanlaborinput.IntheU.S.we

haveexperiencedsuchasurgeinlaborproductivitysincethemid-1990sduetotheenormousgrowth

inGDP.Thissurgecanbeexplainedfromtheintroductionofnewtechnologiesandmoreefficient

useofexistingtechnologies.Manyclaimthattheincreasedinvestmentinanduseofcomputer

technologyhasstimulatedeconomicgrowth.Furthermore,increasedglobalcompetitionhasforced

manyfirmstocutcostsbyreorganizingproductionandeliminatingsomejobs.Thus,withlarge

increasesinoutputandaslowerrateofjobcreationweshouldexpectlaborproductivitytoincrease.

(Oneshouldalsonotethatahigher-skilledlaborforcealsocancontributetoanincreaseinlabor

productivity,sincethesamenumberofworkerscanproducemoreoutputifworkersaremorehighly

skilled.)

三、技术题

l.a.AccordingtoEquation(2),thegrowthofoutputisequaltothegrowthinlabortimesthelaborshare

plusthegrowthofcapitaltimesthecapitalshareplustherateoftechnicalprogress,thatis,

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

1-0istheshareoflabor(N)and0istheshareofcapital(K).Thusifweassumethattherateof

technologicalprogress(AA/A)iszero,thenoutputgrowsatanannualrateof3.6percent,since

AY/Y=(0.6)(2%)+(04)(6%)+0%=1.2%+2.4%=+3.6%,

l.b.Theso-called"Ruleof70"suggeststhatthelengthoftimeittakesforoutputtodoublecanbe

calculatedbydividing70bythegrowthrateofoutput.Since70/3.6=19.44,itwilltakejustunder20

yearsforoutputtodoubleatanannualgrowthrateof3.6%,

l.c.NowthatAA/A=2%,wecancalculateeconomicgrowthas

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

Thusitwilltake70/5.6=12.5yearsforoutputtodoubleatthisnewgrowthrateof5.6%.

2.a.AccordingtoEquation(2),thegrowthofoutputisequaltothegrowthinlabortimesthelaborshare

plusthegrowthofcapitaltimesthecapitalshareplusthegrowthrateoftotalfactorproductivity

(TFP),thatis,

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

1-0istheshareoflabor(N)and0istheshareofcapital(K).Inthisexample0=0.3;therefore,

ifoutputgrowsat3%andlaborandcapitalgrowat1%each,thenwecancalculatethechangeinTFP

inthefollowingway

3%=(03)(1%)+(0.7)(l%)+AA/A=>AA/A=3%-1%=2%,

thatis,thegrowthrateoftotalfactorproductivityis2%.

2.b.Ifbothlaborandthecapitalstockarefixedandoutputgrowsat3%,thenallthisgrowthhastobe

contributedtothegrowthinfactorproductivity,thatis,AA/A=3%.

3.a.IfthecapitalstockgrowsbyAK/K=10%,theeffectonoutputwouldbeanadditionalgrowthrateof

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

3.b.IflaborgrowsbyAN/N=10%,theeffectonoutputwouldbeanadditionalgrowthrateof

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

3.c.IfoutputgrowsatAY/Y=7%duetoanincreaseinlaborbyAN/N=10%,andthisincreaseinlabor

isentirelyduetopopulationgrowth,thenpercapitaincomewoulddecreaseandpeople'swelfare

woulddecrease,since

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

3.d.Ifthisincreaseinlaborisduetoaninfluxofwomenintothelaborforce,theoverallpopulationdoes

notincreaseandincomepercapitawouldincreasebyAy/y=7%.Thereforepeople'swelfarewould

increase.

4.Figure3-4showsoutputperheadasafunctionofthecapital-laborratio,thatis,y=f(k).The

savingsfunctionissy=sf(k),anditintersectsthestraight(n+d)k-line,representingtheinvestment

requirement.Atthisintersection,theeconomyisinasteady-stateequilibrium.Nowletusassumethat

theeconomyisinasteady-stateequilibriumbeforetheearthquakehits,thatis,thesteady-state

capital-laborratioiscurrentlyk\Assumefurther,forsimplicity,thattheearthquakedoesnotaffect

people'ssavingsbehavior.

Iftheearthquakedestroysonequarterofthecapitalstockbutlessthanonequarterofthelabor

force,thenthecapital-laborratiofallsfromk'tok】andper-capitaoutputfallsfromy*toy.Now

savingisgreaterthantheinvestmentrequirement,thatis,sy1>(d+n)k),andthecapitalstockandthe

levelofoutputpercapitawillgrowuntilthesteadystateatkisreachedagain.

However,iftheearthquakedestroysonequarterofthecapitalstockbutmorethanonequarterofthe

laborforce,thenthecapital-laborratioincreasesfromk*tok2.Savingnowwillbelessthanthe

investmentrequirementandthusthecapital-laborratioandthelevelofoutputpercapitawillfalluntil

thesteadystateatk“isreachedagain.

Ifexactlyonequarterofboththecapitalstockandthelaborstockaredestroyed,thenthesteady

stateismaintained,thatis,thecapital-laborratioandtheoutputpercapitadonotchange.

Iftheseverityoftheearthquakehasaneffectonpeoples*savingsbehavior,thenthesavingsfunction

sy=sf(k)willmoveeitherupordown,dependingonwhetherthesavingsrate(s)increases(ifpeople

savemore,somorecanbeinvestedinanefforttorebuild)ordecreases(ifpeoplesaveless,sincethey

decidethatlifeistooshortnottoliveitup).

0

k.k

5.a.Anincreaseinthepopulationgrowthrate(n)affectstheinvestmentrequirement,andthe(n+d)k-line

getssteeper.Asthepopulationgrows,moresavingmustbeusedtoequipnewworkerswiththesame

amountofcapitalthattheexistingworkersalreadyhave.Thereforeoutputpercapita(y)willdecrease

aswillthenewoptimalcapital-laborratio,whichisdeterminedbytheintersectionofthesy-curveand

the(A+d)k-line.Sinceper-capitaoutputwillfall,wewillhaveanegativegrowthrateintheshort

run.However,thesteady-stategrowthrateofoutputwillincreaseinthelongrun,sinceitwillbe

determinedbythenewandhigherrateofpopulationgrowth.

5.b.Startingfromaninitialsteady-stateequilibriumatalevelofper-capitaoutputy\theincreaseinthe

populationgrowthrate(n)willcausethecapital-laborratiotodeclinefromk,tokbOutputpercapita

willalsodecline,aprocessthatwillcontinueatadiminishingrateuntilanewsteady-statelevelis

reachedatyt.Thegrowthrateofoutputwillgraduallyadjusttothenewandhigherleveln1.

6.a.Assumetheproductionfunctionisoftheform

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

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

Nowassumethatthereisnotechnologicalprogress,thatis,AA/A=0,andthatcapitalandlabor

growatthesamerate,thatis,AK/K=AN/N=n.Ifwealsoassumethatallnaturalresourcesavailable

arefixed,suchthatAZ/Z=0,thentherateofoutputgrowthwillbe

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

Inotherwords,outputwillgrowataratelessthannsincea+b<1.Thereforeoutputperworkerwill

fall.

6.b.Ifthereistechnologicalprogress,thatis,AA/A>0,thenoutputwillgrowfasterthanbefore,namely

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

IfAA/A>c,thenoutputwillgrowataratelargerthann,inwhichcaseoutputperworkerwill

increase.

6.c.Ifthesupplyofnaturalresourcesisfixed,thenoutputcanonlygrowataratethatissmallerthanthe

rateofpopulationgrowthandweshouldexpectlimitstogrowthaswerunoutofnaturalresources.

However,iftherateoftechnologicalprogressissufficientlylarge,thenoutputcangrowatarate

fasterthanpopulation,evenifwehaveafixedsupplyofnaturalresources.

7.a.Iftheproductionfunctionisoftheform

Y=K,/2(AN),/2,

andAisnormalizedto1,thenwehave

Y=K,/2N1/2.

Inthiscasecapital'sandlabor'ssharesofincomeareboth50%.

7.b.ThisisaCobb-Douglasproductionfunction.

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

FromY=K,/2N,/2==>Y/N=K,/2N-,/2==>y=k,/2=>

sk,/2=(n+d)k==>k,/2=(n+d)/s=(0.07+0.03)/(.2)=1/2==>k,Z2=2=y==>k=4.

7,dAY/Y=AA/A+0.5*(AK/K)+0.5*(AN/N)=0.02

8.a.Iftechnologicalprogressoccurs,thenthelevelofoutputpercapitaforanygivencapital-laborratio

increases.Thefunctiony=f(k)increasestoy=g(k),andthusthesavingsfunctionincreasesfrom

sf(k)tosg(k).

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

sg(k)-curvewiththe(n+d)k-lineisatahigherlevelofk.Thenewsteady-stateequilibriumwillnow

beatahigherlevelofsavingandoutputpercapita,andatahighercapital-laborratio.

8.c.Afterthetechnologicalprogressoccurs,thelevelofsavingandinvestmentwillincreaseuntilanew

andhigheroptimalcapital-laborratioisreached.Theratioofinvestmenttocapitalwillalsoincrease

inthetransitionperiod,sincemorehastobeinvestedtoreachthehigheroptimalcapital-laborratio.

9.TheCobb-Douglasproductionfunctionisdefinedas

Y=F(N,K)=AN>°K°.

Themarginalproductoflaborcanthenbederivedas

MPN=(AY)/(AN)=(1-0)AN-0Ke=(1-9)ANl-0Ke/N==(1-0)(Y/N)

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

第5章总供给与总需求

二、概念题

1.Theaggregatesupplycurveshowsthequantityofrealtotaloutputthatfirmsarewillingto

supplyateachpricelevel.Theaggregatedemandcurveshowsallcombinationsofrealtotaloutput

andthepricelevelatwhichthegoodsandthemoneysectorsaresimultaneouslyinequilibrium.

AlongtheAD-curvenominalmoneysupplyisassumedtobeconstantandnofiscalpolicychange

takesplace.

2.Theclassicalaggregatesupplycurveisvertical,sincetheclassicalmodelassumesthat

nominalwagesadjustveryquicklytochangesinthepricelevel.Thisimpliesthatthelabor

marketisalwaysinequilibriumandoutputisalwaysatthefull-employmentlevel.Ifthe

AD-curveshiftstotheright,firmstrytoincreaseoutputbyhiringmoreworkers,whotheytryto

attractbyofferinghighernominalwages.Butsincewearealreadyatfullemployment,nomore

workerscanbehiredandfirmsmerelybidupnominalwages.Thenominalwageincreaseis

passedonintheformofhigherproductprices.Intheend,thelevelofwagesandpriceswillhave

increasedproportionally,whiletherealwagerateandthelevelsofemploymentandoutputwill

remainunchanged.

Ifthereisadecreaseindemand,thenfirmstrytolayoffworkers.Workers,inturn,arewilling

toacceptlowerwagestostayemployed.Lowerwagecostsenablefirmstolowertheirproductprices.

Intheend,nominalwagesandpriceswilldecreaseproportionallybuttherealwagerateandthelevel

ofemploymentandoutputwillremainthesame.

3.Thereisnosingletheoryoftheaggregatesupplycurve,whichshowstherelationship

betweenfirms'outputandthepricelevel.Anumberofcompetingexplanationsexistfbrthefact

thatfirmshaveatendencytoincreasetheiroutputlevelasthepricelevelincreases.The

Keynesianmodelofahorizontalaggregatesupplycurvesupposedlydescribestheveryshortrun

(overaperiodofafewmonthsorless),whiletheclassicalmodelofaverticalaggregatesupply

curveissupposedtoholdtrueforthelongrun(aperiodofmorethan10years).Themedium-run

aggregatesupplycurveismostusefulforperiodsofseveralquartersorafewyears.This

upward-slopingaggregatesupplycurveresultsfromthefactthatwageandpriceadjustmentsare

slowanduncoordinated.Chapter6offersseveralexplanationsforthefactthatlabormarketsdo

notadjustquickly.Theseincludetheimperfectinformationmarket-clearingmodel,theexistence

ofwagecontractsorcoordinationproblems,andthefactthatfirmspayefficiencywagesand

pricechangestendtobecostly.

4.TheKeynesianaggregatesupplycurveishorizontalsincethepricelevelisassumedtobefixed.Itis

mostappropriatefortheveryshortrun(aperiodofafewmonthsorless).Theclassicalaggregate

supplycurveisverticalandoutputisassumedtobefixedatitspotentiallevel.Itismostappropriate

forthelongrun(aperiodofmorethan10years)whenpricesareabletofullyadjusttoallshocks.

5.Theaggregatesupplyandaggregatedemandmodelusedinmacroeconomicsisnotverysimilarto

themarketdemandandmark