多恩布什宏观经济学第十版课后习题答案09.doc

多恩布什宏观经济学第十版课后习题答案09.doc

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CHAPTER9

INCOMEANDSPENDING

SolutionstotheProblemsintheTextbook:

ConceptualProblems:

1.IntheKeynesianmodel,thepricelevelisassumedtobefixed,thatis,theAS-curveishorizontalandthelevelofoutputisdeterminedsolelybyaggregatedemand.Theclassicalmodel,ontheotherhand,assumesthatpricesalwaysfullyadjusttomaintainafull-employmentlevelofoutput,thatis,theAS-curveisvertical.Sincethemodelofincomedeterminationinthischapterassumesthatthepricelevelisfixed,itisaKeynesianmodel.

2.Anautonomousvariable’svalueisdeterminedoutsideofagivenmodel.Inthischapterthefollowingcomponentsofaggregatedemandhavebeenspecifiedasbeingautonomous:

autonomousconsumption（C*）autonomousinvestment（Io）,governmentpurchases（Go）,lumpsumtaxes（TAo）,transferpayments（TRo）,andnetexports（NXo）.

3.Sinceitoftentakesalongtimeforpolicymakerstoagreeonaspecificfiscalpolicymeasure,itisquitepossiblethateconomicconditionsmaydrasticallychangebeforeafiscalpolicymeasureisimplemented.Inthesecircumstancesapolicymeasurecanactuallybedestabilizing.Maybetheeconomyhasalreadybeguntomoveoutofarecessionbeforepolicymakershaveagreedtoimplementataxcut.Ifthetaxcutisenactedatatimewhentheeconomyisalreadybeginningtoexperiencestronggrowth,inflationarypressurecanbecreated.

Whilesuchinternallagsareabsentwithautomaticstabilizers（incometaxes,unemploymentbenefits,welfare）,theseautomaticstabilizersarenotsufficienttoreplaceactivefiscalpolicywhentheeconomyentersadeeprecession.

4. Incometaxes,unemploymentbenefits,andthewelfaresystemareoftencalledautomaticstabilizerssincetheyautomaticallyreducetheamountbywhichoutputchangesasaresultofachangeinaggregatedemand.Thesestabilizersareapartoftheeconomicmechanismandthereforeworkwithoutanycase-by-casegovernmentintervention.Forexample,whenoutputdeclinesandunemploymentincreases,theremaybeanincreaseinthenumberofpeoplewhofallbelowthepovertyline.Ifwehadnowelfaresystemorunemploymentbenefits,thenconsumptionwoulddropsignificantly.Butsinceunemployedworkersgetunemploymentcompensationandpeoplelivinginpovertyareeligibleforwelfarepayments,consumptionwillnotdecreaseasmuch.Therefore,aggregatedemandmaynotbereducedbyasmuchasitwouldhavewithouttheseautomaticstabilizers.

5. Thefull-employmentbudgetsurplusisthebudgetsurplusthatwouldexistiftheeconomywereatthefull-employmentlevelofoutput,giventhecurrentspendingortaxstructure.Sincethesizeofthefull-employmentbudgetsurplusdoesnotdependonthepositioninthebusinesscycleandonlychangeswhenthegovernmentimplementsafiscalpolicychange,thefull-employmentbudgetsurpluscanbeusedasameasureoffiscalpolicy.Othernamesforthefull-employmentbudgetsurplusarethestructuralbudgetsurplus,thecyclicallyadjustedsurplus,thehigh-employmentsurplus,andthestandardizedemploymentsurplus.Thesenamesmaybepreferable,sincetheydonotsuggestthatthereisaspecificfull-employmentlevelofoutputthatwewereunabletomaintain.

TechnicalProblems:

1.a.AD=C+I=100+（0.8）Y+50=150+（0.8）Y

TheequilibriumconditionisY=AD==>

Y=150+（0.8）Y==>（0.2）Y=150==>Y=5*150=750.

1.b.SinceTA=TR=0,itfollowsthatS=YD-C=Y-C.Therefore

S=Y-[100+（0.8）Y]=-100+（0.2）Y==>S=-100+（0.2）750=-100+150=50.

1.c.IfthelevelofoutputisY=800,thenAD=150+（0.8）800=150+640=790.

ThereforetheamountofinvoluntaryinventoryaccumulationisUI=Y-AD=800-790=10.

1.d.AD'=C+I'=100+（0.8）Y+100=200+（0.8）Y

FromY=AD'==>Y=200+（0.8）Y==>（0.2）Y=200==>Y=5*200=1,000

Note:

Thisresultcanalsobeachievedbyusingthemultiplierformula:

DY=（multiplier）（DSp）=（multiplier）（DI）==>DY=5*50=250,

thatis,outputincreasesfromYo=750toY1=1,000.

1.e.From1.a.and1.d.wecanseethatthemultiplieris5.

1.f. Sp Y=Sp

AD1=200=（0.8）Y

ADo=150+（0.8）Y

200

150

0

7501,000 Y

2.a.Sincethempchasincreasedfrom0.8to0.9,thesizeofthemultiplierisnowlargerandweshouldthereforeexpectahigherequilibriumincomelevelthanin1.a.

AD=C+I=100+（0.9）Y+50=150+（0.9）Y==>

Y=AD==>Y=150+（0.9）Y==>（0.1）Y=150==>Y=10*150=1,500.

2.b.FromDY=（multiplier）（DI）=10*50=500==>Y1=Yo+DY=1,500+500=2,000.

2.c.Sincethesizeofthemultiplierh