宏经总结.docx
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宏经总结
....................................名词解释
Multiplierthemultiplieristheamountbywhichequilibriumoutputchangeswhenautonomousaggregatedemandincreasesby1unit.
乘数：
外生变量每增加1美元引起的内生变量的增量。
Liquiditytrapasituationinwhichthepublicisprepared,atagiveninterestrate.toholdwhateveramountofmoneyissupplied.
流动性陷阱：
由于货币需求的极端利率弹性而形成的水平的LM曲线
Perfectcapitalmobilitycapitalisperfectlymobileinternationallywheninvestorscanpurchaseassetsinanycountrytheychoosequickly,withlowtransactioncostsandinunlimitedamounts.
资本完全流动性：
在资本完全流动的时候，资本有能力以最小的交易成本，在寻求最高收益过程中的跨国界立即流动。
IScurvetheiscurveshowscombinationsofinterestratesandlevelsofoutputsuchthatplannedspendingequalsincome.
IS曲线：
实际利率和收入水平的所有结合点的几何表示，该线上计划支出等于收入。
LMcurvetheLMcurveshowscombinationsofinterestratesandlevelsofoutputsuchthatmoneydemandequalsmoneysupply.
LM曲线：
实际利率和收入水平的所有结合点的几何表示，该线上货币需求等于货币供给。
GDPisthevalueofallfinalgoodsandservicesproducedinthecountrywithinagivenperiod.
GDP：
一年内，对一个国家范围内所产生的全部商品和服务的衡量。
CPImeasuresthecostofbuyingafixedbasketofgoodsandservicesrepresentativeofthepurchasesofurbanconsumers.
GDPdeflatoristheratioofnominalGDPinagivenyeartorealGDPofthatyear.
GDP缩减指数：
名义GDP被实际GDP除后的结果，它是对价格水平的衡量。
Aggregatesupplycurve（总供给曲线）describes,foreachgivenpricelevel,thequantityoutputfirmsarewillingtosupply.
Theaggregatedemandcurve（总需求曲线）showsthecombinationsofthepricelevelandlevelofoutputatwhichthegoodsandmoneymarketsaresimultaneouslyinequilibrium.
Fiscalpolicy（财政政策）isthepolicyofthegovernmentwithregardtothelevelofgovernmentpurchases,theleveloftransfersandthetaxstructure.
Monetarypolicy（货币政策）isaccommodatingwhen,inthecourseofafiscalexpansion,themoneysupplyisincreasedinordertopreventinterestratesfromincreasing.
Crowdingout（挤出）occurswhenexpansionaryfiscalpolicycausesinterestratestorise,therebyreducingprivatespendingparticularlyinvestment.
∙Iftheinterestsensitivityofinvestment（b）goesup,thenwehavemorecrowdingout.
∙Iftheinterestsensitivityofmoneydemand（h）goesup,thenwehavelesscrowdingout.
∙Iftheincomeelasticityofmoneydemand（k）goesup,thenwehavemorecrowdingout.
∙Ifthemultiplier（）goesup,thenwehavemorecrowdingout.
问答题：
1.a.AccordingtoEquation
（2）,thegrowthofoutputisequaltothegrowthinlabortimesthelaborshareplusthegrowthofcapitaltimesthecapitalshareplustherateoftechnicalprogress,thatis,
Y/Y=（1-）（N/N）+（K/K）+A/A,where
1-istheshareoflabor（N）andistheshareofcapital（K）.Thusifweassumethattherateoftechnologicalprogress（A/A）iszero,thenoutputgrowsatanannualrateof3.6percent,since
Y/Y=（0.6）（2%）+（0.4）（6%）+0%=1.2%+2.4%=+3.6%,
.b.Theso-called"Ruleof70"suggeststhatthelengthoftimeittakesforoutputtodoublecanbecalculatedbydividing70bythegrowthrateofoutput.Since70/3.6=19.44,itwilltakejustunder20yearsforoutputtodoubleatanannualgrowthrateof3.6%,
.c.NowthatA/A=2%,wecancalculateeconomicgrowthas
Y/Y=（0.6）（2%）+（0.4）（6%）+2%=1.2%+2.4%+2%=+5.6%.
Thusitwilltake70/5.6=12.5yearsforoutputtodoubleatthisnewgrowthrateof5.6%.
应用题：
ExpenditureSectorMoneySector
Sp=C+I+G+NXM=700
C=100+（4/5）YDP=2
YD=Y-TAmd=（1/3）Y+200-10i
TA=（1/4）Y
I=300-20i
G=120
NX=-20
（a）Derivetheequilibriumvaluesofconsumption（C）andmoneydemand（md）.
（b）Howmuchofinvestment（I）willbecrowdedoutifthegovernmentincreasesitspurchasesbyG=160andnominalmoneysupply（M）remainsunchanged?
（c）Byhowmuchwilltheequilibriumlevelofincome（Y）andtheinterestrate（i）change,ifnominalmoneysupplyisalsoincreasedtoM'=1,100?
答a.Sp=100+（4/5）[Y-（1/4）Y]+300-20i+120-20=500+（4/5）（3/4）Y–20i=500+（3/5）Y-20i
FromY=Sp==>Y=500+（3/5）Y-20i==>（2/5）Y=500-20i
==>Y=（2.5）（500-20i）==>Y=1,250-50iIS-curve
FromM/P=md==>700/2=（1/3）Y+200-10i==>（1/3）Y=150+10i
==>Y=3（150+10i）==>Y=450+30iLM-curve
IS=LM==>1,250-50i=450+30i==>800=80i==>i=10
==>Y=1,250-50*10==>Y=750
C=100+（4/5）（3/4）750=100+（3/5）750==>C=550
ms=M/P=700/2=350=md
Check:
md=（1/3）750+200-10*10=350
i
25ISoLMo
10
0
4507501,250Y
b.IS=（2.5）160=400==>IS'=1,650-50i
IS'=LM==>1,650-50i=450+30i==>1,200=80i==>i=15
==>Y=1,650-50*15==>Y=900
Sincei=+5==>I=-20*5==>I=-100
Check:
Sp=G+I=160–100=60==>Y=1（Sp）=2.5*60=150
深刻理解这段：
总收入的变化等于乘数乘以投资与政府购买的变化之和
iIS1
33
25LM
15
10
0
4507509001,2501,650Y
c.FromM'/P=md==>1,100/2=（1/3）Y+200-20i
==>（1/3）Y=350-20i==>Y=3（350-20i）==>Y=1,050+30i
IS1=LM1==>1,650-50i=1,050+30i==>600=80i==>i=7.5
==>Y=1,650-50（7.5）=1,275.
==>i=-7.5andY=375ascomparedto（b）.
i
25IS1LMo
LM
10
7.5
0
4509001,0501,2751,650Y
问答题：
1.IfthegovernmentwantstochangethecompositionofGDPtowardsinvestmentandawayfromconsumptionwithoutchangingthelevelofaggregatedemand,itneedstoimplementacombinationofrestrictivefiscalpolicyandexpansionarymonetarypolicy.Anincreaseinpersonalincometaxesoradecreaseintransferpaymentswillreduceconsumptionandthusaggregatedemand.TheIS-curvewillshifttotheleft,leadingtoadecreaseinthelevelofoutputandtheinterestrate.Toincreaseoutputtoitsoriginallevel,theFedcanundertakeexpansionarymonetarypolicy.ThiswillshifttheLM-curvetotheright,leadingtoafurtherdecreaseintheinterestrate,thusstimulatinginvestment,and,inturn,aggregatedemand.IftheintersectionofthenewIS-andLM-curvesisatthesameincomelevelaspreviously,thenthedecreaseintheinterestratewillhavestimulatedinvestmentspendingsufficientlytoexactlyoffsetthedecreaseinconsumption.（Note:
Thetaxincreasecanbecombinedwithaninvestmentsubsidy.Inthiscase,theIS-curvewillnotshiftasfartotheleftasbefore.）
Thefollowingdiagramshowstheeffectofadecreaseintransferpayments（TR）thatiscombinedwithanincreaseinmoneysupply（M/P）.Theadjustmentprocessisasfollows:
1-->2:
TR==>C==>Y==md==>i==>I==>Y.Effect:
Yandi.
2-->3:
（M/P）up==>i==>I==>Y==>md==>iEffect:
Yandi.
Combinedeffect:
Yaboutthesameandi.
iIS1LM1
IS2LM2
1
i1
2
i2
3
i3
0
Y2Y1Y
a.Assumethegovernmentwantstoincreaseoutputwithoutchanginginterestrates.WhatkindofpolicymixwouldyourecommendandhowwouldyourpolicymixaffectthecompositionofGDP?
ExplainyouranswerandtheadjustmentprocessesthattakeplacewiththehelpofanIS-LMdiagram.
Acombinationofexpansionaryfiscalandmonetarypolicywillincreaseoutputwithoutaffectinginterestrates.ExpansionaryfiscalpolicywillshifttheIS-curvetotherightandincomeandinterestrateswillbothincrease.ExpansionarymonetarypolicywillshifttheLM-curvetotherightandinterestrateswilldecreasewhileincomeincreases.Thuswewillhaveanincreaseinincomewithoutachangeininterestrates.
Sinceincomewillincrease,consumptionwillalsoincrease,butsinceinterestrateswillnotchange,inducedinvestmentwillnotbeaffected（Note:
Inamoreadvancedmodel,anincreaseinsalesexpectationsmayactuallyincreasetheoverallinvestmentlevel.SeeChapter14）.ThereforethelevelofinvestmentasafractionofGDPwilldecrease,whileconsumptionandgovernmentpurchaseswillhaveagreatershare.（Amorebalancedgrowthcanbeachievedifinvestmentsubsidiesaregiven.）
1-->2:
Gup==>Yup==>moneydemandup==>iup==>Idown==>Yup
Effect:
Yupandiup
2-->3:
（M/P）up==>idown==>Iup==>Yup==>moneydemandup==>iup.
Effect:
idownandYupOveralleffect:
Yupandiconstant.
iIS2LM1
IS1LM2
2
i2
i113
0
Y1Y2Y3Y
b.Assumemoneydemandisveryinterestinelasticandinvestmentisveryinterestelastic.Explainhowthelevelofsavings（S）,moneydemand（md）andinvestment（I）wouldbeaffectedifthegovernmentincreasedwelfarespending.
Ifmoneydemandisveryinterestinelastic,theLMcurveisverysteep,andifinvestmentisveryinterestelastic,theIScurveisveryflat.WithasteepLMcurveandaflatIScurve,fiscalpolicyisnotveryeffective,sincemostofitiscrowdedout.Anincreaseingovernmenttransferpayments（TR）shiftstheIS-curvetotherightandincomeandtheinterestrateincrease.Sinceincomehasincreased,savinghasincreasedandsincetheinterestratehasincreased,investmenthasdecreased.Intheend,moneydemandcannotbeaffectedsincemoneysupplyhasnotchanged.Theincreaseinincomeincreasesmoneydemand,buttheincreaseintheinterestratebringsitbacktoitsoriginallevel,thatis,inequilibriumwithmoneysupply.Theadjustmentprocessthattakesplaceisasfollows:
TRYmdiIYEffect:
Yi
Sinceiincreasesalotalot,theeffectonIislarge,asistheoffsettingeffect（thecrowdingouteffect）onoutput（Y）.ThismeansthattheoveralleffectonYissmall.
iLM
i1
io
IS1
ISo
0
YoY1Y
c“Ifinvestmentisveryinterestinelastic,thenmostofanincometaxratecutwillbecrowdedout;thereforetheFedshould
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