宏观经济学国民增长积累

CHAPTER3GROWTHANDACCUMULATION增长和积累ChapterHighlight（本章提要）Economicgrowthisduetogrowthininputs,suchaslaborandcapitalandtoimprovementsintechnology.Capitalaccumulationthroughsavingandinvestment.经济增长归因于诸如资本和劳动的投入,以及技术的进步通过储蓄和投资的资本积累Fig3-1GDPPerCapitalforFourCountries,1820-1998Thelong-runlevelofoutputperpersondependspositivelyonthesavingsrateandnegativelyontherateofpopulationgrowth.人均产出的长期水平与储蓄率

成正向关系?与人口增长率成反向关系?Theneoclassicgrowthmodelsuggeststhatthestandardoflivinginpoorcountrieswilleventuallyconvergetothelevelinwealthycountries.新古典增长模型:穷国的生活水平将会与富国趋同.3-1growthaccounting

增长核算Theproductionfunctionprovidesaquantitativelinkbetweeninputsandoutputs.Y=A.F(K,N)投入和产出之间的数量联系

△Y/Y=[(1-θ)*△N/N]+(θ*△K/K)+△A/A△Y/Y=[(1-θ)*△N/N]+(θ*△K/K)+△A/A]

△Y/Y---outputgrowth产出增长率(1-θ)----laborshare劳动份额θ--------capitalshare资本份额△K/K---capitalgrowth资本增长率△A/A-technicalprogress技术进步

totalfactorproductivityThegrowthrateoftotalfactorproductivityistheamountbywhichoutputwouldincreaseasaresultofimprovementsinmethodsofproduction,withallinputsunchanged.全要素生产率Example:capitalshare---.25;laborforcegrows---1.2%laborshare-----.75;capitalstock-------3%totalfactorproductivity------grows1.5%△Y/Y=[(1-θ)*△N/N]+(θ*△K/K)+△A/A=(.75*1.2%)+(.25*3%)+1.5%=3.15%PerCapitaGDPistheratioofGDPtopopulation.Definey=Y/N,k=K/N(capital-laborratio)Then

△Y/Y=△y/y+△N/N,△K/K=△k/k+△N/N

△Y/Y-△N/N=θ*[△K/K-△N/N]+△A/A

△y/y=θ*△k/k+△A/APostwarannualgrowthrates

GDPPERCAPITACAPITALPERCAPITAUSAJAPANDIFFERENCEUSAJAPANDIFFERENCE1950-19732.428.015.592.487.945.461973-19921.383.031.652.896.053.161950-19921.945.733.792.667.094.433-2EmpiricalEstimatesofGrowthNobelPrizewinner----RobertSolowExaminedtheperiod1909-1949intheUnitedStates.Conclusion:over80%ofthegrowthinoutputperlaborhouroverthatperiodwasduetotechnicalprogress.诺贝尔经济学奖获得者----罗伯特.索洛主要的结论在这一时期,人时产出的增长80%源于技术进步DataAverageofAnnualGrowthofTotalGDP----2.9%Capitalaccumulation-------------------------.32%Increasesintheinputoflabor--------------1.09%technicalprogress---------------------------1.49%

Solowfound

TheimportantdeterminantsofGDPgrowtharetechnicalprogress,increasedlaborsupply,andcapitalaccumulation.国内生产总值增长的重要决定因素是:技术进步,不断增长的劳动力的供给和资本积累SolowfoundFactorsotherthancapitalandlaborarenaturalresourcesandhumancapitalNaturalresources:muchofthisNorwegiangrowthspurtwasduetothediscoveryanddevelopmentofmassiveoilreserves.有别于资本和劳动的其他增长因素是自然资源和人力资本自然资源(挪威的井喷式经济增长源于大规模油气田的发现与开发)人力资本与增长Humancapital:Y=A.F(K,H,N)Mankiw,Romer,Weilsuggeststhattheproductionfunctionisconsistentwithfactorsharesofone-thirdeachforphysicalcapital,rawlabor,andhumancapital.人力资本物质资本\粗劳动\人力资本三分天下Fig3-2(a)RelationshipofInvestmentRatiotoGDPFig3-2(b)Relationshipof

AverageYearsofSchoolingRatiotoGDP

3-3Growththeory:theneoclassicalmodel

增长理论:新古典模型twoperiods:thefirst(neoclassicalgrowththeory)------inthelate1950sandthe1960sthesecond(endogenousgrowththeory)-----inthelate1980sandearlyearly1990s新古典增长理论20世纪50年代末－－２０世纪60年代内生增长理论阶段，20世纪80年代末---20世纪90年代

theneoclassicalgrowththeorytheneoclassicalgrowththeoryfocusesoncapitalaccumulationanditslinktosavingdecisionandthelike.关注：资本积累，与之相关联的储蓄决策等等。Beginswithasimplifyingassumption:notechnicalprogress.简化的假设----没有技术进步Thesteady-stateequilibriumfortheeconomyisthecombinationofpercapitaGDPandpercapitacapitalwheretheeconomywillremainatrest,thatis△y=0,△k=0.经济稳定的均衡状态是人均国内生产总值与人均资本额的综合：△y=0,△k=0.Theproductionfunctioninpercapitatermsiswritteny=f(k)Ascapitalrises,outputsrises,butoutputsriseslessathighlevelsofcapitalthanatlowlevels.以人均资本为变量的生产函数y=f(k)随着资本量的上升，产出增加，但是在人均资本额较高处，增长率慢于人均资本额较低处。Fig3-3PerCapitalProductionFunction“diminishingmarginalproduct”isthekeyexplanationofwhytheeconomyreachesasteadystateratherthangrowingendlessly.边际产量递减----是为什么经济达到稳定状态，而不是永无休止的增长的关键。STEADYSTATE（稳定状态）k—(tomaintainagivenlevel)dependsonpopulationgrowth(n)andthedepreciationrate(d).Assume:n≡△N/NTheinvestmentrequired=(n+d)k要使人均资本保持给定的水平，取决于人口增长率和折旧率n≡人口增长率所需要的投资额=(n+d)k新古典增长理论的假设条件AssumenogovernmentsectorandnoforeigntradeorcapitalflowsAssumealsothesavingisaconstantfraction,s,ofincome.Percapitasaving---------sy假设没有政府部门、对外贸易或资本的流动假设储蓄率是一个常量s则人均储蓄为syInvestmentandsavingSinceincomeequalsproduction,sosy=(n+d)k△k=sy-(n+d)kthesteadystateisdefinedby△k=0sy*=sf(k*)=(n+d)k*Fig3-4SteadyStateOutputandInvestmentTHEGROWTHPROCESS

增长路径Atthatsteadystate,bothkandyareconstant.Withpercapitaincomeconstant,aggregateincomeisgrowingatthesamerateaspopulation,thatis,atraten.在稳定状态，k和y都是常量。由于人均收入保持不变，总收入以人口增长的速度增长，即n。Fig3-5IncreaseinSavingRateMovestotheSteadyStateItfollowsthatthesteady-stategrowthrateisnotaffectedbythesavingsrate.Thisisoneofthekeyresultsofneoclassicalgrowththeory.稳定的增长率不受储蓄率的影响这是新古典增长理论的一个重要结论。GROWTHWITHEXOGENOUSTECHNOLOGICALCHANGEFIG3-7ExogenousTechnologicalChangeRECAP总结First,thegrowthrateofoutputsinsteadystateisexogenous;inthiscaseitisequalton.Itisthereforeindependentofthesavingsrate,s.第一，产出的增长率是外生的；在这种情形下，它等于n。因此，它是独立于储蓄率s。Second,althoughanincreaseinthesavingsratedoesnotaffectthesteady-stategrowthrate,itdoesincreasethesteady-statelevelofincomebyincreasingthecapital-outputratio.第二，尽管储蓄率的增长不会影响稳定状态的增长率，但是，它会通过增加资本产出比率，提高稳定状态下的收入水平。Third,whenweallowforproductivitygrowth,wecanshowthatifthereisasteadystate,thesteady-stategrowthrateofoutputremainsexogenous.第三，允许生产率上升时，依然存在稳定状态。产出的稳定增长率依然是外生的。thesteady-staterateofgrowthofpercapitaincomeisdeterminedbytherateoftechnicalprogress.thesteady-stategrowthrateofaggregateoutputisthesumoftherateoftechnicalprogressandtherateofpopulationgrowth.稳定状态下的人均收入的增长由技术进步率决定，稳定状态下的总产出的增长是技术进步率和人口增长率的总和。Thefinalpredictionofneoclassicaltheoryisthatofconvergence:iftwocountrieshavethesamerateofpopulationgrowth,thesamesavingsrate,andaccesstothesameproductionfunction,hisframework,poorcountriesarepoorbecausetheyhavelesscapital,butiftheysaveatthesamerateasrichcountriesandhaveaccesstothesametechnology,theywilleventuallycatchup.新古典增长理论的最后预测是“收敛”如果两个国家有同样的人口增长率，同样的储蓄率，同样的生产函数，他们将会达到同样的收入水平在这个理论框架下，穷国之所以穷是因为资本较少，但是，如果他们和富国有相同的储蓄率并能得到相同的技术落后，它们最终可以赶上富国的水平。Further,ifcountrieshavedifferentsavingsrates,thenaccordingtothissimpleneoclassicaltheory,theywillreachdifferentlevelsofincomeinthesteadystate.Butiftheirratesoftechnicalprogressandpopulationgrowtharethesame.Theirsteady-stategrowthrateswillbethesame.进一步,如果国家之间有不同的储蓄率,那么根据这个模型,他们在稳定状态下将会达到不同的收入水平.但是,如果技术进步率和人口增长率是相同的,他们的稳定增长率将是相同的.讨论的问题中国近三十年的发展中，具有多大的作用？人口红利消失后，如何转变经济增长模式？demographic

dividendPopulationdividenddemographicbonusordemographicdebt

China'sone-childpolicybringstheultimatedemographicdividendbutprobablymakesthecountrythemostbubble-proneinmoderntimes.下载MP3

中国的计划生育政策带来了最大的人口红利,但可能会让中国成为当代最容易产生泡沫的国家。

/story/001029246PopulationDividendorPopulationProblem?下载MP3

是人口红利?还是人口问题?

8/P-rkyj.htmlDemographicBonusandDemographicDebt:QuantitativeDelimitation,EmpiricalObservationandTheoreticalThinking下载MP3

人口红利与人口负债:数量界定、经验观察与理论思