宏觀經(jīng)濟(jì)學(xué)國(guó)民增長(zhǎng)積累

CHAPTER3GROWTHANDACCUMULATION增長(zhǎng)和積累ChapterHighlight（本章提要）Economicgrowthisduetogrowthininputs,suchaslaborandcapitalandtoimprovementsintechnology.Capitalaccumulationthroughsavingandinvestment.經(jīng)濟(jì)增長(zhǎng)歸因于諸如資本和勞動(dòng)的投入,以及技術(shù)的進(jìn)步通過儲(chǔ)蓄和投資的資本積累Fig3-1GDPPerCapitalforFourCountries,1820-1998Thelong-runlevelofoutputperpersondependspositivelyonthesavingsrateandnegativelyontherateofpopulationgrowth.人均產(chǎn)出的長(zhǎng)期水平與儲(chǔ)蓄率

成正向關(guān)系?與人口增長(zhǎng)率成反向關(guān)系?Theneoclassicgrowthmodelsuggeststhatthestandardoflivinginpoorcountrieswilleventuallyconvergetothelevelinwealthycountries.新古典增長(zhǎng)模型:窮國(guó)的生活水平將會(huì)與富國(guó)趨同.3-1growthaccounting

增長(zhǎng)核算Theproductionfunctionprovidesaquantitativelinkbetweeninputsandoutputs.Y=A.F(K,N)投入和產(chǎn)出之間的數(shù)量聯(lián)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產(chǎn)出增長(zhǎng)率(1-θ)----laborshare勞動(dòng)份額θ--------capitalshare資本份額△K/K---capitalgrowth資本增長(zhǎng)率△A/A-technicalprogress技術(shù)進(jìn)步

totalfactorproductivityThegrowthrateoftotalfactorproductivityistheamountbywhichoutputwouldincreaseasaresultofimprovementsinmethodsofproduction,withallinputsunchanged.全要素生產(chǎn)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.諾貝爾經(jīng)濟(jì)學(xué)獎(jiǎng)獲得者----羅伯特.索洛主要的結(jié)論在這一時(shí)期,人時(shí)產(chǎn)出的增長(zhǎng)80%源于技術(shù)進(jìn)步DataAverageofAnnualGrowthofTotalGDP----2.9%Capitalaccumulation-------------------------.32%Increasesintheinputoflabor--------------1.09%technicalprogress---------------------------1.49%

Solowfound

TheimportantdeterminantsofGDPgrowtharetechnicalprogress,increasedlaborsupply,andcapitalaccumulation.國(guó)內(nèi)生產(chǎn)總值增長(zhǎng)的重要決定因素是:技術(shù)進(jìn)步,不斷增長(zhǎng)的勞動(dòng)力的供給和資本積累SolowfoundFactorsotherthancapitalandlaborarenaturalresourcesandhumancapitalNaturalresources:muchofthisNorwegiangrowthspurtwasduetothediscoveryanddevelopmentofmassiveoilreserves.有別于資本和勞動(dòng)的其他增長(zhǎng)因素是自然資源和人力資本自然資源(挪威的井噴式經(jīng)濟(jì)增長(zhǎng)源于大規(guī)模油氣田的發(fā)現(xiàn)與開發(fā))人力資本與增長(zhǎng)Humancapital:Y=A.F(K,H,N)Mankiw,Romer,Weilsuggeststhattheproductionfunctionisconsistentwithfactorsharesofone-thirdeachforphysicalcapital,rawlabor,andhumancapital.人力資本物質(zhì)資本\粗勞動(dòng)\人力資本三分天下Fig3-2(a)RelationshipofInvestmentRatiotoGDPFig3-2(b)Relationshipof

AverageYearsofSchoolingRatiotoGDP

3-3Growththeory:theneoclassicalmodel

增長(zhǎng)理論:新古典模型twoperiods:thefirst(neoclassicalgrowththeory)------inthelate1950sandthe1960sthesecond(endogenousgrowththeory)-----inthelate1980sandearlyearly1990s新古典增長(zhǎng)理論20世紀(jì)50年代末－－２０世紀(jì)60年代內(nèi)生增長(zhǎng)理論階段，20世紀(jì)80年代末---20世紀(jì)90年代

theneoclassicalgrowththeorytheneoclassicalgrowththeoryfocusesoncapitalaccumulationanditslinktosavingdecisionandthelike.關(guān)注：資本積累，與之相關(guān)聯(lián)的儲(chǔ)蓄決策等等。Beginswithasimplifyingassumption:notechnicalprogress.簡(jiǎn)化的假設(shè)----沒有技術(shù)進(jìn)步Thesteady-stateequilibriumfortheeconomyisthecombinationofpercapitaGDPandpercapitacapitalwheretheeconomywillremainatrest,thatis△y=0,△k=0.經(jīng)濟(jì)穩(wěn)定的均衡狀態(tài)是人均國(guó)內(nèi)生產(chǎn)總值與人均資本額的綜合：△y=0,△k=0.Theproductionfunctioninpercapitatermsiswritteny=f(k)Ascapitalrises,outputsrises,butoutputsriseslessathighlevelsofcapitalthanatlowlevels.以人均資本為變量的生產(chǎn)函數(shù)y=f(k)隨著資本量的上升，產(chǎn)出增加，但是在人均資本額較高處，增長(zhǎng)率慢于人均資本額較低處。Fig3-3PerCapitalProductionFunction“diminishingmarginalproduct”isthekeyexplanationofwhytheeconomyreachesasteadystateratherthangrowingendlessly.邊際產(chǎn)量遞減----是為什么經(jīng)濟(jì)達(dá)到穩(wěn)定狀態(tài)，而不是永無休止的增長(zhǎng)的關(guān)鍵。STEADYSTATE（穩(wěn)定狀態(tài)）k—(tomaintainagivenlevel)dependsonpopulationgrowth(n)andthedepreciationrate(d).Assume:n≡△N/NTheinvestmentrequired=(n+d)k要使人均資本保持給定的水平，取決于人口增長(zhǎng)率和折舊率n≡人口增長(zhǎng)率所需要的投資額=(n+d)k新古典增長(zhǎng)理論的假設(shè)條件AssumenogovernmentsectorandnoforeigntradeorcapitalflowsAssumealsothesavingisaconstantfraction,s,ofincome.Percapitasaving---------sy假設(shè)沒有政府部門、對(duì)外貿(mào)易或資本的流動(dòng)假設(shè)儲(chǔ)蓄率是一個(gè)常量s則人均儲(chǔ)蓄為syInvestmentandsavingSinceincomeequalsproduction,sosy=(n+d)k△k=sy-(n+d)kthesteadystateisdefinedby△k=0sy*=sf(k*)=(n+d)k*Fig3-4SteadyStateOutputandInvestmentTHEGROWTHPROCESS

增長(zhǎng)路徑Atthatsteadystate,bothkandyareconstant.Withpercapitaincomeconstant,aggregateincomeisgrowingatthesamerateaspopulation,thatis,atraten.在穩(wěn)定狀態(tài)，k和y都是常量。由于人均收入保持不變，總收入以人口增長(zhǎng)的速度增長(zhǎng)，即n。Fig3-5IncreaseinSavingRateMovestotheSteadyStateItfollowsthatthesteady-stategrowthrateisnotaffectedbythesavingsrate.Thisisoneofthekeyresultsofneoclassicalgrowththeory.穩(wěn)定的增長(zhǎng)率不受儲(chǔ)蓄率的影響這是新古典增長(zhǎng)理論的一個(gè)重要結(jié)論。GROWTHWITHEXOGENOUSTECHNOLOGICALCHANGEFIG3-7ExogenousTechnologicalChangeRECAP總結(jié)First,thegrowthrateofoutputsinsteadystateisexogenous;inthiscaseitisequalton.Itisthereforeindependentofthesavingsrate,s.第一，產(chǎn)出的增長(zhǎng)率是外生的；在這種情形下，它等于n。因此，它是獨(dú)立于儲(chǔ)蓄率s。Second,althoughanincreaseinthesavingsratedoesnotaffectthesteady-stategrowthrate,itdoesincreasethesteady-statelevelofincomebyincreasingthecapital-outputratio.第二，盡管儲(chǔ)蓄率的增長(zhǎng)不會(huì)影響穩(wěn)定狀態(tài)的增長(zhǎng)率，但是，它會(huì)通過增加資本產(chǎn)出比率，提高穩(wěn)定狀態(tài)下的收入水平。Third,whenweallowforproductivitygrowth,wecanshowthatifthereisasteadystate,thesteady-stategrowthrateofoutputremainsexogenous.第三，允許生產(chǎn)率上升時(shí)，依然存在穩(wěn)定狀態(tài)。產(chǎn)出的穩(wěn)定增長(zhǎng)率依然是外生的。thesteady-staterateofgrowthofpercapitaincomeisdeterminedbytherateoftechnicalprogress.thesteady-stategrowthrateofaggregateoutputisthesumoftherateoftechnicalprogressandtherateofpopulationgrowth.穩(wěn)定狀態(tài)下的人均收入的增長(zhǎng)由技術(shù)進(jìn)步率決定，穩(wěn)定狀態(tài)下的總產(chǎn)出的增長(zhǎng)是技術(shù)進(jìn)步率和人口增長(zhǎng)率的總和。Thefinalpredictionofneoclassicaltheoryisthatofconvergence:iftwocountrieshavethesamerateofpopulationgrowth,thesamesavingsrate,andaccesstothesameproductionfunction,hisframework,poorcountriesarepoorbecausetheyhavelesscapital,butiftheysaveatthesamerateasrichcountriesandhaveaccesstothesametechnology,theywilleventuallycatchup.新古典增長(zhǎng)理論的最后預(yù)測(cè)是“收斂”如果兩個(gè)國(guó)家有同樣的人口增長(zhǎng)率，同樣的儲(chǔ)蓄率，同樣的生產(chǎn)函數(shù)，他們將會(huì)達(dá)到同樣的收入水平在這個(gè)理論框架下，窮國(guó)之所以窮是因?yàn)橘Y本較少，但是，如果他們和富國(guó)有相同的儲(chǔ)蓄率并能得到相同的技術(shù)落后，它們最終可以趕上富國(guó)的水平。Further,ifcountrieshavedifferentsavingsrates,thenaccordingtothissimpleneoclassicaltheory,theywillreachdifferentlevelsofincomeinthesteadystate.Butiftheirratesoftechnicalprogressandpopulationgrowtharethesame.Theirsteady-stategrowthrateswillbethesame.進(jìn)一步,如果國(guó)家之間有不同的儲(chǔ)蓄率,那么根據(jù)這個(gè)模型,他們?cè)诜€(wěn)定狀態(tài)下將會(huì)達(dá)到不同的收入水平.但是,如果技術(shù)進(jìn)步率和人口增長(zhǎng)率是相同的,他們的穩(wěn)定增長(zhǎng)率將是相同的.討論的問題中國(guó)近三十年的發(fā)展中，具有多大的作用？人口紅利消失后，如何轉(zhuǎn)變經(jīng)濟(jì)增長(zhǎng)模式？demographic

dividendPopulationdividenddemographicbonusordemographicdebt

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