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SESEVENTEDITION.Gregory®SlidesbyRonCHAPTE EconomicGrowthII:ModifiedforECbyBob©2010Worth Inthischapter,youwillhowtoincorporatetechnologicalprogressintheSolowmodel索洛模型中的技术进步aboutpoliciestopromotegrowth促进增长的aboutgrowthempirics:confrontingthetheorywithfacts增长的经验：理论与事实的twosimplemodelsinwhichtherateoftechnologicalprogressisendogenous两个内cIlprogress3IntheSolowmodelofChapter7,第7章介绍的Solow模theproductiontechnologyisheldconstant. epercapitaisconstantinthesteadystate.稳定状态Neitherpointistrueintherealworld:但以上两点在实际1908-2008:U.S.realGDPper grewbyafactorof7.8,or2.05%peryear.1908-2008:U.S.人均实际GDP平均每年增长2.05%，总共增长了7.8倍.CHCH EconomicGrowth4Examplesoftechnological技术进步的例From1950to2000U.Sfarmsectorproductivitynearlytripled从19502000，农业部门生产率翻了近三Therealpriceofcomputerpowerhasfallena ageof30%peryearoverthepastthreedecades.计算机的实际价格在过去的三十年中平均每年PercentageofU.S.householdswith≥1computers:8%in1984,62%2003家庭拥有大于1台电脑的比例：1984年8%，2003年1981:213computersconnectedtotheInternet213台计算机组成2000:60millioncomputersconnectedtotheInternet6000万台计算机Internet连2001:iPodcapacity=5gb,1000songs.NotcapableofplayingofTrue 2001年，iPod容量=5gb，10002009:iPodcapacity=120gb,30,000songs.CanplayepisodesofBlood.2009年：iPod容量=120gb，三万首歌。并且可以美剧《真CHAPTERCHAPTER EconomicGrowthTechnologicalprogressintheSolow Solow模型中的技术进步Anewvariable:ElaborefficiencyTechnologicalprogressislabor-itincreaseslaborefficiencyattheexogenousrateg:技术进步是劳动改善型的每单位的劳动效率以外生比率g增加TechnologicalprogressintheSolowWenowwritetheproductionfunctionwhereL×E=thenumberofeffectiveIncreasesinlaborefficiencyhavethesameeffectonoutputasincreasesinthelaborforce.因此，劳动效率的提高与增加劳动TechnologicalprogressintheSolowyY/LEoutputpereffectiveworker单位有k=K/LE=capitalpereffectiveProductionfunctionpereffectivey=Savingandinvestmentpereffectivesy=sf(k)TechnologicalprogressintheSolow(+n+g)k=break-eventheamountofinvestmenttokeepkconstant.保持kConsistsktoreplacedepreciatingcapitalnktoprovidecapitalfornewworkersgktoprovidecapitalforthenew“effective”workerscreatedbytechnologicalprogress提供由于技术进步而TechnologicalprogressintheSolow

k=sf(k)-(+n(+n+g)k CapitalCapitaleffectiveOutputpereffectiveworkerk=CapitaleffectiveOutputpereffectiveworkerk=K/(L×E0y=Y/(L×E0Outputper(Y/L)=gY=n+TheGoldenRulewithtechnologicalprogress技术进步下的黄金律IntheGoldenRulesteadystate,themarginalproductofcapitalnetofdepreciationequalsthepop.growthrateplustherateoftech增长率与技术进步的和TofindtheGoldenRuleIntheGoldenRulesteadystate,themarginalproductofcapitalnetofdepreciationequalsthepop.growthrateplustherateoftech增长率与技术进步的和 =f(k*)—— +n+g)c* izedMPK=+n+orMPK- =n+CHAPTER EconomicGrowth Growthempirics:BalancedSolowmodel’ssteadystatebalancedgrowth-manyvariablesatthesamerate.索洛模型的稳定状态表现出平衡的增长，SolowmodelpredictsY/LandK/Lgrowatthesamerate(g),soK/Yshouldbeconstant.Thisistrueintherealworld.SolowmodelpredictsrealwagegrowsatsameasY/L,whilerealrentalpriceisconstant.Alsotrueintherealworld. CHAPTER EconomicGrowth Growthempirics:ConvergenceSolowmodelpredictsthat,otherthingsequal,countries(withlowerY/LandK/L)shouldgrowfasterthan“richones.索洛模型预测，其他方面相同，贫穷国Iftrue,thenthe egapbetweenrich&poorcountrieswouldshrinkovertime,causinglivingstandardsto“converge.”如果正确，富国和穷国间的收入差距将会逐Inrealworld,manypoorcountriesdoNOTgrowthanrichones.DoesthismeantheSolowmodelfails? CHAPTER wth CHAPTERCHAPTER EconomicGrowthGrowthempirics:SolowmodelpredictslowerY/LandK/L)

“poor”countriesotherthingsgrowfasterthanotherthingsNobecauseotherthingsaren’tequal.不，因为“其他方面”不会同Insamplesofcountrieswithsimilarsavings&pop.growthegapsshrinkabout2peryear.样本中有着类似储蓄，人口增长的国家间，收入差距每年以2%的速度缩Inlargersamples,aftercontrollingfordifferencesinsaving,pop.growth,andhumancapital, esconvergebyabout2%peryear.在更大的样本中，在控制了储蓄和人口增长，人力资本等差别后，入将以每年2%的速度趋Growthempirics:WhattheSolowmodelreallypredictsisconditionalconvergence-countriesconvergetotheirownsteadystates,whicharedeterminedbysaving,populationgrowth,andeducation.ThispredictioncomestrueintherealGrowthempirics:Fductionefficiency要素积累和生产效率Differences epercapitaamongcountriescanduetodifferencesin: capitalphysicalorhumanperworker theefficiencyofproduction(theheightoftheproductionBothfactorsareimportant.Thetwofactorsarecorrelated:countrieswithhigherphysicalorhumancapitalperworkeralsotendtohave

utefenc.CHAPTERCHAPTER EconomicGrowthGrowthempirics:FductionefficiencyPossibleexplanationsforthecorrelationbetweencapitalperworkerandproductionefficiency:对人均资本和生产ProductionefficiencyencouragesaccumulationCapitalaccumulationhasexternalitiesthatefficiency.Athird,unknownvariablecausescapitalaccumulationandefficiencytobehigherinsomecountriesthanothers.第三个未知变量驱动一些国家GrowthProductionefficiencyandfreetrade生产SinceAdamSmith,economistshavearguedfreetradecanincreaseproductionefficiencyandlivingstandards.从亚当斯密以来，就提出自developedResearchdevelopedoi1GrowthGrowthProductionefficiencyandfreetrade生产Todeterminecausation,FrankelandRomerexploitdifferencesamongcountries:为了找到原因，克尔和罗默提出了Somenationstradelessbecausetheyarefartherfromothernations,orlandlocked.一些国家贸易较少是因为他们与其他国家距离很远，Suchgeographicaldifferencesarecorrelatedwithtradebutnotwithotherdeterminantsofe.这种地理上的差异与贸易相关但和收入的Hence,theycanbeusedtoisolatetheimpactoftradeon e.因Findings:increasingtrade/GDPby2%causesGDPpercapitarise1%otherthings 研究发现：贸易与GDP之比上升2%CHAPTERCHAPTER EconomicGrowthPolicyissuesArewesavingenough?Toomuch我们的储蓄够吗？还是太多了Whatpoliciesmightchangethesavingrate?什么政策能够改变储率Howshouldweallocateourinvestmentbetweenpriva yownedphysicalcapitalpublicinfrastructure,andhumancapital”?我们应该Howdoacountry’sinstitutionsaffectproductionefficiencycapitalaccumulation?一国机构如何影响生产效率和资本积累Whatpoliciesmightencouragefastertechnological什么政策可以鼓励更快的技术进步CHAPTERCHAPTER EconomicGrowthPolicyEvaluatingtherateofUsetheGoldenRuletodeterminetheU.S.savingrateandcapitalstockaretoohigh,toolow,oraboutright.利用黄金规则来决定的储蓄率和资本存量太高，太低还是正好If(MPK-)>(n+gU.S.isbelowtheGoldenRulesteadystateandshouldincreases.If(MPK-)<(n+gU.S.economyisabovetheGoldenRulesteadystateandshouldreduces.CHAPTERCHAPTER EconomicGrowthPolicyEvaluatingtherateofToestimate(MPK- ),usethreefactsabouttheU.S.economy:为了估算的(MPK−δ),我们采用经济的三k=2.5Thecapitalstockisabout2.5timesoneyear’sGDP.量是一年GDP的2.5k=0.1About10%ofGDPisusedtoreplacedepreciating资本折旧约为GDP的MPK×k=0.3 eisabout30ofGDP.资本收入约为GDPPolicyEvaluatingtherateofk=2.5k=0.1MPK×k=0.3Todetermine,divide2byPolicyEvaluatingtherateofk=2.5k=0.1MPK×k=0.3TodetermineMPK,divide3byHence,MPK-=0.12-0.04=PolicyEvaluatingtherateofFromthelastslide:MPK-=U.S.realGDPgrowsa ageof3%peryear,son+g=0.03CHAPTER EconomicGrowthTheU.S.isbelowtheGoldenCHAPTER EconomicGrowthTheU.S.isbelowtheGoldenRulesteadystate:IncreasingU.S.savingratewouldincreaseconsumptionpercapitainthelongrun. 经济在低于黄金规则稳定状态资本存量下运行:如CHAPTERCHAPTER EconomicGrowthPolicyHowtoincreasethesavingrateReduce

ernmentbudgetdeficit减少赤(orincreasethebudgetsurplus)或增加盈Increaseincentivesforprivatesaving:reducecapitalgainstax,corporate etax,estatetaxastheydiscouragesaving.降低资本利得税、公司所得税、税replacefederal etaxwithaconsumptiontax.将expandtaxincentivesforIRAs(individualretirementaccounts)andotherretirementsavingsaccounts.增大对CHACHAPTEooPolicyAllocatingtheeconomy’sIntheSolowmodelthere’sonetypeofcapital.Intherealworld,therearemanytypes,whichwecandivideintothreecategories:实际经济中，存在多种资本，privatecapitalstockpublicinfrastructurehumancapital:theknowledgeandskillsthatworkersacquirethrougheducation人力资本：工人通HowshouldweallocateinvestmentamongtheseCHAPTERCHAPTER EconomicGrowthPolicyAllocatingtheeconomy’sTwoviewpoints:Equalizetaxtreatmentofalltypesofcapitalinallindustries,thenletthemarketallocateinvestmenttothetypewiththehighestmarginalproduct.对任何行业的任Industrialpolicy:tshouldactivelyencourageinvestmentincapitalofcertaintypesorincertainindustries,becausetheymayhavepositiveexternalitiesthatprivateinvestorsdon’tconsider.产业政策:应该PossibleproblemsindustrialpolicyThetmaynothavetheabilityto“pickwinners”(chooseindustrieswiththehighestreturntocapitalorbiggestexternalities).可能没有能力选择出Politics(e.g.,ncontributions)ratherthaneconomicsmayinfluencewhichindustriesgetpreferentialtreatment政治的(如：竞选捐款)而不是CHAPTERCHAPTER EconomicGrowthPolicyEstablishingtherightinstitutions建立Creatingtherightinstitutionsisimportantforthatresourcesareallocatedtotheirbestuse.Examples:Legalinstitutionstoprotectpropertyrights.护Capitalmarkets,tohelpfinancialcapitalflowtothebestinvestmentprojects.资本市场，帮助流向最Acorruption-free ernmenttopromotecompetition,enforcecontracts,etc.没有的，促进竞争，CHAPTCHAPTER8EcooII虑的问题PolicyEncouragingtech.Patentlaws:encourageinnovationbygrantingtemporarymonopoliestoinventorsofnewproducts.通过允许暂时独占新发现成TaxincentivesforR&D对R&D的激Grantstofundbasicresearchatuniversities支持大学基Igress(subjecttotheprecedingconcerns).产业政策:鼓励发展那些能够促进技术进步的关键行业（但有CASESTUDY:案例研Theproductivityslowdown生产率Growthinoutput(percentperCHAPTERCHAPTER EconomicGrowthPossibleexplanationsfortheproductivityslowdown生产率减缓的解Measurementproblems:衡量问Productivityincreasesnotfullymeasured.But:Whywouldmeasurementbeworseafter1972than Oilshocksoccurredaboutwhenproductivityslowdownbegan.石油价格冲击差不多在生产率减缓时发生But:Thenwhydidn’tproductivityspeedupwhenoilpricesfellinthemid-1980s?但是在80年代中期石油CHAPTERCHAPTER EconomicGrowthPossibleexplanationsfortheproductivityslowdownWorkerquality:工人的素1970slargeinfluxofnewentrantsintolaborforcebabyboomers,women).70年代初，大批一代和妇女进Newworkerstendtobelessproductivethanexperiencedworkers.新进入的工人比有经验的工人生产Thedepletionofideas:思想的枯Perhapstheslowgrowthof1972-1995isnormal,andtherapidgrowthduring1948-1972istheanomaly.也许Whichofthese sistheculprit?以Allofthemareplausible,butit’sdifficulttoprovethatanyoneofthemisguilty.CASEI.T.andthe“NewGrowthinoutput(percentpercooCASESTUDY:案例研I.T.andthe“NewApparently,thecomputerrevolutiondidnotaffectaggregateproductivityuntilthemid-1990s.很明显，计算TwoComputerindustry’sshareofGDPmuchbiggerinlate1990sthanearlier1990s，计算机产业在GDP中的比过去更高Takestimeforfirmstodeterminehowtoutilizenewtechnologymosteffectively企业需要时间来消化如何Thebig,openHowlongwillI.Tremainanengineofgrowth?I.TCHAPTERCHAPTER EconomicGrowthEndogenousgrowththeory内生增长理Solowsustainedgrowthinlivingstandardsisduetotechprogress生活水平的持续提高是由于技术therateoftechprogressisexogenous技术进Endogenousgrowthasetofmodelsinwhichthegrowthrateofproductivityandlivingstandardsisendogenous.AbasicmodelProductionfunction:Y=AwhereAistheamountofoutputforeachunitofcapitalAisexogenous&constant)A为每一单位资Keydifferencebetweenthismodel&Solow:MPKisconstanthere,diminishesinSolow该模型与索洛Investment:sDepreciation:Equationofmotionfortotalcapital:K=sY-AbasicK=sY-DividethroughbyKanduseY=AKtoIfsA> ,then ewillgrowforever,andinvestmentisthe“engineofgrowth.”如果sA>δ,则收入将持续增长,投资是“增长引擎”Here,thepermanentgrowthratedependss.InSolowmodel,itdoesnot.持续增长速度取决于s，而Solow模型则不是这样CHACHAPTDoescapitalhavediminishingreturnsornot?资本收益是否递减？Dependsondefinitionof“capital.”Ifcapitalisnarrowlydefinedonlyplant&equipment),thenyes.如何是狭义的资本（只有工厂和设备），那Advocatesofendogenousgrowththeoryarguethatknowledgeisatypeofcapital.内生增长理论的支持者认Ifso,thenconstantreturnstocapitalismoreandthismodelmaybeagooddescriptionofeconomicgrowth.如果是这样，那么资本收益不变更加合理。假设CHAPTERCHAPTER EconomicGrowthAtwo-sectormodelTwomanufacturingfirmsproducegoods.制造业企业生产researchuniversitiesproduceknowledgethatincreaseslaborefficiencyinmanufacturing.研究性大ufractionoflaborinresearch(uisMfgprod Y=F[K,(1-u)EResprodfunc:E=g(uCapaccumulation:K=sY-CHCHP onAtwo-sectorInthesteadystate,mfgoutputperworkerandthestandardoflivinggrowatrate在稳E/E=g(uKeyvariables: affectsthelevelof e,butnotitsgrowthratesameasinSolowmodel)影响 affectslevelandgrowthrate eDISCUSSIONThemeritsofraising“u”提高uWouldanincreaseinubeunambiguouslygoodfortheeconomy?u的上升对经济只有Whyorwhynot?FactsaboutR&DMuchresearchisdonebyfirmsseekingprofits.许多研究是企业追利润的结Firmsprofitfromresearch企业从研究中获得利Patentscreateastreamofmonopolyprofits.专利创造了利Extraprofitfrombeingfirstonthemarketwithanewproduct.一种新产品进入市场的第一家企业的额外Innovationproducesexternalitiesthatreducethecostofinnovation.创新产生的外部性减少了往后创新的成Muchofthenewendogenousgrowthattemptstoincorporatethesefactsintomodelstobetterunderstandtechnologicalprogress.大多数的内生增长理论试图将这些事实引入到模中，以更好的解释技术进CHAPTER EconomicGrowth IstheprivatesectorngenoughTheexistenceofpositiveexternalitiesinthecreationknowledgesuggeststhattheprivatesectorisnot enoughR&D知识创造正的外部性的存在表明私人部门在R&DBut,thereismuchduplicationofR&Deffortamongcompetingfirms.但是，在竞争的厂商间有许多研究努力的重复SocialreturntoR&D40peryear.每年R&D的社会收益≥Thus,manybelieve