发展经济学-3.pptx

Theories of Development:A Comparative AnalysisChapter 3Leading Theories of Economic Development:Five ApproachesnClassical Scenario 古典经济增长理论nLinear-stages-of-growth model 线性增长模型nNeoclassical models 新古典增长模型nEndogenous growth 内生经济增长模型亚当斯密与报酬递增n产出、生活水平提高资本积累利润的储蓄工业和农业的专业化劳动分工n劳动分工决定了劳动生产率。劳动分工提高劳动生产率有三种途径：1、工人工作技能的提升，即边干边学。2、分工的细化节省了在不同工作间转移的时间。3、机器的发明使同一个劳动者可以从事多种工作。n劳动分工受到市场规模的限制。1、如机器的使用只有在市场规模较大情况下才有经济性，否则就会出现剩余产品。2、自由贸易对市场规模的扩大有着积极的意义。n斯密的报酬递增观点是新内生经济增长理论的核心思想古典悲观主义TP*TPOW subsistence wage linePE2W2W1E1N1N2LaborTotal productionOriginal condition:Labor:ON1Production:OPWage:N1W1Surplus:E1W1Demand for labor increaseWages increase to E1N1N1W1According to Malthusian theory of population,population will increase to ON2;Surplus appear again E2W2Equilibrium point:ETechnology development:E*,the day of doom can not be eliminatedEE*Limitations of the classical model nThe role of technology development has been grossly underestimatednThe Malthusian theory of population growth has been proved to be misleading:whenever wages are above level of subsistence,population will increase?nToo aggregated and did not account for the diversities with labor and capital inputThe Linear-Stages TheorynRostows stages of growthnThe Harrod-Domar growth modelnObstacles and constraintsnSome criticisms of the stages modelRostows stages of growthnThe Transition from underdevelopment to development can be descried in terms of a series of steps or stages through which all countries must proceed the traditional society the pre-conditions for take-off into self-sustaining growth the take-off the drive to maturity the age of high mass-consumptionn三种不同的增长率：实际增长率g;有保证的增长率gw;自然增长率gnn实际增长率 The Harrod-Domar Model(3.1)(3.2)(3.3)(3.4)v:capital-output ratio;S:saving ratio;S:total saving;Y:total output;K:capital stock;I:total investmentn有保证的增长率：这样一种增长率将引诱投资刚好等于计划的储蓄，保持资本完全被就业，从而制造商愿意在未来以过去相同的比例进行投资The Harrod-Domar Model(3.5)(3.6)(3.7)Harrod-Domar theory of economic growthnThe rate of growth of economic output I s determined jointly by the national saving ratio S and national capital-output ratio KnThe main obstacle on development is the relatively low level of new capital formation in most poor countriesnJustifying massive transfers of capital and technical assistance from developed to less developed nationsnSaving and investment is the necessary condition for economic growth but not the sufficient conditionnHow about the ability of converting new capital effectively into high levels of output managerial competence;skilled labor;well-integrated commodity and money market;institutional settings;infrastructuresCriticism of Harrod-Domar modelStability of economic growth-Harrodian knife-edgen保证均衡增长：g=gwn一旦偏离均衡，即实际增长率与有保证增长率出现偏差，则这种偏离不会自行矫正，反而会加重n如实际增长率低于有保证的增长率，在初期储蓄率相同情况下，实际的资本产出比大于有保证的资本产出比，将出现资本品过剩，投资受到抑制，储蓄率进一步下降，投资受到抑制，使实际增长率更低于均衡增长率n如实际增长率高于有保证的增长率，则实际的资本产出率低于有保证的资本产出率，资本品不足会刺激投资，导致实际增长率进一步增大，更加偏离有保证的增长率，使得资本品更加不足Stability of economic growth-Harrodian knife-edgeStability of economic growth-Harrodian knife-edgen黄金时代定理:actual growth rate=warranted growth rate=natural growth rate of the labor force.Thus n=s/v is the necessary condition for economic growth.（Joan Robinson：Golden Age rule，Cambridge University）n自然增长率-取决于劳动力的增长速率和劳动生产率的增长速率 nBut s,v and n are determined independently and there is nothing that guarantees that s/v will be equal to n.thus the golden rule is very hard to achieve.nIt is a knife-edge growth rate(very unstable system,with no mechanism to bring the economy back to the equilibrium growth rate).nWhen the economy is growing fast,it continues to grow even faster and goes beyond full employment(i.e.high inflation),but when growth is slow,it continues to grow even slower(i.e.high unemployment).发展中国家的情况n自然增长率高于有保证的增长率n意味着有效劳动力增长高于资本积累速度，导致失业日益增长n意味着计划投资高于计划储蓄，产生通货膨胀压力n要使自然增长率趋近有保证的增长率 1、控制人口规模 2、控制劳动生产率增长幅度：效率与就业的冲突 3、提高储蓄率 4、使用劳动密集型技术降低所要求的资本产出比Neoclassical growth modelnIn the Harrod-Domar growth model,steady-state growth was unstable.In the popular term of the day,it was a knife-edge in the sense that any deviation from that path would result in a further move away from that path nRobert M.Solow(1956),Trevor Swan(1956)and James E.Meade(1961)contested this conclusion.They claimed that the capital-output ratio of the Harrod-Domar model should not be regarded as exogenous.nNeoclassical model:the capital-output ratio,v,was precisely the adjusting variable that would lead a system back to its steady-state growth path,i.e.that v would move to bring s/v into equality with the natural rate of growth(n).The resulting model has become famously known as the Solow-Swan or simply the Neoclassical growth model.新古典增长理论的三个基本命题n在长期稳定状态，产出的增长来自于有效的劳动力增长率（即劳动力的增长率加上劳动生产率的增长率），与储蓄率无关，更高的储蓄或投资比率被更高的资本产出比抵消。n人均收入水平取决于储蓄率或投资GDP比率，与人口增长率呈反比。n资本劳动比和资本生产率的反向关系使得发展中国家在人均资本数量较少的情况下拥有更高的短期经济增长速率，各国的人均收入和生活水平应该趋同。索罗模型n1956年，开创性贡献对经济增长理论的一个贡献n1987年，索罗获得诺贝尔经济学奖n索罗模型的三个基本假定：1、世界上每一个国家只生产和消费相同商品；2、国家与国家之间不存在贸易关系；3、技术是外生的：公司可利用的技术游离于公司之外，不受公司行为的影响。n索罗模型的三个技术假定 1、劳动力以外生的不变速率增长 2、产出是劳动和资本的函数，生产函数规模报酬不变，单个生产要素符合报酬递减规律。3、所有储蓄都用于投资。基本索罗图n两条曲线的差值：劳动力人均资本的变化量；n差值为正：人均资本增加，叫做“资本深化”n差值为零：人均资本不变，人口增加带来资本总量增加，叫做“资本拓宽”n稳定状态：人均资本量保持不变(越过稳态之后如何演变)比较静态分析：模型参数变化对模型的影响投资率增加，资本进一步深化，稳定状态下的劳动力人均资本进一步增加人口增长率增加，资本被稀释，稳定状态下的劳动力人均资本减少稳定状态的性质n人均资本存量随时间变化率为零转型动态分析从非稳态向稳态过渡过程中，经济增长速率的变化转型动态分析n人均资本量的变化率：当经济体低于其稳定状态越远，则增长率越大；经济体高于其稳态越远，经济体衰退越快。n稳定状态意味着增长停滞。Technology development and Solows model引入技术进步的索罗图Characteristics of equilibrium pointa)After the equilibrium point,the growth of output per labor is jointly determined by technology development ratio,investment ratio,population growth ratio,depreciation ratio of capitalnGrowth rate:ns and n influence the absolute level but not the growth rate of long-term output per laborttgt*t*Horizontal effect劳动力人均产出增长率随时间的变化率n在索罗模型中，投资率的上升会提高经济增长率，但它只能短期地存在于经济转型到新地稳定状态地过程中，投资率地上升不会产生长期地增长效应。n投资率的上升会产生水平效应，持续的投资率的上升或下降能够持续地提高或降低人均产出的水平。索罗模型的评价n造成人均收入差异的主要原因？各国不同的投资率、人口增长率、外生技术因素；富国投资率高而人口增长率低。n经济持续增长的动力？技术进步克服了资本的边际报酬递减；长期一国的经济增长与技术增长同比率n不同国家经济增长率的差异？外生的各国技术进步的差异；同时利用转型动态分析可知在转型动态过程中，如果经济体的资本技术比率低于其长期水平，则经济体以较快速度增长直至稳定状态Growth accountingGrowth rate of GDPContribution to growthGrowth rate of GDP per laborcapitallaborTFP1960-19704.00.81.21.92.21970-19802.70.91.50.20.41980-19902.60.80.71.01.51960-19903.10.91.21.11.4考虑人力资本情况下的索罗模型n人力资本：承认在不同经济中劳动力会有不同的教育水平和工作技能扩展的索罗模型（续）扩展的索罗模型的基本发现：国家富裕是因为在扩展的索罗模型的基本发现：国家富裕是因为在物质资本中有较高的投资率、花很多时间学习以物质资本中有较高的投资率、花很多时间学习以掌握技能、低的人口增长率、先进的技术；稳定掌握技能、低的人口增长率、先进的技术；稳定状态下，人均产出以技术进步率增长状态下，人均产出以技术进步率增长不同国家间经济增长率的差异n趋同现象：在某种环境下，后进国家有望比富裕国家以高的增长率增长，从而降低两类国家间的经济差距n实证情况：a)日本、德国、美国、英国的人均GDP增长在18802000年间交替上升b)工业化国家和OECD国家的实证：人均GDP与增长率之间强烈负相关c)世界范围内则缺乏趋同现象1.两个国家处于相同技术水平，投资率、人口增长率等均相近，初始资本技术比率不同，则有可能趋同2.国家间投资率、人口增长率、技术水平差异太大，则无法趋同转型动态原理n经济体低于稳态越多，增长越快；经济体高于稳态越多，增长越慢。n新古典经济增长理论对国家间经济增长率差异的解释：没有到达自己稳态的国家将不会以相同的增长率增长。低于稳态的国家增长得快一些，高于稳态的国家增长得慢些。