《高级宏观学教学资料》ch ppt课件.ppt

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1、Ch2Infinite-horizonandOverlapping-generationsModels(无限期与跨期模型)基本思路:研究储蓄率（即资本积累）的内生性，为此引入微观经济主体（消费者）的决策行为，即消费者在预算约束条件下最大化其效用。PartA:R-C-KModel：时间连续(infinite-horizon)，没有新的家庭加入经济系统；PartB:DiamondModel：时间有限而且断续（分为两期t1、t2），有新家庭加入。PartARamsey-Cass-KoopmansModel§2.1Assumptions1.Firms:(1)Perfectcompe

2、tition;(2)Lotsofidenticalfirms→生产函数可加总;(3)δ=0(Nodepreciation).(4)Aisgiven,2.Households:(1)Alargenumberofidenticalhouseholds(共有H户);(2)Thesizeofeachhouseholdgrowsatraten;(3)1unitoflaborsuppliedbyeachmemberofthehouseholdateverypointintime;(4)Initialcapitalholdingsofthehousehold:(5)Thehousehold’

3、sutilityfunctiontakestheform:(2.1)ρ：贴现率，反映人们对未来消费与现在消费的选择偏好，当ρ↑→未来消费效用的现值↓→现在消费↑，未来消费↓。(6)Theinstantaneousutilityfunctiontakestheform:θ：Thecoefficientofrelativeriskaversionforthisutilityfunctionθ决定了家户在不同时期转移消费的意愿(2.2)该函数形式能保证经济收敛于平衡增长路径。若θ↑→u’(C)↓→对现在消费的边际效用评价↓→C↓为生命周期总效用收敛条件，见P53(2.12)§2.2B

4、ehaviorofHouseholdsandFirms1.BehaviorofFirms:Assumption：Constantreturnstoscale,perfectcompetition,firmsearnzeroprofits.(1)Themarginalproductofcapital:(资本的边际产出)r(t):Therealinterestrateattimet(2.3)(2)Themarginalproductoflabor(劳动的边际产出)(2.4)(2.5)w(t):每个有效劳动单位的边际产出（工资）W(t):单位劳动的边际产出（工资）2.Behavior

5、ofhouseholds(1)Households’BudgetConstraintThepresentvalueofitslifetimeconsumptioncannotexceeditsinitialwealthplusthepresentvalueofitslifetimelaborincome.Thepresentvalueofthehousehold’slifetimeconsumptionThepresentvalueofthehousehold’slifetimelaborincomeThehousehold’sinitialwealthTherepresent

6、ativehousehold’sConsumptionexpendituresTherepresentativehousehold’slaborincomeatt(2.6)移项得：Thenwritetheintegralfromt=0tot=∞asalimit:Thepresentvalueofthehousehold’ssavingTherepresentativehousehold’ssavingattimet(2.8)(2.7)每个家户期末（s）财富存量：期末财富期初财富在ｓ时的本息之和总储蓄的增量Thehousehold’ssavingattThevalueofthat

7、savingchangesfromttos(2.9)ThustheBudgetConstraintCanBewrittenSimplyas:(2.10)Thepresentvalueofthehousehold’sassetholdingscannotbenegativeinthelimitKnownastheno-ponzi-gamecondition庞氏骗局：不断借新债还旧债的一种欺骗行为(2)Household’smaximizationproblem:Note:Therepresen