Optimal investment with vintage capital: Equilibrium distributions

The paper concerns the study of equilibrium points, or steady states, of economic systems arising in modeling optimal investment with vintage capital, namely, systems where all key variables (capitals, investments, prices) are indexed not only by time but also by age. Capital accumulation is hence described as a partial differential equation (briefly, PDE), and equilibrium points are in fact equilibrium distributions in the variable of ages. A general method is developed to compute and study equilibrium points of a wide range of infinite dimensional, infinite horizon, optimal control problems. We apply the method to optimal investment with vintage capital, for a variety of data, deriving existence and uniqueness of equilibrium distribution, as well as analytic formulas for optimal controls and trajectories in the long run. The examples suggest that the same method can be applied to other economic problems displaying heterogeneity. This shows how effective the theoretical machinery of optimal control in infinite dimension is in computing explicitly equilibrium distributions. To this extent, the results of this work constitute a first crucial step towards a thorough understanding of the behavior of optimal paths in the long run.     

中日韩自由贸易区的贸易流量和福利效应分析:一个局部均衡的校准方法

校准方法作为一种确定数理经济模型中的变量和参数的手段之一,在贸易政策的建模研究中得到广泛的应用.本文以局部均衡为基础,利用中日韩三国自1990～2003年共14年的贸易额及相关数据建立校准模型,并对拟议中的中日韩自由贸易区做出比较静态分析,从产业层面来模拟中日韩自由贸易区建成后所可能带来的福利效应.分析结果表明,中日韩三国建立自由贸易区会增加彼此的国民福利水平,并会对未加入贸易协定的其他东亚国家产生影响.因此,在东亚形成更为广泛的自由贸易安排从区域合作的角度来看是一种更佳的合作方式.     

区域经济学主流化的新格局:迈向新综合的空间一般均衡理论

区域经济学的研究从1990年后，日趋活跃、争论纷呈，在某种意义上讲，发生了很大的转向。即由克鲁格曼发轫的新经济地理把该领域的某些问题带向经济学主流的一般均衡分析框架下来讨论，他们更加宏伟的蓝图是要实现具有新综合特征的空间一般均衡理论，为区域经济学的研究注入了新的活力。该文简述了这些新理论的基本模型、主要特征和模型的扩展及对经济体系空间特性研究的主要贡献，以及由之而引起的各方面的争论和共识。     

独立审计质量的经济学透视

本文从需求和供给两方面分析了独立审计市场中的审计质量均衡状况及其成因,研究发现:一方面,由我国公司治理不完善而引发的对独立审计的代理需求不足,以及特定融资制度下对低质量审计的融资需求强劲,使得我国独立审计的自愿性需求严重匮乏,从而审计师缺乏提高审计质量的内在经济动机;另一方面,现有法规对审计师的激励不足、约束不够,因此目前审计师提供的审计服务质量难于达到社会公众的期望-《独立审计准则》的要求.最后,笔者针对出现的问题提出相应的政策建议.     

Playing safe in coordination games:: the roles of risk dominance, payoff dominance, and history of play

This paper presents results from a series of experiments designed to test the impact on subject behavior of changes in the risk dominance and payoff dominance characteristics of two player coordination games. The main finding is that changes in risk dominance significantly affect play of the subjects, whereas changes in the level of payoff dominance do not. Observed history of play also has an important influence on subject behavior, both when subjects are randomly rematched after each game and when they remain matched with the same individual for a sequence of games.     

对我国医药企业自主创新演化机制的分析

自主创新是当前商业界和学术界研究比较热的话题。政府相应地制定了一系列的政策和法规来鼓励企业进行自主创新。在这种背景下,我国的医药企业也积极响应国家的政策进行自主创新。然而,医药企业创新在实际操作中的行动方向差异很大。针对这种差异,笔者将医药企业创新划分成新功能创新和新设计创新两种,并且通过对一系列的数据和资料分析后,发现我国的医药企业的创新并非实质上的自主创新即新功能创新,而是新设计创新。文中对产生这种局面的演化机制进行了分析。     

Selection dynamics and adaptive behavior without much information

This paper uses the experimental method to investigate behavior in a coordination game when the information available to subjects is limited to their feasible choices and their experienced payoffs. In the experiment subjects converge to an absorbing state at rates that are orders of magnitude faster than reinforcement learning algorithms, but slower than under complete information. This state is very close to a mutual best response outcome. All cohorts converged to the market statistic predicted by the interior equilibrium regardless of the information conditions or the stability conditions. Eric Battalio programmed the graphical user interface. The National Science Foundation and Texas Advanced Research Program provided financial support. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation or the Texas Advanced Research Program.     

均衡与演化——对经济学发展方向的思考

经济学研究中的均衡主义与演化主义历来存在争论.本文在对经济均衡主义和演化主义的形成、内容及特征详细分析的基础上,对经济学体系的发展状况进行了初步的检讨.本文认为,对均衡主义与演化主义在一个更为一般的框架内进行整合和创造性发展,具有重大的理论价值.     

对西方主流宏观经济学均衡假定的反思——从凯恩斯主义的投资恒等于储蓄说起

自从凯恩斯的《通论》出版以来,宏观经济学就逐渐成为一个比较系统而相对独立的学科,后人将凯恩斯的短期经济增长模型进一步长期化为外生和内生经济增长理论.纵观主流宏观经济学的理论构建,几乎都有一个共同的假设:市场能够自动实现均衡,但是,正是这个假设将西方主流宏观经济学引入了歧途.对于原凯恩斯主义、新古典综合派、新凯恩斯主义、哈罗德-多马的古典经济增长理论和索洛的新古典增长理论、新古典宏观经济学派而言,它都是一个难以回避的硬伤.     

个人教育投资的均衡分析

人力资本投资的关键形式是教育投资。文章认为,个人教育投资的均衡条件是边际成本等于边际收益。因为个人教育投资的边际成本递增,边际收益递减,所以必须采取多种措施刺激个人教育投资的积极性,才能促进我国教育事业的大发展。