人口结构变动对时间偏好的影响分析

本文从经济学角度定义了老龄化率，以便更好地刻画社会进入老龄化且老龄化程度不断变化这一现象，并将人口结构参数定义为老龄化率与人口增长率的比例。人口结构变动除影响技术进步率外，还影响家庭对未来的看法，将人口结构参数引进Ramsey模型分析对经济的影响，发现在鞍型的平衡增长路径上，人均产出增长率取决于技术进步率与老龄化率之差，而由于人口结构参数影响时间偏好，经济增速最大化与社会福利最大化所要求的人口结构参数出现了不一致，本文给出了两种情形下的必要条件，并进行数值模拟。

The Effect of Population Structure on Time Preference

Based on the definition of aging rate, the population structure is defined as the ratio of aging rate and population growth rate. This structure influences time preference, and is analyzed in Ramsey model. In the saddle balanced growth path, the output growth rate per capita depends on the difference between the technical progress rate and the aging rate. However, the optimal structure in social welfare maximum is not the same as the one in the output growth maximum. The function simulation is also conducted based on the corresponding first order conditions. In order to analyze the influence of population structure parameters on economic system, a special situation is considered. The aging rate is a fixed proportion of the population growth rate and the population growth rate does not affect population structure parameters. The maximization of economic growth requires that the marginal impact of population structure parameters on technological progress is equal to the growth rate of the total population. In order to simplify the analysis of social welfare, the assumption that the technological progress rate is equal to the rate of ageing is given and then the first order condition of the optimal population structure parameters corresponding to social welfare maximization is obtained. The marginal effect of population structure parameters on the utility discount factor should be equal to zero.