经济波动与最优城镇化水平和速度研究

Economic Fluctuation and Optimal Level and Speed of Urbanization

城镇化对经济波动具有重要影响,过快和过慢均不利于经济的平稳发展。我国经济新常态客观上要求实施新型城镇化战略,关键是积极稳妥推进城镇化,科学控制城镇化水平和速度。以宏观经济稳定为目标,确定最优城镇化规则,诊断当前城镇化水平和速度,可为落实新型城镇化,稳定宏观经济提供决策参考。本文建立了附加城镇化变量的后顾型宏观经济模型,利用最优控制理论求解基于宏观经济波动最小化的最优城镇化水平和速度决定规则,实证结果表明:我国人口城镇化速度主要对宏观总需求产生影响,而土地城镇化速度既影响总需求也影响总供给;最优城镇化速度规则对总产出缺口负反馈,对通胀缺口正反馈。在此基础上,进一步模拟了1990-2013年间最优人口城镇化、土地城镇化水平以及相应的总产出和通胀波动情况,模拟结果显示:最优城镇化水平和速度规则具有逆经济周期的特征,为保持经济平稳发展,经济过度繁荣时城镇化应减速,经济衰退时应加速城镇化,我国历史上城镇化速度和水平存在较大的优化空间;最优城镇化水平和速度规则会小幅度降低城镇化进程和总产出的平滑性,但会大幅度抑制通胀波动,总体来看使总福利损失下降约三分之一;当前我国人口城镇化水平超前速度过快,土地城镇化水平偏低速度过慢。建议"十三五"期间,政府应该根据宏观经济波动情况适当控制人口城镇化速度,加快推进土地城镇化,提高土地城镇化水平和质量,同时应制定相应的财政政策和货币政策以促进最优城镇化规则发挥其降低宏观经济波动功能。

It is well known that urbanization has a pivotal role in maintaining stable and relatively fast economic growth in China, excessively fast speed or excessive slow speed is harmful to our sustained and steady economic growth. The ＂new normal＂ of China＇s economy objectively demands that promoting urbanization actively and steadily, and pursuing it in a scientific way is cruc, ial tbr implementing new type urbanization. We believe that macroeconomic stability-oriented urbanization rules setting can be reference for implementing the new type urbanization and stabilizing economy. This paper develops a backward-looking macro-economic model which includes urbanization variable,and in order to find the optimal urbanization rate setting rules, we use optimal control theory to solve a macro-economic fluctuation minimization problem. Our result indicates that China＇s population urbanization speed has a statistically significant effect on total demand, whereas land urbanization speed influences both supply and demand. We also find out that the optimal urbanization speed has a negative feedback on output gap, but a positive one on inflation gap. We then simulate the optimal population as well as land urbanization level and the corresponding total output between 1990 and 2013. The result shows that the optimal urbanization rate setting rules reverse economic direction, which means that in order to promote steady and prosperous development of economy, we should slow urbanization down when our economy experiences expansional.w booms and speed up urbanization when we are in a recession. Our historical urbanization speed and level all could be optimized further. Altlmugh ttle optimal rule of urbanization level and speed will decrease the smoothness of urbanization process as well as output, it will also have a beneficial effect on controlling inflation; overall, total welfare will be reduced by one-third. Aware of the fact that our population urbanization level rising rapidly and land urbanization level is in a slow motion, we suggest that, while accelerating the process of land urbanization and improving the level and quality of land urbanization, our government should also formulate corresponding fiscal and monetary policies to promote the macroeconomic fluctuation-reducing function of urbanization during the 13th Five Year Plan period.