中国经济国民投资率的福利经济学分析

本文首次系统地从福利经济学角度出发,运用前沿计算方法,试图回答中国投资率是否过高这一重要问题。本文首先计算了两个投资率:一是境内投资率;二是国民投资率,即(境内投资+对外投资)/GDP。通过横向的对比,发现无论是境内投资率还是国民投资率,即便考虑高经济增长率,中国经济都远高于世界各国。其次,采用经济增长理论的基准模型,利用中国的参数进行校准,并且进行稳健性检验,运用逆向积分法模拟中国经济福利最大化的投资路径。结果表明,中国经济上世纪90年代平均境内投资率低于福利最大化的投资率6%,国民投资率4%;2002年后,平均境内投资高于福利最大化的投资率5%,国民投资率12%;1990—2008年实际投资相对福利最大化的投资路径总福利损失约为5.9%,相当于每期损失约3.8%的GDP。最后,本文进一步分析,如果适当地降低国民投资率,同时改善投资效率,中国经济的GDP增长率并不会大幅下降。

A Welfare Economics Analysis of the Chinese Economic Growth

China's macroeconomic investment rate seems to be very high in comparing with the world average and that of similar emerging market economies.Is China over-investing? Existing research focuses on the rate of turn of investment in order to answer this question.We believe that this is wrong since the ultimate measure should be social welfare.However,such analyses are missing in the literature.In the paper,we first construct two measures of China's investment rate:the domestic investment rate and the national investment rate,which incorporates China's current account surplus.We then build a benchmark of growth model and then explore the method of backward integration to solve the model.Finally,we compare the optimal investment path of the benchmark model with the actual one and calculate the welfare loss due to the deviation the actual investment rate from the optimal one.We find that China 's average domestic investment rate and national investment rate are 6% and 4% lower than benchmark rate in the 1990s,respectively.However,after 2002,they are 5% and 12% higher than welfare maximizing rate,respectively.As a result,between 1990 and 2008,the total welfare loss is 5.9%,corresponding to 3.8% GDP annually.