中国棉花生产要素投入贡献率测算与分析——基于时变弹性生产函数法

Measurement and analysis on contribution rate of cotton input factors in China: Based on time-varying elasticity production function

基于产出弹性时变的特性,放宽传统生产函数假设,将棉花种植面积、单位面积物质资本投入以及单位面积劳动力投入的产出弹性看作可变参数,利用我国11个产棉省份1998—2015年棉花投入产出省际面板数据,建立时变弹性生产函数模型,用于计算各要素产出弹性,并进一步测定要素贡献率。结果表明,在中国棉花生产要素投入产出方程中确实存在时变参数,并且要素投入处于规模报酬递增状态。各要素产出贡献率呈变动趋势,其中:棉花种植面积贡献率先增后减,单位面积物质资本投入贡献率逐渐降低,单位面积劳动力投入贡献率逐渐升高,技术进步贡献率先减后增。根据各类要素贡献率变动趋势,结合中国棉花生产面临的外部环境,提出相应政策建议。

In the present study,the unreasonable neutral assumption of constant output elasticity of the Cobb-Douglas production function was broadened,and the output elasticity of cotton cultivated area,material capital and labor force investment per unit area were regarded as variable parameters. With panel data of input and output in the 11 main cotton production provinces through 1998-2015 in China,a model of variable parametric production function was proposed to calculate the elasticity of cotton input factors and to measure the contribution rate of each input factor. It was shown that time-varying parameters in the production function of cotton did exist,and the returns to scale continued to increase in recent years. Contribution rate of each input factor remained fluctuating. Specifically,the contribution rate of cotton cultivated area increased at first and then decreased,the contribution rate of material capital investment per unit area kept decreasing,the contribution rate of labor force investment per unit area kept increasing,and the contribution rate of technical progress decreased at first and then increased. According to the changing tend-ency of contribution rate of each input factor in cotton production and the external environment that cotton industry faced,policy recommendations were put forword.