基于半参数Copula方法的蔬菜收入保险定价研究

Vegetable income insurance pricing: Based on semi-parametric Copula method

农业保险是保障农户收益和稳定农业生产的重要政策工具。基于2004至2016年大城市番茄、黄瓜、菜椒和白菜四种蔬菜的单产和价格数据,采用核密度估计方法拟合了蔬菜产量波动和价格波动的边缘分布,并借助半参数Copula方法估计了产量和价格波动的联合分布函数。在此基础上计算了产量波动和价格波动的关联程度以及不同保障水平下产量保险、价格保险和收入保险的纯费率。研究表明:1)与其他Copula函数相比,t-Copula函数更适合拟合蔬菜产量波动和价格波动的联合分布;2)蔬菜的产量和价格呈负相关关系,蔬菜的产量风险和价格风险可以部分对冲;3)不同品种的蔬菜适用不同类型的农业保险,价格保险适合保障产量和价格负相关性弱的品种,而收入保险适合保障产量和价格负相关性强的品种;4)在70%～90%的保障水平下,我国大中城市的收入保险费率分别为番茄7.97%～21.08%、黄瓜4.03%～14.41%、菜椒3.90%～13.04%、白菜1.45%～9.32%。

Agricultural insurance is an important policy tool to protect farmers’ income and to stabilize agricultural production. Based on the yield and price data of tomato, cucumber, bell pepper, and cabbage in large and medium-sized cities from 2004 to 2016, and applying the semi-parametric Copula method, this paper analyzed the edge distribution of vegetable yield fluctuation, price fluctuation, and the joint distribution function of yield and price fluctuation. In addition, this paper also examined the correlation degrees between output and price fluctuations and the pure premiums of production insurance, price insurance and income insurance under different coverage levels. Results show that:1) The t-Copula function is more suitable for fitting the joint distribution of vegetable yield fluctuations and price fluctuations than other Copula functions;2) There is a negative correlation between the yield and price of vegetables,and the productivity risk and price risk of vegetables can be partially hedged;3) Different vegetables are suitable for different types of agricultural insurance programs. Price insurance is suitable for varieties with weak correlation between yield and price, while income insurance is suitable for varieties with strong negative correlation between them;and 4)at a level of 70 to 90 percent, income insurance premiums of tomato, cucumber, bell pepper and cabbage in large and Medium-sized cities are 7.97%~21.08%, 4.03%~14.41%, 3.90%~13.04% and 1.45%~9.32%, respectively.