基于半参数Copula方法的蔬菜收入保险定价研究
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摘要
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.
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.
引文
[1]晁娜娜,胡林轩,杨汭华,等.中美棉花保险政策的对比研究[J].农业现代化研究,2018,39(1):71-79.Chao N N,Hu L X,Yang R H,et al.Comparison of cotton insurance policy between the US and China[J].Research of Agricultural Modernization,2018,39(1):71-79.
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[4]王克,张峭,肖宇谷,等.农产品价格指数保险的可行性[J].保险研究,2014,35(1):40-45.Wang K,Zhang Q,Xiao Y G,et al.The feasibility of farm produce price index insurance[J].Insurance Studies,2014,35(1):40-45.
[5]谢凤杰,宋宝辉,吴东立.WTO框架下粮食价格保险政策归属及其改进[J].农业现代化研究,2017,38(2):212-218.Xie F J,Song B H,Wu D L.Analysis of China’s crop target price insurance policy under WTO box classification rules[J].Research of Agricultural Modernization,2017,38(2):212-218.
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[7]Wonho Chung.Analysis of social welfare effects of crop revenue insurance[J].Journal of Rural Development.2014,37(4):75-95.
[8]谢凤杰,吴东立,赵思喆.基于Copula方法的大豆收入保险费率测定:理论与实证[J].农业技术经济,2017,36(2):111-121.Xie F J,Wu D L,Zhao S Z.Determining the premium rate of soybean income based on Copula method:Theory and evidence[J].Journal of Agrotechnical Economics,2017,36(2):111-121.
[9]王保玲,孙健,江崇光.我国引入农业收入保险的经济效应研究[J].保险研究,2017,38(3):71-89.Wang B L,Sun J,Jiang C G.Research on the economic effect of introducing agricultural income insurance in China[J].Insurance Studies,2017,38(3):71-89.
[10]冯文丽,郭亚慧.基于Copula方法的河北省玉米收入保险费率测算[J].保险研究,2017,38(8):19-28.Feng W L,Guo Y H.Calculation of corn revenue insurance pricing in Hebei Province based on Copula method[J].Insurance Studies,2017,38(8):19-28.
[11]晁娜娜,杨汭华,罗少凡.基于Copula模型的棉花收入保险费率测算研究[J].统计研究,2017,34(8):92-99.Chao N N,Yang R H,Luo S F.A study on estimation of premium for cotton revenue insurance based on clayton Copula function[J].Statistical Research,2017,34(8):92-99.
[12]刘素春,刘亚文.农产品收入保险及其定价研究--以山东省苹果为例[J].中国软科学,2018,33(9):185-192.Liu S C,Liu Y W.The analysis of the crop revenue insurance and pricing:On apple industry in Shandong Province[J].China Soft Science,2018,33(9):185-192.
[13]徐婷婷,孙蓉,崔微微.经济作物收入保险及其定价研究--以陕西苹果为例[J].保险研究,2017,38(11):33-43.Xu T T,Sun R,Cui W W.Analysis of the cash crop revenue insurance and its pricing-Take Shaanxi apples as an example[J].Insurance Studies,2017,38(11):33-43.
[14]Sklar A.Distribution functions in n dimensions and their margins[J].Statistics Publications,University of Paris,1959,8:229-231
[15]Cole J B,Gibson R.Analysis and feasibility of crop revenue insurance in China[J].Agriculture and Agricultural Science Procedia,2010,1:136-145.
[16]李辉尚,马娟娟,孔繁涛,等.我国蔬菜价格保险政策面临的问题与对策研究[J].江苏农业科学,2017,45(4):279-282.Li H S,M J J,Kong F T,et al.Study on the problems and countermeasures of vegetable price insurance policy in China[J].Jiangsu Agricultural Sciences,2017,45(4):279-282.
[2]庹国柱,朱俊生.论收入保险对完善农产品价格形成机制改革的重要性[J].保险研究,2016,37(6):3-8.Tuo G Z,Zhu J S.Revenue insurance:An important means to perfect the farm produce price formation mechanism reform[J].Insurance Studies,2016,37(6):3-8.
[3]张雯丽,龙文军.蔬菜价格保险和生产保险的探索与思考[J].农业经济问题,2014,35(1):66-71.Zhang W L,Long W J.Exploration and conception about production insurance and price insurance of vegetable[J].Issues in Agricultural Economy,2014,35(1):66-71.
[4]王克,张峭,肖宇谷,等.农产品价格指数保险的可行性[J].保险研究,2014,35(1):40-45.Wang K,Zhang Q,Xiao Y G,et al.The feasibility of farm produce price index insurance[J].Insurance Studies,2014,35(1):40-45.
[5]谢凤杰,宋宝辉,吴东立.WTO框架下粮食价格保险政策归属及其改进[J].农业现代化研究,2017,38(2):212-218.Xie F J,Song B H,Wu D L.Analysis of China’s crop target price insurance policy under WTO box classification rules[J].Research of Agricultural Modernization,2017,38(2):212-218.
[6]Goodwin B K,Hungerford A.Copula-based models of systemic risk in U.S.agriculture:Implications for crop insurance and reinsurance contracts[J].American Journal of Agricultural Economics,2015,97(3):879-896.
[7]Wonho Chung.Analysis of social welfare effects of crop revenue insurance[J].Journal of Rural Development.2014,37(4):75-95.
[8]谢凤杰,吴东立,赵思喆.基于Copula方法的大豆收入保险费率测定:理论与实证[J].农业技术经济,2017,36(2):111-121.Xie F J,Wu D L,Zhao S Z.Determining the premium rate of soybean income based on Copula method:Theory and evidence[J].Journal of Agrotechnical Economics,2017,36(2):111-121.
[9]王保玲,孙健,江崇光.我国引入农业收入保险的经济效应研究[J].保险研究,2017,38(3):71-89.Wang B L,Sun J,Jiang C G.Research on the economic effect of introducing agricultural income insurance in China[J].Insurance Studies,2017,38(3):71-89.
[10]冯文丽,郭亚慧.基于Copula方法的河北省玉米收入保险费率测算[J].保险研究,2017,38(8):19-28.Feng W L,Guo Y H.Calculation of corn revenue insurance pricing in Hebei Province based on Copula method[J].Insurance Studies,2017,38(8):19-28.
[11]晁娜娜,杨汭华,罗少凡.基于Copula模型的棉花收入保险费率测算研究[J].统计研究,2017,34(8):92-99.Chao N N,Yang R H,Luo S F.A study on estimation of premium for cotton revenue insurance based on clayton Copula function[J].Statistical Research,2017,34(8):92-99.
[12]刘素春,刘亚文.农产品收入保险及其定价研究--以山东省苹果为例[J].中国软科学,2018,33(9):185-192.Liu S C,Liu Y W.The analysis of the crop revenue insurance and pricing:On apple industry in Shandong Province[J].China Soft Science,2018,33(9):185-192.
[13]徐婷婷,孙蓉,崔微微.经济作物收入保险及其定价研究--以陕西苹果为例[J].保险研究,2017,38(11):33-43.Xu T T,Sun R,Cui W W.Analysis of the cash crop revenue insurance and its pricing-Take Shaanxi apples as an example[J].Insurance Studies,2017,38(11):33-43.
[14]Sklar A.Distribution functions in n dimensions and their margins[J].Statistics Publications,University of Paris,1959,8:229-231
[15]Cole J B,Gibson R.Analysis and feasibility of crop revenue insurance in China[J].Agriculture and Agricultural Science Procedia,2010,1:136-145.
[16]李辉尚,马娟娟,孔繁涛,等.我国蔬菜价格保险政策面临的问题与对策研究[J].江苏农业科学,2017,45(4):279-282.Li H S,M J J,Kong F T,et al.Study on the problems and countermeasures of vegetable price insurance policy in China[J].Jiangsu Agricultural Sciences,2017,45(4):279-282.