一种农户与经销商合作的市场风险分担模型

Stability Research for Cooperation Between Farmers and Dealers in China:An Analysis of Marketing Risks Sharing

研究面临市场风险时,何种风险分担机制能更有效提升农户与经销商合作的稳定性。首先,市场行情差时,经销商不履行已签协议的背叛行为,本质是合作协议中没有合理的风险分担约定,或约定不合理。只有当违约远期回报大于当期履约收益时,参与者才有背叛的动力,现有常见的约定收购价格上下限作法,未对合作方的远期回报作精细和理性计算,易于导致违约发生。其次,依据合作博弈中稳定性及夏普利值的成本分担原理,建立了由一个经销商和多个农户构成的多人合作博弈模型,并以此为基础推导核的解空间及以资源禀赋多寡为加权值的风险分担公理值。讨论了特定管理背景下加权夏普利值与核稳定的影响因素与主要作用机理。本文所创立的风险分担理论框架与分析模型,已能够对微观农户合作进行风险分担具体计算和分析,后续无论从宏观角度讨论市场价格波动、还是微观角度研究个体风险偏好,都可以此(或至少以此路径)为基础。

During the research of Chinese vegetable industry and National Science Foundation project of cooperative behaviors between farmers and deals,it is found that for fresh produce industry in some developing nations,there exists a critical problem:Price fluctuates sharply and usually with dealers drop out of the chain letting all the risk to farmers.Different to developed nations,farmers in these developing nations have different risk appetite and constraints.But there is the same thing for all situations,the only reason for any players to drop out is that they don't have or they don't think they have a reasonable benefits(or risk)share.So that in fresh vegetable industry,risk sharing mechanism which could consolidate the cooperation stability between farmers and dealers facing price fluctuations has been discussed.In this paper,firstly the betray behaviors disobeying signed contracts when in a bad marketing,actually lies in the shortage of realistic risk sharing mechanism,or which is unreasonable.It is believed that only rewards when choosing to betray is larger than that of perform,and it could be seen that the simple and rough contract having a fixed lower and upper purchasing price is vulnerable to fail without precise and rational calculations for future rewards.Secondly,based on the stability and Shapley value theory in Cooperative Game,a one dealer and many farmers group is developed into a n-person cooperative game model.The model followed by Sexton(1986)and with more specific description on Chinese farmer risk appetite and constraints which will be much closer to reality than Others.A matlab based analysis has also been done to find the objective function and constraint character.Resolutions for core and weighted Shapley value considering each partner's resources are also discussed.At last,primary influential factors and mechanisms for cooperative stability and weighted Shapley value are discussed,together with practical policy enlightenment ensuring contract stability for both sides.It is found that currently in Chinese vegetable,the most important promotional factor is the risk sharing proportion rather than the introduction of social responsibility,which hints that when facing massive vegetable unmarketable,more efforts should be put on consumers or farmers,least the dealers.This will be beneficial to risk sharing research in farmers especially for fresh produce area.On one side it can be used to analyze risk appetite and price fluctuation in risk sharing from macro level as policy hints;on the other side,it also can be used as a micro analysis tool for specific cooperation on a specific risk sharing calculation.