蔬菜价格波动背景下生产者种植意愿变化研究——兼论对Logistic模型的重新解读

Study of vegetable growers' behavior in the background of vegetable price volatility and new interpretation of logistic model

首先推敲Logistic模型的应用,在此基础上,总结Logistic模型可以进一步改进的地方。文献中有关Logistic模型回归系数的经济含义解释较为模糊,本研究通过比较解释变量各状态,以研究蔬菜价格波动背景下生产者行为变化影响因素为例,深化Logistic模型回归系数的经济含义。研究发现:若假定有其他经历的菜农在菜价剧烈波动背景下不放弃蔬菜种植的概率是50%,则仅有务农经历的菜农不放弃蔬菜种植的概率为79.18%。同理,假设蔬菜种植非家庭主要收入的菜农不放弃蔬菜种植的概率为50%时,以蔬菜种植为主要收入来源的菜农不放弃蔬菜种植的概率达84.44%。Logistic模型从经验上反应了菜农不放弃蔬菜种植的原因:蔬菜种植是主要收入来源,人生经历单一,务农经历长等。反过来这意味着当蔬菜价格波动剧烈频繁,风险增加时,若有其他可供选择的机会,生产者放弃蔬菜种植的可能性会变大。蔬菜价格波动和供给是相辅相成的关系,保障供给可以稳定蔬菜价格,蔬菜市场风险减小又可以进一步保障供给。

This study reviewed practical applications of binary or multivariate logistic models and also tried to explain economic implication of logistic model coefficients by comparing various statuses of explanatory variables based on characteristics of binary, polytomous and continuous variables. Some of the applications are arguable and should be amended. Specifically,vegetable growers＇ behavior in the background of vegetable price volatility was investigated. Based on the logistic models,the main conclusions are as follows;firstly,when the probability of not giving up cultivating vegetables is assumed to be 50% in background of vegetable price volatility for farmers who has others experiences besides farming, the probability for those who just has farming experience not to give up vegetable cultivation is 79.18%. Similarly,when the probability of not giving up cultivating vegetables is assumed to be 50% for farmers whose main income source is not vegetable cultivation, the probability for those whose main income source is vegetable cultivation not to give up vegetable cultivation is 84.44%. So it is concluded that the farmers whose main income source is vegetable cultivation and main experience is farming are less possible to give up planting vegetables when price is volatile. It implies that when vegetable price is volatile frequently and the uncertainty in vegetable marketincreases,the probability for farmers to give up vegetable cultivation will increase. Vegetable price and supply are related with each other. Ensuring vegetable supplies could stabilize price and vegetable price stabilization could ensure supplies as well.