傾向分數配對法於有機農法經濟結果評估之應用

An Application of Propensity Score Matching Method on the Evaluation of Economic Outcomes of Organic Farming

本文以施行有機與慣行農法之經濟表現差異為主要研究重點，並利用傾向分數配對法修正技術採用行為之內生性問題，以評估採用有機農法對於農民所造成之經濟影響。本研究結果顯示，傾向分數配對法確實能夠有效消除有機與慣行農民原本存在之變項分配差異。此外，本研究發現富里鄉之有機稻米與一般稻米並未存在足夠價差以彌補產量之下降，以致採用有機農法對稻農造成不利之經濟影響。依此，除了提供補助，政府若能責成相關研究單位或農改場找出有效的有機生產方式或田間管理模式以提升有機稻米的產量，亦為有利於有機農法推廣之政策方向之一。 This study examines the difference in the economic performance between organic farming and conventional farming in Fuli, so as to evaluate the economic effect of the government's policy in promoting this environmentallyfriendly farming practice. Based on our analysis, concrete and practical policy recommendations are made for the extension of organic farming. Methodologically speaking, the endogeneity problem of technology adoption leading to biased estimates is a major concern when comparing the economic outcomes between the technology adopters and non-adopters. This study thus applies the propensity score matching method to correct for the endogeneity problem. It is found that the original differences, in kurtosis and peak of the distributions of organic and conventional farming, are eliminated by propensity score matching. The result is further confirmed by the Wilcoxon signed rank test. Investigation of the economic outcomes of organic farming suggests the margin between the two types of rice cannot sufficiently compensate for the reduction in the output level of organic rice, which thus leads to some adverse economic impacts. Policy options that the authorities can take to provide economic incentives to organic farming, such as subsidy and efficient modes of production or field management, are promising directions for the extension of organic farming in Taiwan.