臺灣高麗菜需求彈性之估計：地理氣候資訊之應用

Estimating the Elasticity of Demand of Cabbage: An Application of Geographical Climate Information

臺灣蔬菜價格常因氣候變化而有巨大的變動，其中高麗菜價格與氣候因子更存在極大關聯。本文以高麗菜各主要產地氣象資料作為估計需求彈性之工具變數，實證結果顯示高麗菜需求彈性介於0.53與0.61之間，並以此彈性進一步評估過去重大氣象事件，如莫拉克颱風及霸王級寒流對消費者福利之影響。此外，高麗菜需求彈性大小受估計期間長短影響，由過去近20年彈性變化顯示，2009年及2013到2015年期間高麗菜價格需求彈性相對較大。需求彈性在2009年期間較大，可能受莫拉克颱風所影響，而臺北農產運銷公司的績效制度改變，可能是影響2013到2015年期間高麗菜需求彈性較大的因素之一。長期而言，需求彈性的改變可能代表消費者面對高麗菜價格大幅波動時，消費偏好的行為調整。

In Taiwan, the price of vegetable often moves closely with fluctuations in weather, especially the cabbage prices. This study estimates the elasticity of demand for cabbages using meteorological data in the main production areas as instrumental variables. Our empirical results indicate that cabbages' elasticities of demand are ranged from 0.53 to 0.61. We also assess the impact of the historical climate events including Typhoon Morakot in 2009, and extreme cold weather in 2016 on consumer surplus. Moreover, the cabbage's elasticities of demand are varied by the length of estimated period. For the past 20 years, we find that the elasticity in 2009, and 2013-2015 are particularly larger than other periods. Typhoon Morakot probably contributes to higher cabbage's elasticity of demand in 2009, while the reason behind the greater elasticities observed over the three-year period from 2013 to 2015 may be the new incentive scheme implemented by the company in charge of auction.