台灣非農家計糧食消費與家計糧食安全之分析

An Economic Analysis on Household Food Consumption and Household Food Security in Taiwan

本研究主要目的為分析台灣非農家計糧食消費與糧食安全程度。本研究使用行政院主計總處公布最新的1999年至2013年家庭收支調查原始檔，以及物價統計月報，估計台灣非農家計糧食消費之需求體系，並計算台灣非農家計之糧食支出彈性、所得彈性，以及不同結構家計之糧食等值規模與等值支出，模擬過去各年糧食價格之下，樣本家計糧食之等值支出，再以廣義動差法配適伽瑪分配，計算台灣糧食不安全家計之機率，藉以分析過去我國的家計糧食安全情況。本研究之實證結果顯示，台灣家計在主食品類、副食品及其他類、水果類、蛋與乳製品類支出彈性皆小於1，具有必需品的性質，而外食類的支出彈性則略大於1。在人口變數的部分，若價格與糧食總支出不變，人口數較多的家計偏好購買食材回家烹調，而減少外食類之消費；而家計人口數相同的情況下，家計女性人數的多寡對於主食品類消費的變化並不顯著，但會略為增加副食品及其他類、蛋與奶類、水果類之消費，並且減少外食類的消費。台灣家計基期年平均家計人數為3.36人，等值規模為2.41，而平均糧食等值支出約為67,909元。其中，由實證結果可推測在各類不同結構之家計中，平均而言，獨居老人家計、老年人帶兒少家計，以及與老年人同住的單親家計，其家計糧食安全水準較低。另外，本研究透過實證模擬結果可知，台灣在 2001年，以及 2008年至 2010年間，家計糧食安全水準較低，並使糧食不安全的家計比例急遽增加；相對而言，2004年、2012年與 2013年，台灣糧食不安全家計比例較低，表示這三年家計糧食安全水準相對較好。

This study analyzes the status of non-agricultural household food consumption and food security. The raw data of Family Income and Expense Survey and Price Statistics Monthly conducted by the Executive Yuan for years 1990-2013 are used to estimate the demand system of non-agricultural food expenses. The expense elasticity, income elasticity, equivalence scale, and expense of non-agricultural food are calculated for distinct household structures. Given the food price of the past years, the equivalent expenses of the sampled household food are estimated. By using the generalized method of moments with Gamma distribution, the probability of the food-insecure household is calculated and used for analyzing the status of the food security in Taiwan. The results show that the expense elasticities of the non-staple food, staple food, fruits, eggs, and dairy are less than one, matching the feature of necessity. By contrast, the elasticities of the take-out food are slightly larger than one. Regarding the price elasticity, the self-price elasticities of all the analyzed items are negative; especially the take-out food is the most sensitive. Given the same price and food expense, the households with more population prefer cooking at home and reducing the expenses on take-out food. Given the household population, the number of female members is not significantly correlated to the change of expenses on staple food, but is slightly correlated to the non-staple food, fruits, eggs, and dairy in a positive manner. The average population of household in Taiwan is estimated to be 3.36, the equivalence scale is 2.41, and the average food expenses is NT$ 67,909. The results also show that the household of the elderly, the children raised by the elderly, and the single-parent family with the elderly has a lower utility in food than other households. In addition, the study also shows that the food security of Taiwan is lower for years 2001 and 2008-2010 and the ratio of the food-insecure households significantly increases. On the contrary, the ratios of the food-insecure households for years 2004, 2012, and 2013 are lower, indicating a better food security level.