1995 / March

寡占競爭與放寬進口配額的經濟效果：一般均衡分析法
Large Oligopolistic Competition and the Economic Effects of Relaxing Import Quotas: A General Equilibrium Analysis

研究論文 Research Article

梁文榮, 麥朝成
Wen-jung Liang, Chao-cheng Mai

1-26

本文利用Konishi et al. (1990) 的寡占競爭市場一般均衡模型，分析當進口財市揚爲寡占市場，放寬（緊縮）進口配額對社會福利、廠商產量、廠商家數及進口財總需求量與國內進口財總產量的影響效果。我們得到二個主要結果爲：放寬進口配額對社會福利可分爲總需求效果、個別廠商産量效果及直接效果三種，由於對個別廠商產量效果的影響不確定，因此放寬進口配額對社會福利的淨效果並不確定，當進口財廠商間之競爭行爲是策略性互補時，放寬進口配額會提高社會福利水準且會增加個別廠商產量；反之，若爲策略性代替且代替程度夠大時，會使個別廠商産量減少，若再加上負向的個別廠商產量效果夠大凌駕總需求及直接效果時，會使社會福利水準下降。至於對國內進口財總產量的影響，當市場需求彈性夠小使廠商間之競爭行爲是策略性互補時，若再加上代替彈性夠小，放寬進口配額會使國內進口財總產量提高；反之，當市場需求彈性夠大使爲策略性代替且代替程度夠大時，則會使國內進口財總產量減少。

The general equilibrium model developed by Konishi et al. (1990) is adopted by this study to explore the economic effects of relaxing im­port quotas on the social welfare, individual firm's output, number of firms, aggregate demand of importable good, and domestic output of importable good. Two main results are found in this paper. First of all, the welfare effect induced by relaxing quota can be decomposed into three parts: aggregate demand effect, firm's output effect and direct effect. The im­pact of relaxing quota on the net social welfare depends on firm's output effect. Relaxing quota will ilncrease both the social welfare and firm's out­put as the strategic behavior between firms is strategic complementary. In contrast, firm's output will decrease if firms' behavior is significantly strategic substitute. While the level of welfare will be decreased if firm's output effect dominates both the aggregate demand effect and direct effect. Secondly, the impact of relaxing quota on domestic output of importable good is also examined. Relaxing quota will increase domestic output of importable good if firms' behavior is strategic complemen­tary due to the sufficiently small elasticity of market price demand, and the much smaller elasticity of substitution. While the domestic output of importable good will be decreased if firms' behavior is significantly strategic substitute caused by the sufficiently large elasticity of market price demand.

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