仿冒行為的經濟分析

Three Essays on Counterfeiting

蔡明芳(Ming-Fang Tsai)

指導教授 ： 邱俊榮

國立中央大學/管理學院/產業經濟研究所/博士(2008年)

摘要

中文摘要 論文題目：仿冒行為的經濟分析 校所組別：國立中央大學 產業經濟研究所 研究生：蔡明芳 指導教授：邱俊榮 博士 論文提要： 本論文首先利用一垂直差異化模型討論仿冒與政府執法以及本國市場存在仿冒下的進口關稅問題。其次，我們也利用一同時考慮水平異質與垂直差異下的模型來討論，當正版廠商必須同時面對其他正版廠商與仿冒者競爭時，政府取締仿冒的寬嚴程度不一時，消費者購買行為的變化。本論文分別就這三個議題來分析討論，我們得到的結論如下。 （一）在政府取締仿冒的執法政策方面，我們發現只要仿冒有出現的可能，正版廠商的銷售量即可能反而增加。其次，就政府取締仿冒的執法政策而言，我們發現，當政府取締仿冒的執法程度趨於嚴格時，社會福利可能提高或降低；此外，當市場存在仿冒時，政府執法程度趨近完全執法下的社會福利與完全不執法下的社會福利大小不確定；最後，即使取締仿冒的執法成本很高，政府嚴格地取締仿冒仍然可以改善社會福利。 （二）我們也可討論本國市場存在仿冒時，正版品的最適關稅問題。在一外國正版廠商出口至本國，本國市場可能出現仿冒品的模型設定下，本論文討論本國政府如何對外國正版品廠商課徵最適關稅。我們亦考慮此一產品可能存在網路外部性的情況。首先，我們發現，無論網路外部性是否存在，若本國市場存在仿冒的可能，則當獨占正版廠商的生產成本提高時，本國政府會大幅提高關稅。其次，當仿冒存在且產品的網路外部性夠大，則最適進口關稅也可能反而會隨外國廠商的成本增加而提高。上述二結論不同於文獻上一般認為最適關稅應與廠商成本呈反向關係的認知。最後，我們也發現，當本國執法部門取締仿冒的執法程度提高，則外國正版廠商面對的最適進口關稅也會因此提高。 （三）有別於過去仿冒文獻只討論一家正版廠商的仿冒問題，本論文建立一同時考慮水平與垂直異質的寡占模型，來分析市場仿冒活動有無發生下，消費者購買行為的變化。我們發現，當市場上存在仿冒活動時，某一品牌的正版品價格降低，將使得對該品牌忠誠度較高的消費者可能反而會購買仿冒品，但對品牌較無特別偏好者反而可能直接購買正版品。同時，我們也討論了政府取締仿冒活動的寬嚴程度不一對消費者的影響。我們得到的結果如下。第一，對於品牌較無特殊偏好的消費者而言，當政府取締某一產品的仿冒時，原來買該仿冒品的這些消費者可能轉而購買此一正版品或不購買任何產品，但不可能繼續購買此一仿冒品。第二，對原本購買正版品的消費者而言，當政府取締某一仿冒品趨嚴時，可能使得原來購買該正版品的消費者會繼續購買此一正版品，也可能改買另一正版品或不購買任何產品，甚至可能轉而購買另一正版品的仿冒品。

關鍵字

政府執法 ； 關稅 ； 仿冒 ； 水平差異 ； 垂直差異

並列摘要

Abstract
This dissertation discusses the issues on counterfeiting. I discuss the relationships between counterfeiting and enforcement, counterfeiting and tariff and counterfeiting and consumer’s decisions, respectively. I find the following results.

First, I use a vertical product differentiation model to explore the impact of the government’s enforcement on counterfeiting and social welfare. I find that as counterfeiting may occur, sales of the original product could either increase or decrease. The welfare effects of government enforcement are shown as follows. First, a strict enforcement on counterfeiting by government may either increase or decrease welfare. Second, when counterfeiting emerges, welfare under a stricter enforcement is not necessarily larger than that without enforcement. Last, a strict enough enforcement can still improve welfare even if there is a relatively high enforcement cost.

Second, I also introduce counterfeiting into a vertical difference model and concern about the relationship between tariff policy which the home government takes for the original firm and social welfare. I find the following results. First, regardless of the network externality of the product, the optimal tariff will raises as the cost of the foreign firm increases when counterfeiting firms may emerge. Second, when the counterfeiting occurs and network externality of the product is large enough, the optimal tariff will also increase with the cost of the foreign firm. Last, if the foreign firm asks government to take law enforcement, the import tariff of the original will increase instead.

Last, I establish a duopoly model which considers the horizontal differentiation and vertical differentiation simultaneously to investigate the changes in consumer’s purchasing behavior in presence of counterfeiting. We find that as the price of one brand of a genuine product decreases due to the emergence of its counterfeit, the consumers who have a high loyalty to the brand of product could instead purchase the counterfeiting one, but consumers who do not have a strong preference on the brand of product could show their interests in the genuine one. As far as government enforcement is concerned, we find the following interesting results. First, with government enforcement on a particular counterfeit, the consumers who show no strong preference on a particular brand and also originally purchased the counterfeit could instead go to purchase its genuine product or purchase nothing but not possibly continue to purchase the counterfeit. Second, for those consumers who originally purchased a genuine product, a more rigorous government monitoring rate on its counterfeit could lead to three more possibilities: purchase the genuine product of the other brand, purchase nothing or, quite interestingly, purchase the counterfeit of the other brand of genuine product.

並列關鍵字

Enforcement policy ； Tariff ； Counterfeiting ； Horizontal differentiation ； Vertical differentiation

參考文獻

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