本文主要是結合空間雙占模型與消費外部性模型，分別討論在產品品質有差異的情況下，消費外部性對廠商的最適均衡策略會有何影響。當消費者具有標新立異特性時，廠商的均衡價格會較高，而當消費者具有從眾性時，廠商則會出現激烈的削價競爭。再者，討論市場存在炫耀性商品的情況下，消費者藉由購買炫耀性商品來展現高所得並且得到更高的社會地位；對於此類型的虛榮消費者，政府一般實行課徵奢侈稅或完全禁止炫耀性商品。研究發現，將此兩種情況分別與自由放任進行比較，社會福利的變動情形會出現完全相反的結果。

This paper is a combination of spatial duopoly model together with consumption externality model. Under the circumstance of heterogeneous products, I will discuss separately the influence of consumption externalities on the optimal equilibrium strategy of the firm. When consumers are characterized with the snob, the equilibrium price tends to be higher; however, consumers are characterized with the conformity, firms will be fierce price competition. Moreover, given the existence of conspicuous goods, consumers purchase a conspicuous good in order to display their relative high income and thereby achieve greater social status. And for this type of conspicuous consumers, the government will generally levy a luxury tax or even prohibit the consumption of the conspicuous good. And finally, by comparing these two cases with the laissez-faire economy, changes in the social welfare are exactly in an opposite direction.

第一章 緒論……………………………………………1
第一節 研究目的與動機………………………………………………………..1
第二節 研究方法與架構………………………………………………………..2
第二章 文獻回顧………………………………………4
第一節 消費外部性與社會福利………………………………………………..4
第二節 防削價競爭均衡………………………………………………………..7
第三章 理論模型………………………………………8
第一節 模型基本假設與設定…………………………………………………..9
第二節 消費者為標新立異下對廠商的影響…………………………………11
第三節 消費者為從眾下對廠商的影響………………………………………18
第四章 社會福利之分析……………………………..23
第五章 結論與未來研究方向………………………..33
第一節 結論……………………………………………………………………33
第二節 未來研究方向…………………………………………………………34
參考文獻………………………………………………35
附錄……………………………………………………37
圖次
圖1. 三種型態之外部性大小………………………………………………………17
圖2. 從眾下之價格空間……………………………………………………………19

中文參考文獻：
1. 李華夏（譯）(2007)，「有閒階級論」，(T. Veblen)，台灣：左岸文化出版社。
2. 邱永和（譯）(2004)，「網路資訊經濟學」，(O. Shy)，台灣：雙葉書廊出版社。
3. 吳志宏(2009)，「你做對廣告了嗎？多元消費外部性市場的廠商最適策略」，國立中山大學經濟學研究所碩士論文。
4. 楊奕農、王鳳生(2003)，「網路外部性下公營事業民營化之福利效果分析」，亞太經濟管理評論，2，21-33。
英文參考文獻：
1. Amaldoss, W. and Jain, S. (2005), “Pricing of Conspicuous Good: A Competitive Analysis of Social Effects,” Journal of Marketing Research, Vol. XLⅡ, pp. 30-42.
2. Bagwell, L. and Bernheim, B.D., (1996) “Veblen effects in a theory of conspicuous consumption,” American Economic Review, Vol. 86, pp. 349-373.
3. Becker, G. (1991), “A note on restaurant pricing and other examples of social influences on prices,” Journal of Political Economy, Vol. 99, pp. 1109-1116.
4. Bernheim, B.D., (1994) “A theory of conformity,” Journal of Political Economy, Vol. 102, pp. 841-877.
5. Corneo, G. and Jeanne, O. (1997), “Conspicuous consumption, snobbism and conformish,” Journal of Public Economics, Vol. 66, pp. 55-71.
6. Economides, N. (1996), “The Economics of Networks,” International Journal of Industrial Organizations, Vol. 14, pp. 673-699.
7. Grilo, I. , Shy, O. and Thisse, J.F. (2001), “Price competition when consumer behavior is characterized by conformity or vanity,” Journal of Public Economics, Vol. 80, pp. 385-408.
8. Hotelling, H. (1929), “Stability in competition,” Economic Journal, Vol. 39, No. 153, pp. 41-57.
9. Katz, M.L. and Shapiro, C. (1985), “Network Externalities, Competition, and Compatibility,” The American Economic Review, Vol. 75, No. 3, pp. 424-440.
10. Morgan, P.B. and Shy, O. (2000), “Undercut-Proof Equilibria,” Retrieved from http://ozshy.50webs.com/conhot71.pdf .