本論文涵蓋兩個議題一為廠商區位決策，一為品質定位選擇。第一個議題建立一個Barbell 模型，在一直線的兩端點有兩個大小相等的市場，兩市場各有 n_A、n_B 家零售商，向上游獨佔的供應商購買產品後再銷售給消費者，兩端市場的零售商除了批發價外還須負擔進貨的運費和固定成本，分別在零售商廠商家數固定及零售商可自由進入市場之下，探討供應商不同訂價策略對其區位及社會福利的影響。本文發現在零售商家數相同(即 n_A = n_B = n )之下，當兩端市場的零售商家數夠多時，若供應商採取單一訂價，則供應商的最適區位為直線中點；若供應商採取差別訂價，則供應商的最適區位為直線上任意點，此外，差別訂價下的總產量及社會福利均大於單一訂價。在允許零售商自由進入市場下，若供應商採取單一訂價，其可以在直線上任一點設廠，而差別訂價時只會在市場的兩端設廠，總產量則會相同，在社會福利方面得到差別訂價可能大於單一訂價，並且不論是單一或差別訂價允許零售商自由進入後，皆可能會讓零售商家數增加。第二個議題則是假設市場上有一既存廠商，原先只生產一種高(低)品質產品，探討若有一新的低(高)品質產品待生產，則是由獨佔的既存廠商同時生產兩種產品，還是雙佔時新進入市場的廠商生產較有誘因。本文得到，不論新的產品為高或低品質，皆是新進入市場的廠商較有誘因生產。

This paper contains two topics. One is the optimal location, the other is quality position of firms. One of the topics extends Barbell model which has the same size’s markets at the end of a straight line’s both side. There are n_A and n_B retailers respectively located on the both side, having to buy the product form the wholesaler then sell to the customers. Additionally, retailers would absorb the transport cost and fixed cost. We discuss how the numbers of retailers affect the wholesaler’s location and after the free entry happened. Given n_A = n_B = n condition, under the uniform pricing, we derive the optimal location would move from any place to 1/2 when the numbers of retailers increase gradually. Under the discriminatory pricing, the optimal location would move from the end of both side to any place when the numbers of retailers increase gradually. Furthermore, the social welfare and total output may higher under the discrimination depend on the numbers of retailers. Then we allow the outside retailers to entry the markets, simply get the familiar results with above. The other topic is we assume that there is a monopolist producing the higher (lower) quality product in the market at first. However, if the new product which is lower (higher) quality appears, should the monopolistc firm simultaneously produce two different quality products or only let the entrant produce the new one? We compare the individual incentives and find no matter what the new product’s quality is, the entrant always has the higher incentive to produce it.

論文審定書.................................................................................................................. i
誌謝................................................................................................................................ ii
中文摘要...................................................................................................................... iii
英文摘要...................................................................................................................... iv
目錄................................................................................................................................ v
圖次............................................................................................................................... vii
第一章 緒論.............................................................................................................. 1
第二章 文獻回顧與研究方法............................................................................. 2
第三章 廠址區位決策模型.................................................................................. 6
3.1 零售商家數固定下，供應商之最適區位與訂價策略........................... 6
3.1.1 單一訂價下的最適區位................................................................................ 7
3.1.2 差別訂價下的最適區位.............................................................................. 15
3.1.3 單一訂價與差別訂價下，社會福利及總產量比較.................................. 22
3.2 允許零售商自由進入市場下，供應商之最適區位與訂價策略........ 26
3.2.1 單一訂價下的最適區位.............................................................................. 26
3.2.2 差別訂價下的最適區位.............................................................................. 27
3.2.3 單一訂價與差別訂價下，社會福利及總產量比較.................................. 29
3.2.4 有無自由進入下，零售商家數比較.......................................................... 30
3.3 小結................................................................................................................ 32
第四章 品質定位選擇模型................................................................................ 33
4.1 既存廠商生產高品質產品......................................................................... 33
4.1.1 既存廠商生產高品質產品.......................................................................... 33
4.1.2 既存廠商生產高低品質產品...................................................................... 34
4.1.3 既存廠商生產高品質產品，新進入廠商生產低品質產品...................... 35
4.1.4 既存廠商生產高品質產品下之誘因比較.................................................. 36
4.1.5 既存廠商生產高品質產品下之福利比較.................................................. 37
4.2 既存廠商生產低品質產品......................................................................... 39
4.2.1 既存廠商生產低品質產品.......................................................................... 39
4.2.2 既存廠商生產低品質產品下之誘因比較.................................................. 39
4.2.3 既存廠商生產低品質產品下之福利比較.................................................. 41
4.3 小結................................................................................................................ 42
第五章 結論............................................................................................................ 43
參考文獻...................................................................................................................... 44
附錄............................................................................................................................... 47

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