本文利用著名的空間競爭模型（Hotelling, 1929）來進行分析。假設在網路交易的過程中消費者必須使用搜尋介面搜尋商品且其對於搜尋介面有一偏好，消費者在考慮商品的價格、平台的水平差異（偏好）與垂直差異（商譽）之後選擇透過哪一個平台完成交易。本文設定廠商提供的搜尋介面具有非敵對性且功能越多、廣度更大的搜尋介面能夠滿足更多消費者的偏好、增加需求，因此廠商除了進行價格競爭之外還會進行研發搜尋介面的競爭。 本文發現商譽較高的平台會收取較高的廣告費、提供較多的研發量，且商譽的差異可能造成商譽高的平台獨占，但是在兩個廠商同時存在的市場結構下，廠商的商譽差異較大卻會使社會福利較大。 本文的主要貢獻：（1）提供一個網路交易平台服務市場的理論模型，這個模型可以分析平台的垂直差異對社會福利的影響。（2）本文所使用的研發概念提供區位選擇行為一個新的詮釋，增加空間競爭模型的應用性。 This article uses the famous spatial competition model (Hotelling, 1929) to carry on the analysis. The assumption is that the consumer must use the searching intermediary to search commodity in the network transaction process also there is preference on the searching intermediary, after consumer considerate the price of commodity, the horizontal difference (preference) and the vertical difference(reputation) which platform chooses penetrates to complete the transaction. This article establishes the searching intermediary where the manufacturer provides to be non-rival with more functions, a searching intermediary with a bigger breadth can satisfy more consumers by chance, and increase the demand, therefore the manufacturer will research and develop a better searching intermediary besides the price competition. This article mainly contributes: 1. This article provides a theoretical model of network platform service which analyzes how the vertical difference of the platform affects the social welfare. 2. This article gives the spatial competition model more applications by giving new annotation to the concept of choice behavior.
