【作者】 陈耀刚；

【导师】 姜彦福；

【作者基本信息】 清华大学 ， 技术经济及管理， 2003， 博士

【摘要】 经过几年的曲折发展，中国的互联网商务已经逐渐成为重要的商务手段和经济现象。然而，国内对于互联网商务比较规范的理论和经验研究都还很少。本文尝试用经济学相关理论分析互联网商务的本质，通过实地调研了解中国互联网商务的发展和竞争现状，并用理论模型解释实践中的重要现象。本文从卖方、买方和中介方等互联网商务参与主体的角度出发，研究了它们各自的参与决策及它们之间的竞争和博弈关系。我们发现，尽管互联网商务具有一些新的特点，但是它在很长时间内仍将是传统商务模式的有益补充。传统经济理论仍然能够较好地解释其中现象并指导实践，互联网商务企业仍然广泛采用了传统市场中的竞争手段和竞争策略。文章的主要结论和创新点包括：第一，基于卖方完全信息动态博弈模型和买方购买决策模型，分别解释了卖方和买方参与互联网商务的决策过程和影响因素。阐明“电子商务替代传统商务”具有片面性，电子商务在很长时间内仍将是传统商务方式的补充，而且传统商务方式和电子商务有融合的趋势。第二，对123家网上网下企业3类产品的销售价格进行了实地调查，并建立Salop-Hotelling“环湖孤岛”综合模型对经验研究结果进行解释。调研结果表明中国目前的互联网商务市场中也没有出现明显的Bertrand竞争的现象，但不同类型商品的竞争特征确有不同：各种商品的网上价格均有明显的扩散现象；但是，手机网上价格偏高、价格扩散大；图书网上价格明显低于网下、价格扩散较小；IP电话卡网上价格偏低、价格扩散最小。环湖孤岛模型证明差别化定位是网络零售商之间缓解价格竞争从而产生价格扩散的重要原因。互联网在创造新市场的同时，也会对不同定位、不同行业的传统厂商产生不同程度的冲击，但低价格并非互联网商务夺取传统厂商市场份额的必要条件。第三，较为系统地阐述了互联网商务方式并不一定会减少信息不对称，并通过一个逆向选择模型，解释了互联网降低卖方交易成本而导致卖方过度涌入，以至出现严重逆向选择的现象。第四，通过建立一个存在买方、卖方和中介方的微观模型，说明在互联网商务环境下，中介仍然有其存在的必要性和必然性，有效率的互联网中介能够从多方面促进互联网商务的发展。更多还原

【Abstract】 After a flexuous development for several years, Internet Commerce gradually becomes an important commerce tool and a kind of economic phenomena in China. However, in China, there is strongly lack of theoretical and empirical studies done well in this field. This thesis tries to reveal the economic features of Internet Commerce using related economic theories, and understand the development and competitive behaviors of Internet Commerce in China through a field survey, as well as explain some important phenomena based on theoretical models.From the angle of different parties of Internet Commerce, namely the seller, buyer and intermediary, the entry decision of each party and the competitive relationship are studied. It is demonstrated that although Internet Commerce really has some new features, it will still be in the complementary position of the traditional commerce in the future. The traditional economic theories can still explain the phenomena of Internet Commerce and instruct the practice well, and the Internet companies still take the competitive strategies and tools used commonly in the traditional market. The main conclusion and contributions are as follows:Firstly, based on a model of dynamic game with perfect information and a model of purchase decision, the decision process and influence factors for seller and buyer are discussed respectively. It is shown that the view of "The traditional commerce will be replaced by e-commerce" is incomplete; e-commerce will be the complement of the traditional commerce, and the convergence of the traditional commerce and e-commerce will be a trend.Secondly, after a field survey of three types products aimed to 123 online and traditional retailers, a model based on the Salop (1979) and Hotelling (1929), named "circular city and isolated island" model, is built to explain the empirical results. The survey results show that there is no obvious Bertrand competition in current Internet Commerce market of China. However, the competitive characteristics of different kinds of products are not the same. Although there is obvious online price dispersion <WP=6>for each product, the online price level and price dispersion of the mobile phones are higher than those of the traditional market; the online price level of the books is significantly lower and the price dispersion is lower; the online price level of the IP card is slightly lower, and the price dispersion is the lowest among this three types of products. The essential reason for the price dispersion in the Internet market is the online retailers’ differentiation strategy, by which the price competition can be alleviated, is demonstrated in the "circular city and isolated island" model. With the new market creation, Internet Commerce can also impact on traditional companies in different industries and with different product positions, but then the low price is not the necessary condition for online companies to erode the market share of the traditional companies.Thirdly, it is elucidated that Internet Commerce does not necessarily reduce the information asymmetry. Through an adverse selection model, the phenomenon that the reduced transaction cost in Internet Commerce induces overmuch seller in the market and results in serious adverse selection is demonstrated.Fourthly, through a microeconomic model with the buyer, seller and intermediary, it is argued that the intermediaries still could and should exist in Internet Commerce environment, and the efficient Internet intermediaries can facilitate the development of Internet Commerce from multiple aspects.更多还原