中文摘要：

在竞争性的B2B电子商务网站这一市场中，用户转移成本及网络外部性的存在会阻碍用户转向市场后人者，从而给市场先入者带来用户规模优势，而IT成本下降可以给后入者带来成本优势，在这些因素交互影响的市场环境下，先入者和后入者应采取何种IT投资策略以保持竞争优势是一重要问题。针对上述问题，通过综合考虑IT成本下降、用户转移成本及网络外部性等因素，构建了一个序贯进入的、两寡头垄断的B2B电子商务网站的IT投资决策模型，探讨了IT成本下降、用户转移成本及网络外部性等参数变化对B2B电子商务网站IT投资决策的影响。研究结果表明，随着IT成本下降，当用户具有高转移成本时，先入者可采取进攻性的、增加投资的策略；反之，当用户具有低转移成本时，后人者则可采取进攻性的、增加投资的策略，并且能够提供更高质量的网站，获得相对于先入者更高的市场份额；当网络外部性增强时，先入者则可采取进攻性的、增加投资的策略，而后入者只能采取防守性的、减少投资的策略。

英文摘要：

In the competitive market of B2B E-commerce website, as user switching costs and network ex- ternalities could prevent users to switch to later entrant, the earlier entrant has the advantage to build and retain its market share. However, the declining cost of information technology （IT） over time provides the later entrant a cost advantage. In order to maintain competitive advantage, what should the early and late entrant＇s investment strategies be in the presence of user switching costs, network externalities, and decli-ning IT cost？ To analyze this question, considering these three ~actors, information investment strategy model of a duopoly with sequentia entry 1 is developed and the impact of these three factors on IT invest- ment strategy is discussed. The results show that, with the declining IT cost, the early entrant may in- crease its investment in quality, adopting an aggressive investment strategy when switching costs are high. Otherwise, the later entrant may increase its investment in quality, adopting an aggressive investment strategy, and could of{er a higher--quality system and capture a higher market share when switching costs are low. With the enhancement of network externality, the early entrant may increase its investment in quality, adopting an aggressive investment strategy, the later entrant may decrease its investment in quali- ty, adopting a defensive investment strategy.