信息不对称、逆向选择和市场均衡

Information Asymmetry, Adverse Selection and Market Equilibrium

几乎所有研究信息不对称与逆向选择问题的文献都隐含着一家厂商在同一时刻只能提供单一质量水平产品的假设。本文在厂商可以同时提供高质量产品和低质量产品的假设基础上，通过建立模型来探讨信息不对称与逆向选择的关系。研究结论表明。当考虑到这一前提条件时，信息不对称所导致的逆向选择程度可能并不像先前的研究者所认为的那么严重，甚至可能不存在。此外，模型也指出，消费者所拥有的财富数量将严重地影响到逆向选择的程度，财富数量与逆向选择的严重程度存在着负相关关系。这个结论可以很好地解释在发展中国家假冒伪劣现象十分普遍的原因。最后，拟以浙江省龙井茶市场为例来验证本文所发展的理论。

There is a common implicit assumption in almost all the literature regarding infor- mation asymmetry and adverse selection that one firm can only supply single quality product.The thesis mainly discusses the relationship between information asymmetry and adverse selection through one model on the assumption that one firm can supply not only high-quality products but also low-quality products.The conclusion indicates that the degree of adverse selection brought about by information asymmetry may be not so serious as mentioned by some researchers,even nonexistent.The model also shows that the wealth owned by consumers will have great effects on the degree of adverse selection and there is negative correlation between the amount of wealth and the degree of adverse selection,which can justify why the phenomenon of counterfeiting is so pop- ular in the developing countries such as China.In the end,the case of Longjing tea in Zhejiang province is cited to support the above conclusion.