垄断竞争教材.ppt

第12章 垄断竞争 12.2 有差别产品的竞争 * * 对于任何市场而言，所要提出的第一个问题是市场上有多少家企业？——一家企业、几家企业、许多企业 如果有许多企业，我们就要提出第二个问题是企业出售的是相同产品还是有差别的产品？ 需要说明的是，由于现实绝不像理论这样界限分明，在某些情况下，你会发现，很难用某种结构来描述一个市场。比如约有10多家汽车公司在中国出售汽车，那么汽车市场是寡头垄断呢，还是更接近于垄断竞争？答案是有争议的。 此外，也没有一种确切的方法可以确定什么时候产品是有差别的，而什么时候又是相同的。比如不同品牌的牛奶实际上是相同的吗？答案也是有争议的。这些都需要根据实际经济情况进行相应的分析。 For monopolistic competition, free entry/exit drives profits to zero in the long run. In contrast, barriers to entry prevent the monopolist’s profits from being driven to zero. A monopoly is the sole seller of a product with no close substitutes. In contrast, the monopolistic competitor sells a product with many close substitutes. As a result, demand for the monopolist’s product is less elastic than demand for the monopolistic competitor’s product. * * 由于垄断竞争企业出售的产品是有差别的，所以其面临的需求曲线是向右下方倾斜的。换言之，它不是价格的接受者，而在一定程度上是价格的制定者。 垄断竞争企业遵循垄断者的利润最大化规律：它选择边际收益等于边际成本的产量，然后用其需求曲线找出它可以出售的价格。 The graphical analysis of the monopolistically competitive firm’s output, price, and profits/losses is very similar to that of the monopoly firm. One subtle difference is that the demand curve (and MR curve) facing the monopolistically competitive firm is likely to be flatter than the demand curve facing the monopolist, as the monopolistic competitor faces competition from other firms selling similar products. * * 对于垄断竞争企业而言，一旦进入和退出使得经济利润为零，需求曲线与长期平均成本曲线就必定相切。在这个切点时，边际收益等于边际成本，因而实现了最大化利润为0. 垄断竞争市场上长期均衡有两个特点：一是与垄断市场一样，价格大于边际成本（利润最大化和向右下方倾斜的需求曲线）；二是与竞争市场一样，价格等于平均总成本（自由进入和退出市场使经济利润为零）。 The level of output that minimizes ATC is greater than the output that maximizes the monopolistic competitor’s profits. Hence, we say the monopolistic competitor operates with excess capacity. (More on this topic on the next slide.) * * Due to the markup of price over marginal cost, the market output under monopolistic competition will be smaller than the socially efficient output, as we discuss on the following slide. * * The problem facing policymakers here is similar to the prob