《Chapter17.ppt

第十七章 垄断竞争 Monopolistic Competition 不完全竞争市场的类型Types of Imperfectly Competitive Markets 垄断竞争Monopolistic Competition 许多企业出售类似但不相同的产品 Many firms selling products that are similar but not identical. 寡头Oligopoly 只有少数卖主，每一个提供类似的或相同的产品 Only a few sellers, each offering a similar or identical product to the others. 垄断竞争Monopolistic Competition 市场具有某些竞争的特性也具有某些垄断的特性 Markets that have some features of competition and some features of monopoly. 垄断竞争的特征Attributes of Monopolistic Competition 许多卖者 Many sellers 产品差别 Product differentiation 自由进入和退出 Free entry and exit 许多卖者Many Sellers 有许多企业争夺同样的顾客群体There are many firms competing for the same group of customers. 举例：书籍、 CDs 、电影、电脑游戏、餐馆、钢琴课、点心、家具等Product examples include books, CDs, movies, computer games, restaurants, piano lessons, cookies, furniture, etc. 产品差别Product Differentiation 每一个企业生产的产品至少与其他企业生产的产品略有不同 Each firm produces a product that is at least slightly different from those of other firms. 每个企业不是价格接受者，而是面临一条向右下方倾斜的需求曲线 Rather than being a price taker, each firm faces a downward-sloping demand curve. 自由进入和退出Free Entry or Exit 企业可以没有限制地进入和退出一个市场Firms can enter or exit the market without restriction. 市场上企业的数目要一直调整到经济利润为零时为止 The number of firms in the market adjusts until economic profits are zero. 短期中的垄断竞争企业Monopolistic Competitors in the Short Run... 短期中的垄断竞争企业Monopolistic Competitors in the Short Run... 短期中的垄断竞争企业Monopolistic Competition in the Short Run 短期经济利润鼓励新企业进入市场。这导致： Short-run economic profits encourage new firms to enter the market. This: 增加产品提供的数目 Increases the number of products offered. 减少已在市场中的企业面临的需求 Reduces demand faced by firms already in the market. 已有企业面临的需求曲线向左移动 Incumbent firms’ demand curves shift to the left. 随着已有企业的产品需求的减少，这些企业的利润下降Demand for the incumbent firms’ products fall, and their profits decline. 短期中的垄断竞争企业Monopolistic Competition in the Short Run 短期经济亏损鼓励企业退出市场。这导致： Short-run economic losses encourage firms to exit the market. This: 减少产品提供的数目 Decreases the number of prod