曼昆经济学Cha.ppt

Monopoly 垄断 Chapter 15 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Monopoly 垄断 While a competitive firm is a price taker, a monopoly firm is a price maker. 竞争企业是价格接受者，而垄断企 业是价格制定者。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Monopoly 垄断 uA firm is considered a monopoly if . . . it is the sole seller of its product. its product does not have close substitutes. 如果一个企业是其产品唯一的卖者，而 且如果其产品并没有相近的替代品，这 个企业就是垄断者。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Why Monopolies Arise 为什么会产生垄断 The fundamental cause of monopoly is barriers to entry. 垄断的基本原因是进入障碍。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Why Monopolies Arise Barriers to entry have three sources: uOwnership of a key resource. uThe government gives a single firm the exclusive right to produce some good. uCosts of production make a single producer more efficient than a large number of producers. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 为什么会产生垄断 进入障碍有三个主要来源: u关键资源由一家企业拥有。 u政府给予一个企业排他性地生产某种产品 或劳务的权利。 u生产成本使一个生产者比大量生产者更有 效率。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Monopoly Resources Although exclusive ownership of a key resource is a potential source of monopoly, in practice monopolies rarely arise for this reason. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 垄断资源 虽然关键资源的排他性所有权是垄断 的潜在原因，但实际上垄断很少产生 于这种原因。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Government-Created Monopolies Governments may restrict entry by giving a single firm the exclusive right to sell a particular good in certain markets. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 政府制造的垄断 政府给予一个企业排他性地出售某种 物品或劳务的权利，限制其他企业进 入市场，从而造成垄断。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Government-Created Monopolies 政府制造的垄断 Patent and copyright laws are two important examples of how government creates a monopoly to serve the public interest. 专利和 版权 是政府如何为公共利益制造垄断 的两个重要例子。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Natural Monopolies 自然垄断 An industry is a natural monopoly when a single firm can supply a good or service to an entire market at a smaller cost than could two or more firms. 当一个企业能以低于两个或更多企业的成本为整个市 场供给一种物品或劳务时，这个产业就是自然垄断。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Natural Monopolies 自然垄断 A natural monopoly arises when there are economies of scale over the relevant range of output. 当相关产量范围内存在规模经济时，自 然垄断就产生了。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Figure 1 Economies of Scale as a Cause of Monopoly 作为垄断原因的规模经济 Average total cost Quantity of Output 产量 Cost 成本 0 平均总成本 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. HOW MONOPOLIES MAKE PRODUCTION AND PRICING DECISIONS uMonopoly versus Competition Monopoly Is the sole producer Faces a downward-sloping demand curve Is a price maker Reduces price to increase sales Competitive Firm Is one of many producers Faces a horizontal demand curve Is a price taker Sells as much or as little at same price Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 垄断者如何作出生产与定价决策 u垄断与竞争 垄断 市场上唯一卖者 其需求曲线是向右下方倾斜的 价格制定者 降低价格才能提高销量 竞争企业 是很多生产者当中的一个 其需求曲线是水平的 是价格接受者 在相同价格下想卖多少就卖多少 Figure 2 Demand Curves for Competitive and Monopoly Firms Quantity of Output Demand (a) A Competitive Firm s Demand Curve(b) A Monopolists Demand Curve 0 Price Quantity of Output0 Price Demand Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 产量 需求 (a) 一家竞争企业的 需求曲线 (b) 一家垄断企业的 需求曲线 0 价格 0产量 价格 需求 图2. 竞争与垄断企业的需求曲线 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. A Monopolys Revenue 垄断者的收益 uTotal Revenue 总收益 P x Q = TR uAverage Revenue 平均收益 TR/Q = AR = P uMarginal Revenue 边际收益 DTR/DQ = MR Table 1 A Monopolys Total, Average, and Marginal Revenue Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 表1. 垄断者的总收益、平均收益和边际收益 产量 (Q) 价格 (P) 总收益 (TR=PxQ) 平均收益 (AR=TR/Q) 边际收益 (MR= ) 0$11.00$0.00 1$10.00$10.00$10.00$10.00 2$9.00$18.00$9.00$8.00 3$8.00$24.00$8.00$6.00 4$7.00$28.00$7.00$4.00 5$6.00$30.00$6.00$2.00 6$5.00$30.00$5.00$0.00 7$4.00$28.00$4.00-$2.00 8$3.00$24.00$3.00-$4.00 QTRDD/ Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. A Monopolys Marginal Revenue A monopolists marginal revenue is always less than the price of its good. uThe demand curve is downward sloping. uWhen a monopoly drops the price to sell one more unit, the revenue received from previously sold units also decreases. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 垄断者的边际收益 垄断者的边际收益总是小于其物品的 价格。 u需求曲线是向下倾斜的。 u当垄断者降低价格增加一个单位销量时 ，从以前的产品销售中得到的收益也减 少。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. A Monopolys Marginal Revenue When a monopoly increases the amount it sells, it has two effects on total revenue (P x Q). uThe output effectmore output is sold, so Q is higher. uThe price effectprice falls, so P is lower. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 垄断者的边际收益 当垄断者增加它的销量时，这对总 收益 (P x Q)有两种效应： u产量效应销售的产品更多，因此Q 增加。 u价格效应价格下降，因此P降低。 Figure 3 Demand and Marginal Revenue Curves for a Monopoly 垄断者的需求与边际收益曲线 Quantity of Water 水的数量 Price 价格 $11 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 -4 12345678 Marginal revenue Demand (average revenue) 边际收益 需求（平均收益） Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Profit Maximization of a Monopoly uA monopoly maximizes profit by producing the quantity at which marginal revenue equals marginal cost. uIt then uses the demand curve to find the price that will induce consumers to buy that quantity. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 垄断企业的利润最大化 u垄断者的利润最大化产量是由边际收益 曲线与边际成本曲线的交点决定的。 u垄断者利用需求曲线发现消费者愿意为 垄断者生产的量支付的价格。 Figure 4 Profit Maximization for a Monopoly Copyright 2004 South-Western QuantityQQ0 Costs and Revenue Demand Average total cost Marginal revenue Marginal cost Monopoly price QMAX B 1. The intersection of the marginal-revenue curve and the marginal-cost curve determines the profit-maximizing quantity . . . A 2. . . . and then the demand curve shows the price consistent with this quantity. 图4. 垄断企业的利润最大化 垄断价格 产量QMAX0 成本与 收益 需求 平均总成本 边际收益 边际成本 A 1.边际收益曲线与 边际成本曲线相交， 决定了利润最大化的 产量. B 2. 这时需求曲线表示 价格与这种数量相一致。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Comparing Monopoly and Competition 垄断与竞争比较 uFor a competitive firm, price equals marginal cost. 对于竞争企业，价格等于边际成本。 P = MR = MC uFor a monopoly firm, price exceeds marginal cost. 对于垄断企业，价格大于边际成本。 P MR = MC Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. A Monopolys Profit 垄断者的利润 Profit equals total revenue minus total costs. 利润等于总收益（TR）减去总成本（TC） 利润 Profit = TR - TC Profit = (TR/Q - TC/Q) x Q Profit = (P - ATC) x Q Monopoly profit Figure 5 The Monopolists Profit Quantity0 Costs and Revenue Demand Marginal cost Marginal revenue QMAX BMonopoly price E Average total costD Average total cost C 垄断利润 图5. 垄断者的利润 产量0 成本和收益 需求曲线 边际成本 边际收益曲线 QMAX B垄断价格 E 平均 总成本 D 平均总成本曲线 C Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. The Monopolists Profit 垄断者的利润 The monopolist will receive economic profits as long as price is greater than average total cost. 只要价格比平均总成本高，垄断 者就可以获得经济利润。 Figure 6 The Market for Drugs Copyright 2004 South-Western Quantity0 Costs and Revenue DemandMarginal revenue Price during patent life Monopoly quantity Price after patent expires Marginal cost Competitive quantity Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 图6. 药品市场 成本和收益 专利期内 的价格 专利到期 后的价格 垄断产量 竞争产量 0 产量 需求 边际成本 边际收益 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. The Welfare Cost of Monopoly uIn contrast to a competitive firm, the monopoly charges a price above the marginal cost. uFrom the standpoint of consumers, this high price makes monopoly undesirable. uHowever, from the standpoint of the owners of the firm, the high price makes monopoly very desirable. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 垄断者的福利代价 u与竞争企业相反，垄断企业收取 高于其边际成本的价格。 u从消费者角度看，这种高价格使垄断 是不合意的。 u但是，从企业的所有者的角度看，高 价格使垄断非常合意。 Figure 7 The Efficient Level of Output Copyright 2004 South-Western Quantity0 Price Demand (value to buyers) Marginal cost Value to buyers is greater than cost to seller. Value to buyers is less than cost to seller. Cost to monopolist Cost to monopolist Value to buyers Value to buyers Efficient quantity Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 价格 0 产量 边际成本 需求 (对买者的价值) 有效率产量 垄断者的成本 对买者 的价值 对买者 的价值 垄断者 的成本 对买者的价值大于垄断者的 成本 对买者的价值小于垄断者的 成本 图7. 有效的产量水平 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. The Deadweight Loss Because a monopoly sets its price above marginal cost, it places a wedge between the consumers willingness to pay and the producers cost. uThis wedge causes the quantity sold to fall short of the social optimum. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 无谓损失 由于垄断者通过收取高于边际成本的 价格发挥其市场势力，它就在消费者 的支付意愿和生产者的成本之间打入 一个楔子。 u这个楔子使销售量低于社会最优产量 。 Figure 8 The Inefficiency of Monopoly Quantity0 Price Deadweight loss Demand Marginal revenue Marginal cost Efficient quantity Monopoly price Monopoly quantity 图8. 垄断的无效率 产量0 需求 边际收益 边际成本 垄断价格 无谓损失 有效率产量垄断产量 价格 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. The Inefficiency of Monopoly 垄断的无效率 The monopolist produces less than the socially efficient quantity of output. 垄断者生产的产量小于社会有 效率的产量。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. The Deadweight Loss uThe deadweight loss caused by a monopoly is similar to the deadweight loss caused by a tax. uThe difference between the two cases is that the government gets the revenue from a tax, whereas a private firm gets the monopoly profit. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 无谓损失 u垄断引起的无谓损失类似于税收引起的 无谓损失。 u税收和垄断之间的差别是政府得到了税 收的收入，而私人企业得到了垄断利润 。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Public Policy Toward Monopolies Government responds to the problem of monopoly in one of four ways. uMaking monopolized industries more competitive. uRegulating the behavior of monopolies. uTurning some private monopolies into public enterprises. uDoing nothing at all. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 对垄断的公共政策 政府会以四种方式中的一种对垄断问题 作出反应： u努力使垄断产业更有竞争性 u管制垄断者的行为 u把一些私人垄断变为公共企业 u无所作为 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Increasing Competition with Antitrust Laws uAntitrust laws are a collection of statutes aimed at curbing monopoly power. uAntitrust laws give government various ways to promote competition. uThey allow government to prevent mergers. uThey allow government to break up companies. uThey prevent companies from performing activities which make markets less competitive. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 用反托拉斯法增强竞争 u反托拉斯法是目的在于遏制垄断力量的法律集成 u反托拉斯法给予政府促进竞争的各种方法。 u这些法律允许政府阻止合并。 u这些法律允许政府分拆公司。 u这些法律禁止公司采取使市场竞争减弱的行动。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Increasing Competition with Antitrust Laws uTwo Important Antitrust Laws Sherman Antitrust Act (1890) Reduced the market power of the large and powerful “trusts” of that time period. Clayton Act (1914) Strengthened the governments powers and authorized private lawsuits. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 用反托拉斯法增强竞争 u两个重要的反托拉斯法 谢而曼反托拉斯法 (1890) 减少当时被认为主宰经济的大而强的“托拉 斯”的市场势力。 克莱顿法 (1914) 加强了政府的权利，并使私人对此类诉讼合 法化。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Regulation 管制 Government may regulate the prices that the monopoly charges. 政府管制垄断者收取的价格。 uThe allocation of resources will be efficient if price is set to equal marginal cost. 如果价格等于边际成本，资源配置将是有效率的。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Figure 9 Marginal-Cost Pricing for a Natural Monopoly 自然垄断的边际成本定价 Regulated Price 管制价格 Quantity 产量 0 Loss 损失 Price 价格 Demand 需求 Marginal cost 边际成本曲线 Average total cost 平均总成本曲线Average total cost 平 均 平均总成本 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Regulation 管制 In practice, regulators will allow monopolists to keep some of the benefits from lower costs in the form of higher profit, a practice that requires some departure from marginal-cost pricing. 实际上，管制者允许垄断者从降低成本 中以更高利润的形式得到一些利益，这 种作法要求对边际成本定价的某种背离 。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Public Ownership 公有制 Rather than regulating a natural monopoly that is run by a private firm, the government can run the monopoly itself. (e.g. in the U.S., the government runs the Postal Service). 政府不是管制由私人经营的自然垄断，而是 自己经营自然垄断本身（例如，美国政府经 营邮政服务）。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Doing Nothing 无所作为 Government can do nothing at all if the market failure is deemed small compared to the imperfections of public policies. 如果市场失灵的程度小于公共政策不完善 所引起的政策失灵，政府可以无所作为。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Price Discrimination 价格歧视 Price discrimination is the practice of selling the same good at different prices to different customers, even though the costs for producing for the two customers are the same. 价格歧视是以不同价格向不同消费者出售同 一种物品的作法，尽管对两个消费者的生产 成本是相同的。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. PRICE DISCRIMINATION uPrice discrimination is not possible when a good is sold in a competitive market since there are many firms all selling at the market price. In order to price discriminate, the firm must have some market power. uPerfect Price Discrimination Perfect price discrimination refers to the situation when the monopolist knows exactly the willingness to pay of each customer and can charge each customer a different price. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 价格歧视 u当一种物品在竞争市场上销售时，价格 歧视 是不可能的，这是因为有很多以市 场价格销售同一种物品的企业。 为了做 到价格歧视，企业必须具有一些市场势 力。 u完全价格歧视 完全价格歧视 是指垄断者完全了解每个消 费者的支付意愿，并对每位消费者收取不同 价格的情况。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Price Discrimination 价格歧视 uTwo important effects of price discrimination: 价格歧视带来的两种重要效果： uIt can increase the monopolists profits. 价格歧视能增加垄断者的利润。 uIt can reduce deadweight loss. 价格歧视可能减少无谓损失。 Figure 10 Welfare with and without Price Discrimination Copyright 2004 South-Western Profit (a) Monopolist with Single Price Price 0Quantity Deadweight loss Demand Marginal revenue Consumer surplus Quantity sold Monopoly price Marginal cost Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 无谓损失 消费者剩余 图10. 有无价格歧视时的福利 价格 0数量 利润 需求 边际成本 边际收益 销售量 垄断价格 (a) 单一价格垄断者 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Figure 10 Welfare with and without Price Discrimination 有无价格歧视时的福利 Price 价格 0Quantity 数量 Demand 需求 Marginal cost 边际成本 Quantity sold 销售量 (b) Monopolist with Perfect Price Discrimination 完全价格歧视垄断者 Profit Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Examples of Price Discrimination 价格歧视的例子 uMovie tickets 电影票 uAirline prices 飞机票价 uDiscount coupons 折扣券 uFinancial aid 奖学金 uQuantity discounts 数量折扣 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Conclusion: The Prevalence of Monopoly uHow prevalent are the problems of monopolies? uMonopolies are common. uMost firms have some control over their prices because of differentiated products. uFirms with substantial monopoly power are rare. uFew goods are truly unique. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 结论：垄断者的普遍性 u垄断问题有多普遍? u垄断是常见的。 u许多企业对它们收取的价格都有一些控制 能力，因为它们提供的物品与其它企业提 供的物品并不完全一样。 u有相当大垄断势力的企业是很少见的。 u很少物品真正是独一无二的。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. Summary uA monopoly is a firm that is the sole seller in its market. uIt faces a downward-sloping demand curve for its product. uA monopolys marginal revenue is always below the price of its good. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc. 小结 u垄断者是在其市场上为唯一卖者的 企业。 u垄断者面临的需求曲线是向右下方 倾斜的。 u垄断者的边际收益总是低于其物品 的价格。 Harcourt, Inc. items