15垄断

nullnullChapter 15 MonopolynullIf you own a personal computer, it probably uses some version of Window, the operating system sold by the Microsoft Corporation. When Microsoft first designed Windows many years ago, it applied for and received a copyright from the government. The copyright gives Microsoft the exclusive right to make and sell copies of the Windows operating system. So if a person wants to buy a copy of Windows, he or she has little choice but to give Microsoft the approximately $50 that the firm has decided to charge for its product. Microsoft is said to have a monopoly in the market for Windows. (Mankiw, p313.) nullWhile a competitive firm is a price taker, a monopoly firm is a price maker. A firm is considered a monopoly if… It is the sole seller of its product. Its product does not have a close substitutes. nullThe fundamental cause of monopoly is barriers to entry. A monopoly remains the only seller in its market because other firms cannot enter the market and compete with it. Barriers to entry have three sources: A key resource is owned by a single firm. The government gives a single firm the exclusive right to produce some good. Costs of production make a single producer more efficient than a large number of producers. 15.1 Why monopolies ArisenullAlthough exclusive ownership of a key resource is potential source of monopoly, in practice monopolies rarely arise for this reason. Actual economies are large, and resources are owned by many people. Indeed, because many goods are traded internationally, the natural scope of their markets is often worldwide. There are, therefore, few examples of firms that own a resource for which there are no close substitutes. 15.1.1 Monopoly ResourcesnullA classic example of ownership of a key resource is DeBeers, the South African diamond company. DeBeers controls about 80% of the world’s production of diamonds. Although the firm’s share of the market is not 100%, it is large enough to exert substantial influence over the market price of diamonds. How much market power does DeBeers have? The answer depends in part on whether there are close substitutes for its product. If people view emeralds, rubies, and sapphires as good substitutes for diamonds, then DeBeers has relatively little market power. In this case, any attempt by DeBeers to raise the price of diamonds would cause people to switch to other gemstones. But if people view these other stones as very different from diamonds, then DeBeers can exert substantial influence over the price of its product. Case study: The DeBeers diamond MonopolynullDeBeers pays for large amounts of advertising. At first, this decision might seem surprising. If a monopoly is the sole seller of its product, why does it need to advertise? One goal of the DeBeers ads is to differentiated diamonds from other gems in the minds of consumers. When their slogan tells you that “a diamond is forever,” you are meant to think that the same is not true of emeralds, rubies, and sapphires. If the ads are successful, consumers will view diamonds as unique, rather than as one among many gemstones, and this perception will give DeBeers greater market power.Case study: The DeBeers diamond MonopolynullIn many cases, monopolies arise because the government has given one person or firm the exclusive right to sell some good or service. Sometimes the monopoly arises from the sheer political clout of the would-be monopolist. Kings, for example, once granted exclusive business licenses to their friends and allies. Patent and copyright laws are two important examples of how government creates a monopoly to serve the public interest. When a pharmaceutical company discovers a new drug, it can apply to the government for a patent. If the government deems the drug to be truly original, it approves the patent, which gives the company the exclusive right to manufacture and sell the drug for 20 years. Similarly, a novel of an novelist.15.1.2 Government-Created MonopoliesnullnullAn 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. An example of a natural monopoly is the distribution of water. To provide water to residents of a town, a firm must build a network of pipes throughout the town. If two or more firms were to compete in the provision of this service, each firm would have to pay the fixed cost of building a network. Thus, the average total cost of water is lowest if a single firm serves the entire market. 15.1.3 Natural MonopoliesnullOther examples of natural monopolies: some goods in the economy are excludable but not rival. An example is a bridge used so infrequently that it is never congested. (1)The bridge is excludable because a toll collector can prevent someone from using it. (2)The bridge is not rival because use of the bridge by one person does not diminish the ability of others to use it. Because there is a fixed cost of building the bridge and a negligible marginal cost of additional users, the average total cost of a trip across the bridge falls as the number of trips rises. Hence, the bridge is a natural monopoly. (Mankiw, Principles of Economics(2004),chapter15, p317.) 15.1.3 Natural Monopoliesnull15.2.1 Monopoly 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 Paces a horizontal demand curve Is a price taker Sells as much or as little at same price15.2 How Monopolies Make Production and Pricing DecisionsnullFigure 2 Demand Curves for Competitive and Monopoly FirmsFigure 2 Demand Curves for Competitive and Monopoly FirmsCopyright © 2004 South-WesternQuantity of Output(a) A Competitive Firm’s Demand Curve(b) A Monopolist’s Demand Curve0PriceQuantity of Output0PricenullTotal Revenue P×Q = TR Average Revenue TR/Q = AR = P Marginal Revenue △TR/△Q = MR 15.2.2 A Monopoly’s RevenuenullnullA Monopoly’s Marginal Revenue A monopolist’s marginal revenue is always less than the price of its good. The demand curve is downward sloping. When a monopoly drops the price to sell one more unit, the revenue received from previously sold units also decreases. 15.2.2 A Monopoly’s RevenuenullMarginal Revenue for monopolists is very different from marginal revenue for competitive firms. When a monopoly increases the amount it sells, it has two effects on total revenue (P×Q). The output effect –- more output is sold , so Q is higher. The price effect –- price falls, so P is lower. 15.2.2 A Monopoly’s RevenuenullBecause a competitive firm can sell all it wants at the market price, there is no price effect. When it increases production by 1 unit, it receives the market price for that unit, and it does not receive any less for the units it was already selling. That is, because the competitive firm is a price taker, its marginal revenue equals the price of its good. By contrast, when a monopoly increases production by 1 unit, it must reduce the price it charges for every unit it sells, and this cut in price reduces revenue on the units it was already selling. As a result, a monopoly’s marginal revenue is less than its price. 15.2.2 A Monopoly’s RevenuenullThe Monopolist Maximizing ProfitsWe begin by studying the monopolist’s profit-maximization problem. Let us use p(y) to denote the market inverse demand curve and c(y) to denote the cost function. Let r(y) =p(y)y denote the revenue function of monopolist. The monopolist’s profit-maximization problem then takes the form Max r(y) – c(y) The optimality condition for this problem is straightforward: at the optimal choice of output we must have marginal revenue equal to marginal cost. In terms of algebra, we can write the optimization condition as nullMaximizing ProfitsIn the case of a monopolist, the marginal revenue term is slightly more complicated. If the monopolist decides to increase its output by y, there are two effects on revenues. First it sells more output and receives a revenue of py from that. But second, the monopolist pushes the price down by p and it gets this lower price on all the output it has been selling. Thus the total effect on revenues of changing output by y will be r = p y + y p So that the change in revenue divided by the change in output----the marginal revenue----is nullMaximizing ProfitsWe can also express marginal revenue in terms of elasticity via the formula And write the “marginal revenue equals marginal costs” optimality condition as Since elasticity is naturally negative, we could also write this expression as nullMaximizing Profits From these equations it is easy to see the connection with the competitive case: in the competitive case, the firm faces a flat demand curve----an infinitely elastic demand curve. This means that 1/ |є|= 1/ = 0, so the appropriate version of this equation for a competitive firm is simply price equals marginal cost. nullMaximizing ProfitsNote that a monopolist will never choose to operate where the demand curve is inelastic. For if |є| < 1, then 1/|є| >1, and the marginal revenue is negative, so it can’t possibly equal marginal cost. The meaning of this becomes clear when we think of what is implied by an inelastic demand curve; if |є| < 1, then reducing output will increase revenues, and reducing output must reduce total cost, so profits will necessarily increase. Thus any point where |є| < 1 cannot be a profit maximum for a monopolist, since it could increase its profits by producing less output. It follows that a point that yields maximum profits can only occur where |є|  1. (Hal R. Varian, Intermediate Microeconomics, sixth edition, p420-421.)Figure 3 Demand and Marginal-Revenue Curves for a MonopolyFigure 3 Demand and Marginal-Revenue Curves for a MonopolyCopyright © 2004 South-WesternQuantity of WaterPrice$11109876543210–1–2–3–412345678pMPMRP=MRQMPinullFigure 3 graphs the demand curve and the marginal-revenue curve of a monopoly firm. Theses two curves always start at the same point on the vertical axis because the marginal revenue of the first unit sold equals the price of the good. The monopolist’s marginal revenue is less than the price of the good. Thus, a monopoly’s marginal-revenue curve lies below its demand curve. (Mankiw, third edition, p321.) Marginal revenue can even become negative. Marginal revenue is negative when the price effect on revenue is greater than the output effect. In this case, when the firm produces an extra unit of output, the price falls by enough to cause the firm’s total revenue to decline, even though the firm is selling more units.A Monopoly’s RevenuenullA monopoly maximizes profit by producing the quantity at which marginal revenue equals marginal cost. It then uses the demand curve to find the price that will induce consumers to buy that quantity. 15.2.3 Profit Maximization Figure 4 Profit Maximization for a MonopolyFigure 4 Profit Maximization for a MonopolyCopyright © 2004 South-WesternQuantityQ0Costs andRevenuenullComparing Monopoly and Competition For a competitive firm, price equals marginal cost. P = MR =MC For a monopoly firm, price exceeds marginal cost. P > MR = MC 15.2.3 Profit Maximization nullProfit equals total revenue minus total costs. Profit = TR - TC Profit = (TR/Q - TC/Q) × Q Profit = (P - ATC) ×Q 15.2.4 A Monopoly’s ProfitFigure 5 The Monopolist’s ProfitFigure 5 The Monopolist’s ProfitQuantity0Costs andRevenue15.2.4 A Monopolist’s Profit15.2.4 A Monopolist’s ProfitThe monopolist will receive economic profits as long as price is greater than average total cost.nullnullnullThe monopolist will receive economic profits as long as price is greater than average total cost. What should happen to the price of a drug when the patent runs out ? Figure 6 shows the market for a typical drug. In this figure, the marginal cost of producing the drug is constant. During the life of the patent, the monopoly firm maximizes profit by producing the quantity at which marginal revenue equals marginal cost and charging a price well above marginal cost. But when the patent runs out, the profit from making the drug should encourage new firms to enter the market. As the market becomes more competitive, the price should fall to equal marginal cost.Case study: Monopoly Drugs versus Generic DrugsFigure 6 The Market for DrugsFigure 6 The Market for DrugsCopyright © 2004 South-WesternQuantity0Costs andRevenuenullWhy a Monopoly Does Not have A Supply Curve?You may have noticed that we have analyzed the price in a monopoly market using the market demand curve and the firm’s cost curves. What happened to the supply curve? Although monopoly firms make decisions about what quantity to supply, a monopoly does not have a supply curve. A supply curve tells us the quantity that firms choose to supply at any given price. This concept makes sense when we are analyzing competitive firms, which are price takers, But a monopoly firm is a price maker, not a price taker. It is not meaningful to ask what such a firm would produce at any price because the firm sets the price at the same time it chooses the quantity to supply.nullWhy a Monopoly Does Not have A Supply Curve? Indeed, the monopolist’s decision about how much to supply is impossible to separate from the demand curve it faces. The shape of the demand curve determines the shape of the marginal-revenue curve, which in turn determines the monopolist’s profit-maximizing quantity. In a competitive market, supply decisions can be analyzed without knowing the demand curve, but that is not true in a monopoly market. Therefore, we never talk about a monopoly’s supply curve. (Source: Mankiw, Principles of Economics(2004), third edition, p323.) null垄断厂商的短期均衡 垄断厂商的短期均衡条件为： 　　　　　MR＝SMC 垄断厂商在短期均衡点上可以获得最大利润，可以利润为零，也可以蒙受最小亏损。 (高鸿业,《西方经济学》(微观部分),中国人民大学出版社(2004.9),p218.) null垄断厂商的供给曲线 凡是在或多或少的程度上带有垄断因素的不完全竞争市场中，或者说，凡是在单个厂商对市场价格具有一定的控制力量，相应地，单个厂商的需求曲线向右下方倾斜的市场中，是不存在具有规律性的厂商和行业的短期和长期供给曲线的。 (高鸿业,《西方经济学》(微观部分),中国人民大学出版社(2004.9),p219.) nullnull垄断厂商的长期均衡 垄断厂商在长期内可以调整全部生产要素的投入量即生产规模，从而实现最大利润。 垄断厂商的长期均衡条件为： 　　　　　MR＝LMC＝SMC 垄断厂商在长期均衡点上一般可获得利润。(高鸿业,《西方经济学》(微观部分),中国人民大学出版社(2004.9),p219-221.) null垄断的福利 分析 定性数据统计分析pdf销售业绩分析模板建筑结构震害分析销售进度分析表京东商城竞争战略分析 完全竞争时的产量Q* 是社会有效率的产量(生产者剩余和消费者剩余之和最大的产量，需求曲线和边际成本曲线的交点--图中E点确定的产量). 垄断厂商的产量Q' 要小于完全竞争时的产量Q* (社会有效率的产量)。与完全竞争相比，垄断价格高而产量低；消费者剩余减少(ΔP*EG>ΔP'AG)，生产者剩余增加；总剩余减少，垄断造成了无谓损失(图中ΔABE)null15.3 The Welfare Cost of MonopolyIn contrast to a competitive firm, the monopoly charges a price above the marginal cost. From the standpoint of consumers, this high price makes consumers undesirable. However, from the standpoint of the ownership of the firm, the high price makes monopoly very desirable. Figure 7 The Efficient Level of OutputFigure 7 The Efficient Level of OutputCopyright © 2004 South-WesternQuantity0Price15.3.1 The Deadweight Loss15.3.1 The Deadweight LossBecause a monopoly sets its price above marginal cost, it places a wedge between the consumer’s willingness to pay and the producer’s cost. This wedge causes the quantity sold to fall short of the social optimum.Figure 8 The Inefficiency of MonopolyFigure 8 The Inefficiency of MonopolyCopyright © 2004 South-WesternQuantity0Pricenull15.3.1 The Deadweight LossThe Inefficiency of Monopoly The monopolist produces less than the socially efficient quantity of output. null15.3.1 The Deadweight LossThe deadweight loss caused by a monopoly is similar to the deadweight loss caused by a tax. The difference between the two cases is that the government gets the revenue from a tax, whereas a private firm gets the monopoly profit. null15.4 Public Policy Toward MonopoliesGovernment responds to the problem of monopoly in one of four ways. Making monopolized industries more competitive. Regulating the behavior of monopolies. Turning some private monopolies into public enterprises. Doing nothing at all. null15.4.1 Increasing Competition with Antitrust LawsAntitrust laws are a collection of statutes aimed at curbing monopoly power. Antitrust laws give government various ways to promote competition. They allow government to prevent mergers. such as hypothetical merger between Coca-cola and PepsiCo. They also allow government to break up companies. For example, in 1984 the gov. split up AT&T, the large telecommunications company, into eight smaller companies. Finally, The antitrust laws prevent companies from coordinating their activities in ways that make markets less competitive.nullIncreasing Competition with Antitrust LawsTwo 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 government’s powers and authorized private lawsuits. null15.4.2 Regulation Government may regulate the prices that the monopoly charges. The allocation of resources will be efficient if price is set to equal marginal cost. Figure 9 Marginal-Cost Pricing for a Natural MonopolyFigure 9 Marginal-Cost Pricing for a Natural MonopolyCopyright © 2004 South-WesternQuantity0Pricenull假设某区域新建电网具有垄断性质。（1）在建成初期，如果电网企业追求利润最大化价格(MR=MC，价格为PMC=MR)，电网企业可获得面积ABFPMC=MR的利润。社会福利损失为面积MEF. （2）如果采用边际成本定价( P =MC，价格为PMC)，该电网将承担面积GDEPMC的亏损。 （3）如采用平均成本定价(P =AC，价格为PAC)，电网企业可做到收支平衡。但会有面积为NEC的社会福利损失.null15.4.2 Regulation There are, however, two practical problems with marginal-cost as a regulatory system. The first is illustrated in Figure 9. Natural monopolies, by definition, have declining average total cost. When average total cost is declining, marginal cost is less than average total cost. If regulators are to set price equal to marginal cost, that price will be less than the firm’s average total cost, and the firm will lose money. Instead of charging such a low price, the monopoly firm would just exit the industry. nullRegulation Regulators can respond to this problem in various ways, none of which is perfect. One way is to subsidize the monopolist. In essence, the government picks up the losses inherent in marginal-cost pricing. Yet to pay for the subsidy, the government needs to raise money through taxation, which involves its own deadweight losses. Alternatively, the regulators can allow the monopolist to charge a price higher than marginal cost. If the regulated price equals average total cost, the monopolist earns exactly zero economic profit. Yet average-cost pricing leads to deadweight losses, because the monopolist’s price no longer reflects the marginal cost of producing the good. In essence, average-cost pricing is like a tax on the good the monopolist is selling.nullRegulation The second problem with marginal-cost pricing as a regulatory system is that it gives the monopolist no incentive to reduce costs. Each firm in a competitive market tries to reduce its costs because lower costs mean higher profits. But if a regulated monopolist knows that regulators will reduce prices whenever costs fall, the monopolist will not benefit from lower costs. In practice, regulators deal with this problem by allowing 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.nullThe third policy used by the government to deal with monopoly is public ownership. That is, rather than regulating a natural monopoly that is run by a private firm, the government can run the monopoly itself. This solution is common in many European countries, where the government owns and operates utilities such as the telephone, water, and electric companies. In the United States, the government runs the Postal Service. The delivery of ordinary First Class mail is often thought to be a natural monopoly. 15.4.3 Public Ownership公有制nullEconomists usually prefer private to public ownership of natura