,第10章,市场势力: 垄断与买方垄断,本章要讨论的问题,垄断 垄断势力 垄断形成原因 垄断的社会成本,2,Chapter 1,本章要讨论的问题,买方垄断 买方垄断势力 限制市场势力: 反垄断法,3,Chapter 1,完全竞争,完全竞争回顾 P = LMC = LRAC 长期内只存在正常利润或经济利润为零 大量生产者和消费者 同质化产品 充分信息 企业是价格的接受者,4,Chapter 1,完全竞争,Q,Q,P,P,市场,单个企业,5,Chapter 1,完全垄断,完全垄断 1) 一个生产者 许多消费者 2)一种产品 (没有替代品) 3)市场进入壁垒,6,Chapter 1,完全垄断,完全垄断企业是市场供给方，对其产品的销售能够绝对控制。 当边际收入等于边际成本时，利润达到最大。,7,Chapter 1,完全垄断,确定边际收入 作为唯一的生产者, 垄断企业面对整个市场 假定企业的需求为: P = 6 - Q,8,Chapter 1,总收入、边际收入及平均收入,$60$0- 515$5$5 42834 33913 248-12 155-31,价格 数量 总收入 边际收入 平均收入 PQTRMRAR,9,Chapter 1,Chapter 1,Slide 10,平均收入和边际收入,Q,0,1,2,3,P,1,2,3,4,5,6,7,4,5,6,7,完全垄断,观察 1)只有降价才能增加销售量 2)MR P 3)与完全竞争比较 不需要降价就能增加销售量 MR = P,11,Chapter 1,完全垄断,完全垄断企业的产量决策 当 MR = MC 时利润达到最大化,或,12,Chapter 1,利润最大化,当产量低于 MR = MC 时，收入的减少大于成本的减少 (MR MC). 当产量高于 MR = MC 时，收入的增加小于成本的增加(MR MC),完全垄断企业的产量决策,13,Chapter 1,Chapter 1,Slide 14,Q,P,利润最大化,完全垄断,定价法则 可以将边际收入等于边际成本的原理转化为一个简单实用的法则 其过程可说明如下:,15,Chapter 1,定价法则,16,Chapter 1,定价法则,17,Chapter 1,定价法则,18,Chapter 1,= 边际成本加价在价格中所占比例 【(P-MC)/P】,定价法则,8. 加价等于需求价格弹性的倒数。,19,Chapter 1,定价法则,假设：,20,Chapter 1,完全垄断,完全垄断与完全竞争的价格比较: 完全垄断 P MC 完全竞争 P = MC,21,Chapter 1,完全垄断,完全垄断与完全竞争的价格比较: 需求价格弹性越大，价格越接近于边际成本,22,Chapter 1,完全垄断,需求变化 在完全竞争市场中, 市场供给曲线由边际成本决定； 对于完全垄断企业, 产量由边际成本和需求曲线共同决定；,23,Chapter 1,Chapter 1,Slide 24,需求变动导致价格变动但产量不变,Q,P,Chapter 1,Slide 25,需求变动导致产量变动但价格不变,P,Q,完全垄断,观察 需求变化通常导致价格及需求量都发生变化； 完全垄断市场没有供给曲线；,26,Chapter 1,完全垄断,观察 在相同价格水平下，完全垄断企业可能生产不同数量的产品； 在不同价格水平下，完全垄断企业可能生产相同数量的产品；,27,Chapter 1,Monopoly,The Effect of a Tax Under monopoly price can sometimes rise by more than the amount of the tax. To determine the impact of a tax: t = specific tax MC = MC + t MR = MC + t : optimal production decision,28,Chapter 1,Chapter 1,Slide 29,Effect of Excise Tax on Monopolist,Quantity,$/Q,Question Suppose: Ed = -2 How much would the price change?,Effect of Excise Tax on Monopolist,30,Chapter 1,Answer What would happen to profits?,Effect of Excise Tax on Monopolist,31,Chapter 1,Monopoly,The Multiplant Firm For many firms, production takes place in two or more different plants whose operating cost can differ.,32,Chapter 1,Monopoly,The Multiplant Firm Choosing total output and the output for each plant: The marginal cost in each plant should be equal. The marginal cost should equal the marginal revenue for each plant.,33,Chapter 1,Monopoly,Algebraically:,The Multiplant Firm,34,Chapter 1,Monopoly,Algebraically:,The Multiplant Firm,35,Chapter 1,Monopoly,Algebraically:,The Multiplant Firm,36,Chapter 1,Monopoly,Algebraically:,37,Chapter 1,Chapter 1,Slide 38,Production with Two Plants,Quantity,$/Q,Production with Two Plants,Observations: 1)MCT = MC1 + MC2 2)Profit maximizing output: MCT = MR at QT and P * MR = MR* MR* = MC1 at Q1, MC* = MC2 at Q2 MC1 + MC2 = MCT, Q1 + Q2 = QT, and MR = MC1 + MC2,Quantity,$/Q,D = AR,MR,MC1,MC2,MCT,MR*,Q1,Q2,Q3,P*,39,Chapter 1,Monopoly Power,Monopoly is rare. However, a market with several firms, each facing a downward sloping demand curve will produce so that price exceeds marginal cost.,40,Chapter 1,Monopoly Power,Scenario: Four firms with equal share (5,000) of a market for 20,000 toothbrushes at a price of $1.50.,41,Chapter 1,Quantity,10,000,2.00,QA,$/Q,$/Q,1.50,1.00,20,000,30,000,3,000,5,000,7,000,2.00,1.50,1.00,1.40,1.60,The Demand for Toothbrushes,42,Chapter 1,At a market price of $1.50, elasticity of demand is -1.5.,Quantity,10,000,2.00,QA,$/Q,$/Q,1.50,1.00,20,000,30,000,3,000,5,000,7,000,2.00,1.50,1.00,1.40,1.60,Market Demand,The Demand for Toothbrushes,43,Chapter 1,Monopoly Power,Measuring Monopoly Power In perfect competition: P = MR = MC Monopoly power: P MC,44,Chapter 1,Monopoly Power,Lerners Index of Monopoly Power L = (P - MC)/P The larger the value of L (between 0 and 1) the greater the monopoly power. L is expressed in terms of Ed L = (P - MC)/P = -1/Ed Ed is elasticity of demand for a firm, not the market,45,Chapter 1,Monopoly Power,Monopoly power does not guarantee profits. Profit depends on average cost relative to price. Question: Can you identify any difficulties in using the Lerner Index (L) for public policy?,46,Chapter 1,Monopoly Power,The Rule of Thumb for Pricing Pricing for any firm with monopoly power If Ed is large, markup is small If Ed is small, markup is large,47,Chapter 1,Elasticity of Demand and Price Markup,$/Q,$/Q,Quantity,Quantity,Markup Pricing:Supermarkets to Designer Jeans,Supermarkets,49,Chapter 1,Convenience Stores,Markup Pricing:Supermarkets to Designer Jeans,50,Chapter 1,Convenience stores have more monopoly power. Question: Do convenience stores have higher profits than supermarkets?,Markup Pricing:Supermarkets to Designer Jeans,Convenience Stores,51,Chapter 1,Designer jeans Ed = -3 to -4 Price 33 - 50% MC MC = $12 - $18/pair Wholesale price = $18 - $27,Markup Pricing:Supermarkets to Designer Jeans,Designer Jeans,52,Chapter 1,The Pricing ofPrerecorded Videocassettes,19851999,