国际贸易学课件：Chapter6 Economies of Scale, Imperfect Competition, and International Trade

Slides prepared by Thomas BishopCopyright 2009 Pearson Addison-Wesley.All rights reserved.Chapter 6Economies of Scale,Imperfect Competition,and International Trade6-2Preview Economies of Scale Monopolistic Competition Monopolistic Competition and Trade Inter-industry trade and intra-industry trade Dumping and Anti-Dumping6-3Introduction When defining comparative advantage,the Ricardian and Heckscher-Ohlin models assume that production processes have constant returns to scale(规模报酬不变).But a firm or industry may have increasing returns to scale or economies of scale(规模报酬递增或规模经济):When factors of production change at a certain rate,output increases at a faster rate.A larger scale is more efficient:the cost per unit of output falls as a firm or industry increases output.6-4Introduction(cont.)When economies of scale exist,large firms may be more efficient than small firms,and the industry may consist of a monopoly or a few large firms.一些资源禀赋比较相似、技术实力比较相当的国家（例如欧盟成员国）之间的贸易规模巨大，同一个行业内部的贸易也逐步成为国际贸易的主要组成部分，这些现象不能由传统的贸易理论得到合理解释。规模经济是比较优势的一个重要源泉。Introduction(cont.)经济学的研究要先观察现象，当已有的理论不能解释现象的时候，就是理论创新的开始，克鲁格曼模型就是这样。根据比较优势理论，一国会进口（或出口）其不具有（或其具有）比较优势的产品，但并非同时进口和出口。第二次世界大战后，发达国家间的产业内贸易形势逐渐取代了南北产业间贸易形势，而发达国家间的要素禀赋、技术水平并没有很大的差别，这就很难用我们之前学习的国际贸易模型来解释。克鲁格曼模型的创新之处在于它打破了之前贸易模型中对完全竞争市场结构的假设，使用了垄断竞争的模型。这个模型很好地解释了国家之间的产业内贸易。A Review of Economies of Scale and Monopoly Competition6-66-7Economies of Scale Economies of scale(规模经济)could mean either that larger firms or a larger industry is more efficient:the cost per unit of output falls as a firm or industry increases output.Internal economies of scale(内部规模经济)occur when the cost per unit of output depends on the size of a firm.External economies of scale(外部规模经济)occur when cost per unit of output depends on the size of the industry.Internal Economies of Scale 内部的规模经济内部的规模经济(Internal Economies of scale)：随着工厂或企业规模的扩大，单位产品成本下降。内部规模经济源于内部规模经济源于：工厂规模的扩大，使劳动分工更细，能够发挥劳动力的专业化分工优势，提高劳动生产率。工厂规模扩大，劳动者可以使用更加专业化的设备，并有条件采用新技术或先进的生产线。企业规模的扩大（比如有很多家工厂），可以在多家工厂之间实现专业化分工，发挥专业化生产、专业化管理、专业化设备等优势，提高劳动生产率。多家工厂之间的内部协作、内部资源的共享，可以降低采购和销售费用、管理费用、广告费用等。6-8External Economies of Scale 外部的规模经济外部的规模经济(External Economies of scale)：是指行业规模经济，由于行业内企业数量的增加和产业集聚所引起的产业规模的扩大，使行业中的单个企业获得单位成本下降的好处。例如：北京的中关村，美国的硅谷，义乌的小商品市场，温州的打火机市场，等等。外部规模经济源于：外部规模经济源于：大量企业的集聚加强了市场竞争，促进企业提高技术，改善管理。企业的集聚，使得各企业可以低成本获得行业相关信息，并便捷地获得专业化人才、专业化服务、专业化的零部件供应。企业的集聚带动了基础设施的发展，降低了企业的交通运输及通讯成本。6-96-10Monopoly A monopoly is an industry with only one firm.An oligopoly is an industry with only a few firms.Marginal revenue and product price:In these industries,the marginal revenue generated from selling more products is less than the uniform price charged for each product（垄断厂商的边际收益低于消费者愿意支付的价格，即边际收益曲线位于需求曲线的下方）.A monopolistic firm chooses an output at which marginal revenue equals marginal cost.In the monopolistic model of trade,the economies of scale occur at the level of the individual firm(在垄断市场中，规模经济通常存在一个企业内部).6-11Fig.6-1:Monopolistic Pricing and Production Decisions由于规模经济的存在，垄断企业的平均生产成本随产量扩张而下降。6-12Monopoly(cont.)Suppose that costs are represented by C=F+cQ,where F represents fixed costs,c represents a constant marginal cost.Average cost is the cost of production(C)divided by the total quantity of production(Q),AC=F/Q+c.A larger firm is more efficient because average cost decreases as output Q increases:internal economies of scale.Marginal cost is the cost of producing an additional unit of output.Average cost approaches infinity at zero output,and approaches marginal cost at very large output.6-13Fig.6-2:Average Versus Marginal Cost6-14Monopolistic CompetitionMonopolistic competition(垄断竞争垄断竞争)is a model of an imperfectly competitive industry which assumes that:1.Each firm can differentiate its product from the product of competitors and set the price of its product.2.Each firm ignores the impact that changes in its price will have on the prices that competitors set:even though each firm faces competition it behaves as if it were a monopolist.3.The economies of scale occur at the level of the individual firm.6-15Monopolistic Competition(cont.)The number of firms and average cost(CC curve)The more firms there are,the lower the output of each firm,and thus the higher its cost per unit output.The number of firms and the price(PP curve)The more firms there are,the more intense is competition among firms,and as a result the lower the prices they charge.The equilibrium number of firms In the long run,when the price is exceeds average cost additional firms will enter the industry,while when the price is less than average cost firms will exit.6-16Fig.6-3:Equilibrium in a Monopolistically Competitive MarketEconomies of Scale,Monopolistic Competition and Trade6-176-18Economies of Scale and Trade The Effects of Increased Market SizeBecause trade increases market size(贸易扩大了市场规模),trade is predicted to decrease average cost in an industry described by monopolistic competition.Because trade increases the variety of goods that consumers can buy under monopolistic competition,and because average costs decrease,consumers can also benefit from a decreased price,it increases the welfare of consumers.As a result of trade,the number of firms in a new international industry is predicted to increase relative to each national market.6-19Fig.6-4:Effects of a Larger Market市场规模扩大后，即使厂商的数目不变，但由于更大的市场，各厂商的销售量增加，因此平均成本下降，CC曲线向右下方平移。结果是，厂商数目增加，商品的价格下降。Market Size and Trade 贸易能够扩大市场规模的思想是垄断竞争模型（存在规模经济）在贸易中运用的基础。在具有规模经济的行业中，一国生产的产品种类及其生产规模都受到该国市场规模的限制。国际贸易可以创造一个更大的市场，在这个大市场中，各厂商可以以更大的规模专业化生产少数类型的商品，降低平均成本；消费者能以更低的价格获取种类更加丰富的商品。为了实现一体化带来的好处，各国必须参与国际贸易。为了实现规模经济，各国必须集中生产少数几种类型的产品，但必须在更大的国际市场上销售。因此，任何产品主要在某一国生产并出口到其他国家。6-20Monopoly Competition and Trade 产品的差异化与国际贸易 从各行业的商品结构来看，初级产品之间的贸易通常是产业间贸易(Inter-industry Trade)，而存在大量差异的制造品之间的贸易主要是产业内贸易(Intra-industry Trade)。在现代经济中，大部分产品是有差别的，而不是同质的。例如，一辆雪佛莱汽车与丰田、大众、沃尔沃或奔驰汽车都是不完全相同的，这就使得国际贸易中有很大一部分包含了同一产业内或同一类商品组中差别产品的交易。规模经济与国际贸易 从各国制造品生产者的规模及其对市场的影响力来看，现在生产和出口商品的大多都不是小企业，企业的数目也不多，而是在国际贸易中占重要地位的少数几家大企业，例如汽车行业。6-216-22Inter-industry Trade(产业间贸易)According to the Heckscher-Ohlin model or Ricardian model,countries specialize in production.Trade occurs only between industries:inter-industry trade In a Heckscher-Ohlin model suppose that:The capital abundant domestic economy specializes in the production of capital intensive cloth,which is imported by the foreign economy.The labor abundant foreign economy specializes in the production of labor intensive food,which is imported by the domestic economy.6-23Fig.6-6:Trade in a World Without Increasing Returns当不存在规模经济，且各国产品无差异时，一国专业化生产并且出口密集使用本国丰裕要素的产品，进口密集使用本国稀缺要素的产品，因此只有棉布和粮食之间的贸易（本国出口棉布，外国出口粮食），不存在产业内贸易。6-24Intra-industry Trade(产业内贸易)Suppose now that the global cloth industry is described by the monopolistic competition model.Because of product differentiation,suppose that each country produces different types of cloth.Because of economies of scale,a country can produce cloth at a larger scale with higher productivity and lower costs,the foreign and domestic country both export some cloth.Trade occurs within the cloth industry:intra-industry trade6-25Fig.6-7:Trade with Increasing Returns and Monopolistic Competition如果棉布制造业是个垄断竞争行业，那么本国和外国将生产具有差别的棉布。因此，即使本国是棉布的净出口国，外国也会在某些棉布生产中具有规模经济，而且外国生产的不同的棉布可以满足部分本国消费需求，从而对本国出口部分棉布。因此，本国在其出口棉布的同时，也会进口一些棉布，从而形成产业内贸易。Index of Intra-Industrial Trade产业内贸易指数（Index of intra-industrial trade,IIT）表示产业内贸易在国际贸易中所占比重，用来衡量产业内贸易的发展程度。式中，Ti为i产品D的产业内贸易指数；Xi和Mi分别表示一国i商品的出口额和进口额。Ti（0，1），当一个国家只有出口或只有进口产品i时（即不存在产业内贸易），Ti=0。当某一商品i的进口等于出口时，Ti=1（产业内贸易达到最大）。6-261iiiiiXMIITXM 6-27Inter-industry and Intra-industry Trade1.Gains from inter-industry trade reflect comparative advantage.2.Gains from intra-industry trade reflect lower costs(economies of scale)and wider consumer choices(differentiated good).3.The relative importance of intra-industry trade depends on how similar countries are.Countries with similar relative amounts of factors of production are predicted to have intra-industry trade.Countries with different relative amounts of factors of production are predicted to have inter-industry trade.Gains from Intra-industry Trade Intra-industry trade produces extra gains from international trade,because intra-industry trade allows countries to benefit from large market.By engaging in intra-industry trade,a country can produce fewer varieties at larger scale,with higher productivity and lower costs.At the same time,consumers benefit from the increased range of choice.Scale economies and product differentiation are important,so that the gains from larger scale and increased choice are large.6-28产业内贸易实例：产业内贸易实例：1964年年北美汽车贸易协定北美汽车贸易协定20世纪60年代后半期，美国和加拿大之间汽车贸易协定的发展是一个特别明显的产业内贸易的例子，它清晰地展现了规模经济在促进国际贸易中的作用。1965年以前，加拿大和美国的关税保护使得加拿大成为一个汽车基本自给自足的国家，进口不多，出口也少得可怜。且加拿大的汽车工业被美国汽车工业的几个大厂商所控制。为绕过关税壁垒，美国厂商在加拿大建立了分散的生产体系（进行直接投资）。但是美国厂商在加拿大的子公司发现了小规模带来的种种不利。一部分原因是，在加拿大的分厂比其在美国的分厂要小，但重要的原因是美国的工厂更加专一（集中精力生产单一车型的汽车或配件）。而加拿大的工厂不得不生产各种各样的产品，以至于工厂不得不经常停产以实现从一个产品项目到另一个产品项目的转换；不得不保持较多的库存；不得不少采用专业化的机器设备，等等。结果，加拿大汽车工业的劳动生产率比美国低30%。6-29 为了解决这些问题，美国和加拿大政府通过努力于1964年建立了一个汽车自由贸易区。这一举措使得汽车厂商得以重组：美国厂商在加拿大各子公司大力削减产品种类。例如，通用汽车削减了其在加拿大生产的汽车车型的一半。加拿大一方面从美国进口自己不在生产的汽车车型，另一方面向美国出口加拿大仍在生产的车型。1962年，加拿大向美国出口了价值1600万美元的汽车产品，从美国进口了价值5.19亿美元的汽车产品。但是到了1968年，这两个数字已分你别为24亿美元和29亿美元。换言之，加拿大的汽车进口和出口均大幅度增长。6-30Dumping and Anti-Dumping(倾销和反倾销)6-316-32Dumping:An Example of Monopoly Competition and Trade)Dumping is the practice of charging a lower price for exported goods than for goods sold domestically.Dumping is an example of price discrimination(价格歧视):the practice of charging different customers different prices.Price discrimination and dumping may occur only if imperfect competition exists:firms are able to influence market prices.markets are segmented so that goods are not easily bought in one market and resold in another.6-33Dumping(cont.)Dumping may be a profit maximizing strategy because of differences in foreign and domestic markets.One difference is that domestic firms usually have a larger share of the domestic market than they do of foreign markets.Because of less market dominance and more competition in foreign markets,foreign sales are usually more responsive to price changes than domestic sales.由于厂商在国内的市场份额大于其在国际市场中的份额（即在国内市场类似一个垄断者，在国际市场中类似一个竞争者），国外消费者对价格的敏感程度更高（厂商面临的国外消费者需求曲线更平坦，消费者需求弹性更大），所以对国外消费者制定的价格更低。6-34Dumping(cont.)We draw a diagram of how dumping occurs when a firm is a monopolist in the domestic market but must compete in foreign markets.Because the firm is a monopolist in the domestic market,the demand function that it faces in the domestic market is downward sloping,and marginal revenue from additional output is always less than a uniform price for all units of output.Because the firm competes in foreign markets,the demand function that it faces in foreign markets is more horizontal,representing the fact that exports are very responsive to small price changes.,P MRdPdEdMRdD,P MRfPfEfMRfDdQfQoooEQEMRMCEMC,MC MRQQQ(a)本国市场本国市场(b)国外市场国外市场(c)两个市场总和两个市场总和倾销与企业的利润最大化E点是垄断企业获得最大利润的生产均衡点。根据利润最大化要求，企业在各个市场上都应是MR=MC，沿着MCE水平线在(a)和(b)中找到国内外市场的生产均衡点Ed和Ef。使企业利润最大化的总产量中，国内销售量为Qd，国外销售量为Qf。在价格方面，国内和国外市场价格分别是Pd和Pf，且PdPf。6-36Anti-Dumping Dumping(as well as price discrimination in domestic markets)is widely regarded as unfair.(倾销被认为是一种不公平的贸易行为)A US firm may appeal to the Commerce Department to investigate if dumping by foreign firms has injured the US firm.The Commerce Department may impose an“anti-dumping duty(反倾销税),”or tax,as a precaution against possible injury.