modelofinternatioanltradeTheoryandPolicy西安交通大学,冯宗宪
什么是国际经济学
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国际经济学的发展概况
• 国际贸易理论的发展 • 国际金融理论的发展
国际贸易理论的发展 (1)
• • • 1．重商主义者以其错误的财富观为基础，推论出“奖出限入”的贸易政策。 2．1776年，亚当· 斯密（Adam Smith）在《国富论》（The Welth of Nations）中，系统阐述了分工 和自由经济的观点，批判了重商主义的财富观和贸易观，提出了国际贸易的绝对优势理论（Theory of Absolute Advantage）。 3．1817年，大卫· 李嘉图（David Ricardo）在《政治经济学及赋税原理》（The Principles of Political Economy and Taxation）一书中，进一步发展了亚当· 斯密的理论，正确地提出和论证了国 际贸易的比较优势原理（Law of Comparative Advantage），确立了其后贸易理论发展的方向。后 来的学者都将国际贸易研究的重点放在比较优势原理上，不断探索决定比较优势的各种因素。 4．穆勒（l）、马歇尔（Alfred Marshall）和艾奇沃思（F.Y.Edgeworth）等，集中研究了 贸易条件的决定问题。 5．1919年，赫克歇尔（E.F.Heckscher）在《对外贸易对收入分配的影响》（The Effect of Foreign Trade on the Distribution of Income）一文中，首先论述了各国要素禀赋构成与贸易形态之间的关系， 以及贸易对各国收入分配的影响，提出了要素禀赋差异是决定国际分工和贸易的基础的观点。其后， 他的学生俄林（Bertil Ohlin）在1933年出版的《区际贸易与国际贸易》（Interregional and International Trade）一书中，进一步阐述和发挥了赫克歇尔的要素禀赋理论。因而后来人们又称要 素禀赋理论为赫克歇尔——俄林理论（Heckscher-Ohlin Theory，简称H—O理论）。 6．1936年，哈伯勒（G.Haberler）在《国际贸易理论》（Theory of International Trade）一书中， 用机会成本理论（Opportunity Cost Theory）解释了比较优势原理，在贸易理论的模型化方面作出 了实质性的贡献。此外，勒纳（A.P.Lerner）、里昂惕夫（W.Leontief）、米德（J.E.Meade）、 萨缪尔逊（P.A.Samuelson）等人将一般均衡分析的新古典模型与赫克歇尔和俄林的要素禀赋理论 融为一体，最终形成了国际贸易理论的标准模型。可以说，这一标准化的贸易模型，就是新古典学派 一般均衡理论在国际贸易研究中的具体应用。 7．1951年，里昂惕夫首次运用投入产出方法对H—O理论进行了经验检验，发现美国作为世界上资 本最丰富的国家，其出口部门是劳动密集型的，而进口替代部门则是资本密集型的，这就与H—O理 论预测的贸易模式相反，这就是著名的“里昂惕夫之谜”（The Leontief Paradox）。 8．20世纪70年代末80年代初，以克鲁格曼（P.R.Krugman）和赫尔普曼（E.Helpman）为代表的 一批经济学家，提出了所谓“新贸易理论”（New Trade Theory）。新贸易理论认为，除要素禀赋 差异外，规模经济亦是国际贸易的原因和贸易利益的另一个独立决定因素。
国际贸易经典文献模型推导（四）
国际贸易经典文献模型推导（四）导读
克鲁格曼论文中的主要模型和推导脉络
Increasing returns，monopolistic competition and international trade
By Paul R.KRUGMAN (1979)
报酬递增、垄断竞争与国际贸易
克鲁格曼（1979）
摘要
建立一个关于比较优势贸易的简单的、一般均衡模型。
贸易起源于内生于企业的规模经济。
由于存在规模经济，市场不完全竞争，甚至两个具有相同偏好、技术和要素禀赋的国家都能进行贸易，并且从中获利。
动机
现有很过实证研究发现：
1、很多世界贸易发生在具有相同要素禀赋的国家
2、世界贸易中很大一部分是产业内贸易
3、二战后，贸易的扩张并没有伴随大规模的资源重新分配和收入分配效应
想法
主要包含两个方面：
1、规模经济使一国仅生产产业内的不同种类的产品，从而也存在产业内的分工与贸易。
由于规模经济的存在，具有相同要素禀赋的国家间仍可以进行贸易，这些国家的贸易以产业内贸易为主；
2、如果两个国家足够相似，从较大市场中获益将超过产业间贸易产生收入分配效应
封闭经济下的垄断竞争
增长、贸易和要素移动
注明：感谢浙江工商大学刘文革老师把他多年高级国际贸易学讲义奉献出来，供大家参考与分享。
如有不足之处，请与平台联系。
高级国际贸易学第一章李嘉图模型
产品价格变化分析 假定产品1的价格相对上升，即
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将该结果与两个国家、一个部门时的结果相比：只 有一个部门时，通过贸易实现的产品价格的均等不 一定实现要素价格的均等：劳动力丰裕的国家有较 低的工资水平。为什么该结论在两部门时就不存在 了呢？答案是劳动力丰裕的国家可以生产并出口更 多的劳动密集型产品。
斯托尔帕——萨缪尔森定理
一种产品相对价格上升，将导致该产品 密集使用的生产要素实际报酬或实际价 格提高，另一种生产要素实际报酬或实 际价格下降。
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相对需求曲线与相对供给曲线
当p ＜ pa且p＜pa*时，两个国家都专业生产商 品2，因为商品2的价格高，所以世界商品1的 总供给为0； 当pa＜p ＜pa*时，本国全部资源 用来生产商品1（数量为L/ a1 ），外国全部资 源 此用时来的相生对产供商给品（2，y1（+数y*1量）为/(Ly*2/+ay**22)为）一，常所数以， 与p大小无关，在图形上为一条垂直线；当p ＞pa且p ＞ pa*时，两个国家专业生产商品1， 其供求关系如图：
PARTⅠTrade theory (ch.1-7)国际经济学 克鲁格曼
Brief ContentPreface 11 Introduction2 PartⅠInternational Trade Theory 42 World Trade: An Overview 43 Labor Productivity and Comparative Advantage:The Ricardian Model 84 Resources, Comparative Advantage, and Income Distribution 145 The Standard Trade Model 256 Economies of Scale, Imperfect Competition and International Trade 317 International Factor Movements 40 PartⅡInternational Trade Policy 468 The Instruments of Trade Policy 469 The Political Economy of Trade Policy 5210 Trade Policy in Developing Countries 5811 Controversies in Trade Policy 62Preface§1. Some distinctive features of International Economics: Theory and Policy.This book emphasizes several of the newer topics that previous authors failed to treat in a systematic way:·Asset market approach to exchange rate determination.·Increasing returns and market structure.·Politics and theory of trade policy.·International macroeconomic policy coordination·The word capital market and developing countries.·International factor movements.§2. Learning features:·Case studies·Special boxes·Captioned diagrams·Summary and key terms·Problems·Further reading§3.Reference books:·[美]保罗•克鲁格曼，茅瑞斯•奥伯斯法尔德，《国际经济学》，第8版，中译本，中国人民大学出版社，2012.·Dominick Salvatore, International Economics, Prentice Hall International, 2011.Chapter 1Introduction·Nations are more closely linked through trade in goods and services, through flows of money, and through investment than ever before.§1. What is international economics about?Seven themes recur throughout the study of international economics: ·The gains from trade(National welfare and income distribution)·The pattern of trade·Protectionism·The balance of payments·Exchange rate determination·International macroeconomic policy coordination·International capital market§2. International economics: trade and money·Part I (chapters 2 through 7) :international trade theory·Part II (chapters 8 through 11) : international trade policy·Part III (chapters 12 through 17) : international monetary theory ·Part IV (chapters 18 through 22) : international monetary policyChapter 2World Trade: An Overview§1 Who Trades with Whom?1. Size Matters: The Gravity Model•The size of an economy is directly related to the volume of imports and exports.•Larger economies produce more goods and services, so they have more to sell in the export market. Larger economies generate more income from the goods and services sold, so people are able to buy more imports.• 3 of the top 10 trading partners with the US in 2003 were also the 3 largest European economies: Germany, UK and France. These countries have the largest gross domestic product (GDP) in Europe.Cultural affinity: if two countries have cultural ties, it is likely that they also have strong economic ties.Geography: ocean harbors and a lack of mountain barriers make transportation and tradeeasier.2. Distance Matters: The Gravity ModelDistance between markets influences transportation costs and therefore the cost of imports and exports. Distance may also influence personal contact and communication, which may influence trade.Estimates of the effect of distance from the gravity model predict that a 1% increase in the distance between countries is associated with a decrease in the volume of trade of 0.7% to 1%.Borders: crossing borders involves formalities that take time and perhaps monetary costs like tariffs. These implicit and explicit costs reduce trade. The existence of borders may also indicate the existence of different languages or different currencies, either of which may impede trade more.3.The gravity modelThe gravity model is:a b c ij i j ijT A Y Y D =⨯⨯ where a, b, and c are allowed to differ from 1.（Table 2-1 Example ）§2. The Changing Composition of Trade1. Has the World Become “Smaller ”?There were two waves of globalization.1840–1914: economies relied on steam power, railroads, telegraph, telephones. Globalization was interrupted and reversed by wars and depression.1945–present: economies rely on telephones, airplanes, computers, internet, fiber optics,…2. Changing Composition of TradeToday, most of the volume of trade is in manufactured products such as automobiles, computers, clothing and machinery.Services such as shipping, insurance, legal fees and spending by tourists account for 20% of the volume of trade.Mineral products (e.g., petroleum, coal, copper) and agricultural products are a relatively small part of trade.Multinational Corporations and OutsourcingBefore 1945, multinational corporations played a small role world trade.But today about one third of all US exports and 42% of all US imports are sales from onedivision of a multinational corporation to another.Chapter 3Labor Productivity and Comparative Advantage:The Ricardian Model*Countries engage in international trade for two basic reasons:·Comparative advantage: countries are different in technology (chapter 3) or resource (chapter 4).·Economics of scale (chapter 6).*All motives are at work in the real world but only one motive is present in each trade model.§1. The concept of comparative advantage1. Opportunity cost : The opportunity cost of roses in terms of computers is the number of computers that could have been produced with the resources used to produce a given number of roses.Table 3-1 Hypothetical Changes in ProductionMillion Roses Thousand Computers United States－10 ＋100 South America＋10 －30 Total 0 ＋702. Comparative advantage : A country has a comparative advantage in producing a good if the opportunity cost of producing that good in terms of other goods is lower in that country than it is in other countries.·Denoted by opportunity cost.·A relative concept : relative labor productivity or relative abundance.3. The pattern of trade: Trade between two countries can benefit both countries if each country exports the goods in which it has a comparative advantage.§2. A one-factor economy1.production possibilities: LC C LW W a Q a Q L +≤Figure 3-1 Home’s Production Possibility Frontier2. Relative price and supply·Labor will move to the sector which pays higher wage.·If C W LC LW P P a a >(C LC W LW P a P a >, wage in the cheese sector is higher ), the economy willspecialize in the production of cheese.·In a closed economy, C W LC LW P P a a =.·If each country has absolute advantage in one good respectively, will there exist comparative advantage?§3. Trade in a one-factor world·Model : 2×1×2·Assume: **LC LW LC LW a a a a <Home has a comparative advantage in cheese.Home ’s relative productivity in cheese is higher.Home ’s pretrade relative price of cheese is lower than foreign.·The condition under which home has the comparative advantage involves all four unit labor requirement, not just two.1. Determining the relative price after trade·Relative price is more important than absolute price, when people make decisions on production and consumption.·General equilibrium analysis: RS equals RD . (World general equilibrium)·RS : a “step ” with flat sections linked by a vertical section. **(/)/)LC LW L a L aFigure 3-3 World Relative Supply and Demand·RD : subsititution effects·Relative price after trade: between the two countries ’ pretrade price.(How will the size of the trading countries affect the relative price after trade? Which country ’s living condition improves more? Is it possible that a country produce both goods?)2. The gains from tradeThe mutual gain can be demonstrated in two alternative ways.·To think of trade as an indirect method of production :(1/)()1/LC C W LW a P P a > or C W LC LW P P a a >·To examine how trade affects each country ’s possibilities of consumption.Figure 3-4 Trade Expands Consumption Possibilities(How will the terms of trade change in the long-term? Are there income distribution effects within countries? )3. A numerical example:·Two crucial points :When two countries specialize in producing the goods in which they have a comparative advantage, both countries gain from trade.Comparative advantage must not be confused with absolute advantage; it is comparative, not absolute, advantage that determines who will and should produce a good.Table 3-2 Unit Labor RequirementsCheese WineHome 1LC a = hour per pound 2LW a = hours per gallonForeign *6LC a = hours per pound *3LW a = hours per gallonabsolute advantage; relative price; specialization; the gains from trade.4. Relative wages·It is precisely because the relative wage is between the relative productivities that each country ends up with a cost advantage in one good.***LC LC LW LW a a w w a >> **LC LC wa w a <；**LW LW wa w a >·Relative wages depend on relative productivity and relative demand on goods.Special box: Do wages reflect productivity?·Debates about relative wages and relative labor productivity.·Long-run convergence in productivity produces long-run convergence in wages.§4. Misconceptions about comparative advantageThe proposition that trade is beneficial is unqualified. That is, there is no requirement that a country be “competitive ” or that the trade be “fair ”.1. Productivity and competitivenessmyth1: Free trade is beneficial only if your country is strong enough to stand up to foreigncompetition.·The gains from trade depend on comparative advantage rather than absolute advantage.·The competitive advantage of an industry depend on relative labor productivity and relative wage. ·Absolute advantage: neither a necessary nor a sufficient condition for comparative advantage (or for the gains from trade).2. The pauper labor argumentmyth2: Foreign competition is unfair and hurts other countries when it is based on low wages. ·Whether the lower cost of foreign export goods is due to high productivity or low wages does not matter. All that matter to home is that it is more efficient to “produce ” those goods indirectly than to produce directly.3. Exploitationmyth3: Trade exploits a country and makes it worse off if its workers receive much lower wagethan workers in other nations.·Whether they and their country are worse off?·What is the alternative ?(If it refuses to trade, real wages would be even lower).§5. Comparative advantage with many goods·Model: 2×1×n·For any good we can calculate *Li Li a a , label the goods so that the lower the number, the lower this ratio. ***1122L L L L LN LN a a a a a a <<<(or ***1122L L L L L N L N a a a a a a>>> ) 1. Relative wages and specialization·Any good for which **Li Li a a w w >will be produced in home. Relative productivity is higher thanits relative wage,**Li Li wa w a <, goods will always be produced where it is cheapest to make them.·All the goods to the left of the cut end up being produced in home.Table 3-3 Home and Foreign Unit Labor RequirementsApples1 10 10 Bananas5 40 8 Caviar3 124 Dates6 12 2 Enchiladas12 9 0.75 ·if *3w w =, A 、B 、C will be produced in Home and D 、E in foreign.(Hint: Comparing the labor cost of producing a (import) good directly and indirectly).2. Determining the relative wage in the multigood model·*w w: RD of labor equals RS of labor.·The relative derived demand for home labor (*L L) will fall when the ratio of home to foreign wages (*w w) rises, because:(1)The goods produced in home became relative more expensive.(2)Fewer foods will be produced in home and more in foreign.Figure 3-5Determination of relative of wages.RD: derived form relative demand for home and foreign goods.RS: determined by relative size of home and foreign labor force (Labor can’t move between countries).§6. Adding transport costs and nontraded goods·There are three main reasons why specialization in the real international economy is not so extreme:(1) the existence of more than one factor of production(2) protectionism(3) the existence of transport cost.E.g. suppose transport cost is a uniform fraction of production cost, say 100 percents. For goods Cand D in table 2-4:D: Home 6hours < 12hours×1/3×2 foreignC: Home 3hours×2 >12hours×1/3 foreignThus, C and D became nontraded goods.·In practice there is a wide range of transportation costs.In some cases transportation is virtually impossible: services such as haircut and auto repair ;goods with high weight-to-value ratio, like cement.·Nontraded goods: because of absence of strong national cost advantage or because of high transportation cost.·Nations spend a large share of their income on nontraded goods.§7. Empirical evidence on the Ricardian model·Misleading predictions :(1)An extreme degree of specialization;(2)Neglect the effects on income distribution;(3)Neglect differences in resources among countries as a cause of trade;(4)Neglect economics of scale as a cause of trade.·The basic prediction of the Ricardian model has been strongly confirmed by a number of studies over years.(1) Countries tend to export those goods in which their productivity is relative high.(2) Trade depends on comparative not absolute advantage.Figure 3-6productivity and exportsChapter 4Resources, Comparative Advantage, and Income Distribution(Factor endowment theory)*Comparative advantage is influence by the interaction between relative abundance and relative intensity.*Relative abundance: the proportions of different factors of production are available in different countries.If(T/L)H<(T/L)F, Home is labor-abundant and Foreign is land-abundant“per captia”,“relative” , no country is abundant in everything.*Relative intensity: the proportions of different factors of production are used in producing different goods.At any given factor prices, if (T C/L C) < (T F/L F), production of Cloth is labor-intensive and production of Food is land-intensive. A good can’t be both labor-intensive and land-intensive.(Factor-proportions theory)§1. A model of two-factor economy1. Assumption of the modelThe same two factors are used in both sectors: T、L ; Cloth、Food.(1)Alternative input combinations: In each sector, the ratio of land to labor used in production depends on the cost of labor relative to the cost of land, w/r.Figure 4A-2/L C↑and T F/L F↑)w/r↑L↑(T(2) Relative intensityAt any given wage-rental ratio, food production use a higher land-labor ratio, food production is land-intensive and cloth production is labor-intensive.2. Factor price and goods prices(1)One-to-one relationshipBecause cloth production is labor-intensive while food production is land-intensive. The one dollar worth isoquant line of cloth and food are shown as Figure4A-3).The two isoquants CC and FF are tangent to the same unit isocost line.Figure 4 A-3When P C raises, the slope of the unit isocost line w/r rises, that is, there is one-to-one relationship between factor price ratio w/r and the relative price of cloth P C/P F (Figure4A-4). The relationship is illustrated by the curve SS.(Suppose the economy produce both cloth and food).Figure 4 A-4If the relative price of a good rises, the real income of the factor which intensively used in that goodW/P C=MPL C↑, W/P F=MPL F↑Figure 4-73. Resources and output(1)Relative price、resources and productionGiven the prices of cloth and food and the supply of land and labor, it is possible to determine howmuch of each resource the economy devoted to the production of each good; and thus also todetermine the econom y’s output of each good.the slope of OcC is Tc/Lc , the slope of O F F is T F /L F• In general, the economy aims to maximizes the value of production:C C F F V P Q P Q =+ or F F C F C Q V P P P Q =-(2)Rybczynski effectIf goods prices remain unchanged, an increase in the supply of land will rise the output of food more than proportion to this increase, while the output of cloth will fall.T T↑L F↑;T C↓L C Q F↑Q C↓Rybczynski effect: At unchanged relative goods price, if the supply of a factor of production increases, the output of the good that are intensive in that factor will rise, while the output of the other good will fall.Figure 4-10·The economy could produce more of both cloth and food than before.·A biased expansion of production possibilities.·An economy will tend to be relatively effective at producing goods that are intensive in thatfactors with which the country is relative well-endowed.§2. Effects of international trade between two-factor economies1. Resources 、relative prices and the pattern of tradeAs always, Home and Foreign are similar along many dimensions, such as relative demand and technology. The only difference between the countries is their resources: Home has a lower ratio of land to labor than Foreign does.·relative abundance relative supply relative prices tradeFigure 4-11·H-O proposition: Countries tend to export goods whose production is intensive in factors with which they are abundantly endowed.·Budget constraint: C C F F C C F P D P D P Q P Q+=+ or ()()F F C F C C D Q P P Q D -=⨯-2. Trade and the distribution of income·According to Stolper-Samuelson effect, a rise in the price of cloth raises the purchasing power of labor in terms of both goods, while a rise in the price of food declines the purchasing power of land in terms of both goods.·Owners of a country’s abundant factors gain from trade, but owners of a country’s scare factors lose.3. Factor price equalization·Factor price equalization proposition: International trade produces a convergence of relative goods prices. This convergence, in turns, causes the convergence of the relative factor prices. Trade leads to complete equalization of factor prices. (Figure4-11,4-7 or Figure 4A-3)Figure 4A-3one-dollar-worth isoquant lines.goods’ price and technologies are the same, so CC、FF are the same in both countries.w/r are the same in both countries.·In an indirect way the two countries are in effect trading factors of production.（Home exports labor: more labor is embodied in Home’s exports than its imports ；Foreign exports land: more land is embodied in Foreign exports than its imports.）·In the real world factor prices are not equalized (Table4-1). Why?Table 4-1 Comparative international Wage Rates (United States=I00)Hourly compensationCountry of production workers, 2000United States 100 Germany121 Japan111 Spain55 South Korea41 Portugal24 Mexico12 Sri Lanka* 2*1969Source: Bureau of Labor Statistics, Foreign Labor Statistics Home Page. Three assumptions crucial to the prediction of factor price equalization are in reality certainly untrue.(1)Both countries produce both goods.(Trading countries are sufficiently similar in their relative factor endowments)(2)Technologies are the sameTrade actually equalizes the prices of goods in two countries.(3)There are barriers to trade: natural barriers (such as transportation costs) and artificial barriers (such as tariffs, import quotas, and other restrictions).Case study: North-south trade and income inequality·Why has wage inequality in U.S. increased between the late 1970s and the early 2000s?(1)Many observers attribute the change to the growth of world trade and in particular to the growing exports of manufactured goods from NIEs .(2)Most empirical workers believed that trade has been at most a contributing factor to thegrowing inequality and that the main villain is technology.§3. The political economy of trade: a preliminary view1. Income distribution in the short run·specific factor(,)M M M Q Q K L =；(,)F F F Q Q T L =·Trade benefits the factor that is specific to the export sector of each country but hurts the factor to the import-competing sectors, with ambiguous effects on mobile factors.·Does trade make each country better off? Is trade potentially a source of gain to everyone?The fundamental reason why trade potentially benefits a country is that it expands the economy ’s choices. This expansion of choice means that it is always possible to redistribute income in such a way that everyone gains from trade.It is possible in principle for a country ’s government to use taxes and subsidies to redistribute income to give each individual more of both goods.·The distinction between income distribution effects due to immobility and those due to differences in factor intensity.The specific factor model: Sectors; temporaryThe H-O model: Factors; permanent·Resources and trade (factor endowment theory)Short-run analysis: the specific factor modelLong-run analysis: H-O model2. Optimal trade policy.There are two ways to look at trade policy:(1) (Normative analysis) given its objectives, what should the government do? What is theoptimal trade policy?(2) (Positive analysis) what are the governments likely to do in practice?·Economists: to maximize the national welfare, free international trade is the optimal policy. ·Three main reasons why economists do not regard the income distribution effects of trade as a good reason to limit trade (P70).3. Income distribution and trade politics.·An example : an import quota : U.S. sugar (P191).·Problems of collective action (P 219).·Typically, those who lose from trade in any particular product are a much more concentrated, informed, and organized group than those who gain.·The formulation of trade policy: A kind of political process.§4. Empirical evidence on the H-O model1.Tests on U.S data. (Table4-2)Table 4-2 Factor Content of U.S. Exports and Imports for 1962Imports Exports Capital per million dollars $2,132,000 $1,876,000Labor(person-years) per million dollars 119 131Capital-labor ratio (dollars per worker) $17,916 $14,321Average years of education per worker 9.9 10.1Source: Rodert Baldwin, “Determinants of the Commodity Structure of U.S. Trade,”American Economic Review 61 (March1971), pp.126-145·Leontief paradox: U.S. exports were less capital-intensive than U.S. imports. (Capital-labor ratio) ·U.S. exports were more skilled labor-intensive and technology-intensive than its imports. (Average years of education; scientists and engineering per unit of sales)·A plausible explanation: U.S. may be exporting goods that heavily use skilled labor and innovative entrepreneurship(such as aircraft and computer chips), while importing heavy manufactures that use large amounts of capital (such as automobiles).2.Tests on global data. (Table 4-3)Table 4-3 Testing the Heckscher-Ohlin ModelFactor of Production Predictive Success*Capital 0.52Labor 0.67Professional workers 0.78Managerial workers 0.22Clerical workers 0.59Sales workers 0.67Service workers 0.67Agricultural workers 0.63Production workers 0.70Arable land 0.70Pasture land 0.52Forest 0.70*Fraction of countries for which net exports of factor runs in predicted direction.Source: Harry P.Bowen, Edward E. Leamer, and Leo Sveikauskas,“Multicountry,Multifactor Tests of the Factor Abundance Theory,”American EconomicReview 77 (December 1987), pp.791-809.·If the factor-proportion theory was right, a country would always export factors for which the factor share exceeded the income share, import factors for which it was less.·Two-thirds of the factors were trading in the predicted direction less than 70 percents of the time. This result confirms the Leontief paradox on a broader level: Trade ofte n doesn’t run in the direction that the H-O theory predicts.3. Test on North-South tradeNorth-South trade in manufactures seems to fit the H-O theory much better.4. The case of the missing trade.·A previously overlooked empirical problems: The H-O model can predict not only the direction but the volume of trade.·Factor trade in general turns out to be much smaller than the H-O model predicts.·A large part of the reason for this disparity comes from a false prediction of large-scale trade in labor between rich and poor countries.·This puzzle can be resolved only by dropping the H-O assumptions that technologies are the same across countries. (Table4-5)Table 4-5 Estimated Technological Efficiency, 1983 (United States=1)Bangladesh 0.03Thailand 0.17Hong Kong 0.40Japan 0.70West Germany 0.78Source: Trefler, American Economic Review, (December 1995), p.1037Chapter 5The Standard Trade Model* The differences and common features of the three models developed in previous chapters.··(1)different PPF(2)different PPF different RS(3)different RS different P C/P F trade* A more general trade model: the models we have studied may be viewed as special cases.·different PPF?(1)Home’s relative labor productivity of cloth is higher than Foreign’sOr (2)Q C=Q C(K,L C), Q F=Q F(T,L F). Home has more capital while Foreign has more land.Or (3)Home is labor-abundant and cloth is labor-intensive, while …·different Pc/P F?At any given Pc/P F, (Q C/Q F)>(Q C*/Q F*), RS lies to the right of RS*, that is (P C/P F)H<(P C/P F)F。
Hummels&Klenow
The Variety and Quality of a Nation’s ExportsBy D AVID H UMMELS AND P ETER J.K LENOW*Large economies export more in absolute terms than do small economies.We use data on shipments by126exporting countries to59importing countries in5,000 product categories to answer the question:How?Do big economies export larger quantities of each good(the intensive margin),a wider set of goods(the extensive margin),or higher-quality goods?Wefind that the extensive margin accounts for around60percent of the greater exports of larger economies.Within categories, richer countries export higher quantities at modestly higher prices.We compare thesefindings to some workhorse trade models.Models with Armington national product differentiation have no extensive margin,and incorrectly predict lower prices for the exports of larger economies.Models with Krugmanfirm-level product differentiation do feature a prominent extensive margin,but overpredict the rate at which variety responds to exporter size.Models with quality differentiation,mean-while,can match the price facts.Finally,models withfixed costs of exporting to a given market might explain the tendency of larger economies to export a given product to more countries.(JEL F12,F43)Virtually every theory of international trade predicts that a larger economy will export more in absolute terms than a smaller economy. Trade theories differ,however,in their predic-tions about how larger economies export more. Models that assume Paul S.Armington’s(1969) national differentiation emphasize the intensive margin:an economy twice the size of another will export twice as much but will not export a wider variety of goods.Monopolistic competi-tion models in the vein of Paul R.Krugman (1981)stress the extensive margin:economies twice the size will produce and export twice the range of goods.Vertical differentiation models, such as Harry Flam and Elhanan Helpman (1987)and Gene M.Grossman and Helpman (1991),feature a quality margin,namely richer countries produce and export higher-quality goods.These divergent predictions imply very dif-ferent consequences for welfare.If larger econ-omies intensively export more of each variety, the prices of their national varieties should be lower on the world market.In large-scale Com-putable General Equilibrium(CGE)models with distinct national varieties,the simulated welfare changes associated with trade liberal-ization are dominated by such terms-of-trade effects(see Drusilla K.Brown,1987).In Daron Acemoglu and Jaume Ventura(2002),these effects prevent real per capita incomes from diverging across countries with differing invest-ment rates.These authors argue that richer countries face lower export prices,and that this is the critical force maintaining a stationary world income distribution.1To the extent larger economies export a wider array of goods or export higher-quality goods, lower export prices are no longer a necessary*Hummels:Krannert School of Management,Purdue University,403West State Street,West Lafayette,IN47907 and National Bureau of Economic Research(e-mail: hummels@);Klenow:Department of Economics,Stanford University,579Serra Mall,Stanford, CA94305and National Bureau of Economic Research (e-mail:klenow@).We are grateful to Oleksiy Kryvtsov and Volodymyr Lugovskyy for excellent research assistance,and to the Purdue University Center for Interna-tional Business and Research for funding data purchases.Hummels acknowledges the assistance of the National Sci-ence Foundation(Grant0318242).We thank Mark Bils, Russell Cooper,Eduardo Engel,Thomas Hertel,Russell Hillberry,Tom Holmes,Valerie Ramey,Richard Rogerson, and three anonymous referees for helpful comments.1Donald R.Davis and David E.Weinstein(2002)build on the Acemoglu and Ventura model in estimating terms-of-trade-driven welfare losses to U.S.natives from in-migration.704consequence of size.Rather than sliding down world demand curves for each variety,bigger economies may export more varieties to more countries.Or they may export higher-quality goods at higher prices.If variety and quality margins dominate,then growth and develop-ment economists must rely on other forces—such as technology diffusion and diminishing returns to capital—to tether the incomes of high-and low-investment economies.Further-more,the welfare effects of trade liberalization could be very different than is typically found in many CGE models.In this paper we use highly detailed1995 United Nations data on exports to assess the importance of the extensive,intensive,and quality margins in trade.The data cover exports from126countries to each of59importers in over5,000six-digit product categories.To check robustness we also examine exports by 124countries to the United States in1995in over13,000ten-digit product categories.We decompose a nation’s exports into contributions from intensive versus extensive margins,and further decompose the intensive margin into price and quantity components.We then relate each margin to country size(PPP GDP)as well as to its components:workers,and GDP per worker.Of special interest are the extensive and qual-ity margins.There are many possible ways to define the extensive margin(counting catego-ries exported,counting categories over a certain size,weighting categories in various ways).We measure the extensive margin in a manner con-sistent with consumer price theory by adapting the methodology in Robert C.Feenstra(1994), which appropriately weights categories of goods by their overall importance in exports to a given country.The quality margin is not di-rectly observable but can be inferred by exam-ining projections of price and quantity on GDP and its components.That is,if large exporters systematically sell high quantities at high prices,this is consistent with these exporters producing higher-quality goods.We also show alternatively how to interpret the projections of price and quantity in terms of unmeasured, within-category variety.Ourfindings are as follows.The extensive margin accounts for about60percent of the greater exports of larger economies.The inten-sive margins are dominated by higher quantities of each good rather than higher unit prices. Richer countries export higher quantities of each good at modestly higher prices,consistent with higher quality.Countries with more work-ers export higher quantities of each good,but not at higher prices.These patterns hold for both the U.N.data with broad geographic cov-erage,and U.S.data with more detailed product coverage.The large extensive margins are inconsistent with Armington models,which have no exten-sive margin and imply that larger economies face lower export prices.In contrast,Krugman-style models withfirm-level product differenti-ation predict that larger economies will produce and export more varieties,consistent with the large extensive margins wefind(assuming a strictly increasing relationship between variet-ies produced and varieties exported).However, these models predict that variety will expand in proportion to exporter size,which overstates the size of the observable extensive margin in the data.Further,the Krugman model predicts that a country will export to all markets if it exports to any markets in a category,a prediction strik-ingly at odds with the evidence.Countries typ-ically export to a strict subset of markets,with larger economies exporting to decidedly more markets.This suggests thatfixed costs of ex-porting a given product to a given market,as modeled by Paul Romer(1994),may be important.Our investigation builds on the empirical work of many predecessors.Feenstra(1994) applied his method to U.S.imports of six man-ufactured goods and found evidence of substan-tial import variety growth.Michael Funke and Ralf Ruhwedel(2001)found that the variety of both exports and imports are positively corre-lated with per capita income across19OECD countries.Keith Head and John Ries(2001) looked for home-market effects in U.S.and Canadian trade in order empirically to distin-guish increasing returns and national product differentiation models.They found the evidence mostly consistent with national product differ-entiation.By comparison,we examine model implications for extensive(increasing returns) versus intensive(national product differentia-tion)margins,along with price and quantity effects that each implies.Peter K.Schott(2004)705VOL.95NO.3HUMMELS AND KLENOW:THE VARIETY AND QUALITY OF A NATION’S EXPORTSfound that richer countries export to the U.S.at higher unit prices within narrow categories. Countries more abundant in physical and hu-man capital likewise export a given variety at higher unit prices.Like Schott,we use data on export prices in narrow categories for countries of differing income levels.Unlike his study,we examine a broad range of importers and use quantity data along with price data to extract information about quality differences.The rest of the paper proceeds as follows.In Section I we briefly outline the predictions of some trade models for the various margins.We discuss the data we use in Section II,and this guides how we define the extensive and inten-sive margins(and the latter’s price and quantity components)in Section III.In Section IV we present our empiricalfindings,and in Section V we offer conclusions and possible directions for future work.I.Export Margins in Various ModelsIn Table1we summarize what four trade models predict for the size of the intensive and extensive margins,and for the price and quan-tity components of the intensive margin.In all of these models,exporter variation in workers and productivity will cause variation in the quantity of output and exports,but along differ-ent margins.The predictions for the intensive and extensive margins are stark and well known,but the price and quantity variations within the intensive margin are more subtle.In the exposition below we describe the implica-tions of the models for prices and therefore the value of output for each exporter.Then,a pro-jection of each margin on output(or on output per worker and number of workers)provides information on how well the models describe the data.To help explain the Table1entries,consider the following general environment.Consumers in country m buy from up to J countries in each of I observable categories of goods.Goods are differentiated both across categories and across producing countries within categories.For ex-ample,midsize cars and trucks may be distinct observable categories,but within a category Japanese midsize cars are differentiated from German midsize cars.For simplicity we adopt a Dixit-Stiglitz formulation with a single elastic-ity of substitutionϾ1between goods in different categories and goods from different countries.Consumers maximize utility given by(1)U mϭͫjϭ1Jiϭ1I Q jmi N jmi x jmi1Ϫ1/ͬ/͑Ϫ1͒subject to(2)jϭ1Jiϭ1IN jmi p jmi x jmiՅY m.T ABLE1—M ODEL P REDICTIONS FOR E XPORT M ARGINSIntensive (px)Extensive(V)Price(p)Quantity(x)Armington10Ϫ1/(Ϫ1)/(Ϫ1)Acemoglu&VenturaY/L10Ϫ0.6 1.6L0100Krugman0100Qualitydifferentiation10Y/L10L01Notes:For discussion of each model,see Section I in the text.Entries are model predictionsfor how exports increase with respect to exporter size.A single entry indicates the sameelasticity with respect to both Y/L(GDP per worker)and L(employment).The Acemoglu andVentura price and quantity elasticities with respect to Y/L are equal toϪ1/(Ϫ1)and/(Ϫ1),but these take on the valuesϪ0.6and1.6for their case ofϭ2.6.706THE AMERICAN ECONOMIC REVIEW JUNE2005Here Q jmi is the quality of varieties exported by country j to country m in category i.2N jmi is the number of symmetric varieties exported from j to m within category i.(We assume for simplic-ity that these within-category varieties are sym-metric.)x jmi is the number of units(quantity) exported from j to m per variety in category i, and p jmi is the price of each of the units.If country m does not buy from country j in cate-gory i(say,because j does not produce any varieties in category i),then x jmiϭ0and N jmiϭ0.Y m is country m’s income.If midsize car models are an observable cat-egory,then Japan’s exporting of multiple,dif-ferentiated midsize car models to the United States would be an example of N jmiϾ1.Of course,the more disaggregated the trade data, the more cross-category variety is captured by the observable categories(the I’s).In the data section we examine the sensitivity of our results to changing levels of aggregation.And although unobserved,within-category varieties N are not directly distinguishable from quality Q,we will be able to draw some inferences about the role of each using price and quantity data.We now explain the entries in Table1.3In doing so we focus on exporter j variation that feeds into proportional variation across all mar-kets m and categories i.That is,market-specific and category-specific proportional constants are omitted.We also express all objects relative to an exporter for which the following variables are normalized to1:I,Q,N,x,p,A(productiv-ity),L(employment),and Y.We assume that A and L differ exogenously across countries.We summarize variety within and across categories as VϭNI(ϭ1in the reference country).A.ArmingtonIn Armington’s(1969)national differentia-tion model,each country produces a single va-riety in each category(V jϭ1for all j,given the normalization),so there is no extensive margin.Quality likewise does not vary across countries (Q jϭ1for all j).A country with more workers or higher productivity simply produces more of each variety(x jϭA j L j).This intensive margin results in lower prices for each variety.The effect on export prices is smaller the larger the elasticity of substitutionbetween varieties: p jϭ(A j L j)Ϫ1/.Country j’s GDP is Y jϭp j x j V jϭ(A j L j)1Ϫ1/.Taking logs and rearrang-ing,country j’s export quantities and prices can be expressed as(3)ln͑x j͒ϭϪ1ln͑Y j/L j͒ϩϪ1ln͑L j͒and(4)ln͑p j͒ϭϪ1Ϫ1ln͑Y j/L j͒ϩϪ1Ϫ1ln͑L j͒. These expressions are the basis of the price and quantity entries in thefirst row of Table1.In this Armington world,larger economies inten-sively export higher quantities at lower prices.4 Many CGE models of trade liberalization employ a modified Armington structure that differs from the stark assumptions in this base model.In particular,they employ exporter-specific weights in the utility function calibrated so that exporter prices and country size do not systematically co-vary in the cross section. These weights can be thought of as quality Q or unobserved variety N.Since the weights are fixed,however,the implications of the base Armington model still apply to time series.That is,changes in exporter size or income are pre-dicted to yield changes in output and prices as in first-differenced versions of equations(3)and (4).2We let quality enter the utility function without an exponent so that it is in“price units,”i.e.,equivalent to a lower price.This is purely a normalization.Quality is a demand shifter in(1),raising the quantity a country can export to a market at a given price.3We refer the reader to Hummels and Klenow(2002)for a more detailed exposition.4An alternative to expression(4)is ln(pj)ϭϪ1/ln(Aj)Ϫ1/ln(L j).For empirical estimation,this expres-sion would allow consistent estimation of the effect of exogenous variables.With(4),in contrast,the effect of employment on prices will be biased downward(upward in absolute terms).Higher L lowers income per worker for a given A,so controlling for Y/L requires a higher A.The coefficient on L in(4)therefore captures the effect on export prices of higher L,combined with enough higher A to keep Y/L unchanged.As we discuss below,we focus on(4) because Y/L is directly observable,whereas one must know (and quality if it varies across countries)to derive A.707VOL.95NO.3HUMMELS AND KLENOW:THE VARIETY AND QUALITY OF A NATION’S EXPORTSB.Acemoglu and Ventura Acemoglu and Ventura(2002)add endoge-nous capital accumulation and an endogenousnumber of varieties to the Armington model.They posit constant returns to capital in theproduction of each variety,and afixed laborrequirement for producing each variety.Thenumber of varieties a country produces is thenproportional to its employment(V jϭL j).A country with higher productivity(A j,broadlyconstrued to include physical capital)producesmore of each variety(x jϭA j).Higher produc-tion of each variety translates into lower prices for each variety:p jϭ(A j)Ϫ1/.Country j’s GDP is Y jϭp j x j V jϭ(A j)1Ϫ1/L j.Greater Y/L,but not greater L,is associated with producing higher quantities of each variety and selling them at lower unit prices:(5)ln͑x j͒ϭϪ1ln͑Y j/L j͒and(6)ln͑p j͒ϭϪ1Ϫ1ln͑Y j/L j͒.The second row of Table1summarizes this model’s predictions.C.KrugmanKrugman(1979,1980,1981)modeled coun-tries as producing an endogenous number of varieties.5Withfixed output costs of producing each variety,the number of varieties produced in a country is proportional to the size of the economy(V jϭY jϭA j L j).In this simplest Krugman world,all countries export the same quantity per variety(x jϭ1for all j)and exportat the same unit prices(p jϭ1for all j).Neither unit prices nor quantity per variety vary with GDP per worker or the number of workers. These results are stated in the third row of Ta-ble1.The Krugman model has the property that, conditional on producing a variety,a country exports this variety to all other markets.A cor-ollary is that,conditional on exporting in a category,a country exports in this category to all other countries.In models withfixed costs of exporting to each market,such as Romer (1994),a country may instead export to a strict subset of markets,or even to no markets at all despite producing in the category.When we discuss our empiricalfindings in Section IV below,we will present evidence on export des-tinations to address this issue.D.Quality Differentiation Suppose quality varies across countries(Q j differs across j)but productivity and variety do not(A jϭ1and V jϭ1for all j).Countries withmore workers produce more of each variety (x jϭL j).A country’s unit prices reflect both the level of employment and the level of quality: p jϭQ j(L j)Ϫ1/.GDP is Y jϭQ j(L j)1Ϫ1/.Also, Y j/L jϭQ j(L j)Ϫ1/ϭp j.Quantity per variety should positively project on exporter employ-ment but be unrelated to exporter GDP per worker;prices for varieties should project pos-itively on GDP per worker but be unrelated to employment.These results are shown in the final row of Table1.More generally,we can use consumerfirst-order conditions from(1)and(2)to express quality and within-category variety in terms of the observed prices and quantities and the elas-ticity of substitution between varieties:(7)ln͑Q j͒ϩ1ln͑N j͒ϭln͑p j͒ϩ1ln͑N j x j͒. Note that the observed quantities per category are actually Nx,rather than the theoretically ideal x.Also note that quality and within-category variety are isomorphic(up to a scalar) in this expression.We return to this issue when discussing the empirical results.II.Data DescriptionWe draw export data from two sources.We use worldwide data from the United Nations Confer-ence on Trade and Development(UNCTAD) Trade Analysis and Information System (TRAINS)CD-ROM for1995.The TRAINS project combines bilateral import data collected5See also Wilfred J.Ethier(1979,1982).708THE AMERICAN ECONOMIC REVIEW JUNE2005by the national statistical agencies of76import-ing countries,covering all exporting countries (227in1995).The data are reported in the Harmonized System(HS)classification code at the six-digit level,or5,017goods,and include shipment values and quantities.For a subset of these countries(126of the227exporters and59 of the76importers),we have matching employ-ment and GDP data(discussed below).The59 importers represent the vast majority of world imports,so total shipments for each exporter reported in TRAINS closely approximate worldwide shipments for that exporter.Our calculation of the extensive margin may be sensitive to the level of aggregation at which we measure exports.That is,a country may export total variety VϭNI,but only categories I are observable.As data become more aggre-gated,variety shifts from the observable I to the unobservable within-category N.For example, were we to use the output data available in internationally comparable form at roughly the two-digit level,we wouldfind that most coun-tries produce and export in all sectors.6We would then obtain much smaller extensive mar-gins,with most variety differences relegated to the intensive margin.By using more detailed export data with5,017six-digit HS categories, we can do a better job of assigning variety differences to the extensive margin.We also use U.S.data with more product detail from the“U.S.Imports of Merchandise”CD-ROM for1995,published by the U.S.Bu-reau of the Census.The data are drawn from electronically submitted customs forms that re-port the country of origin,value,quantity, freight paid,duties paid,and HS code for each shipment entering the United States.The ten-digit HS scheme includes13,386highly de-tailed goods categories.The data include all countries shipping to the United States,a total of222in1995.We have data on employment and output in1995for124of these exporters.7 In both datasets,we measure prices as unit values(value/quantity).Quantity(and therefore price)data are missing for approximately16 percent of U.S.observations and18percent of worldwide observations for1995.8When the U.S.data include multiple shipments from an exporter in a ten-digit category,we aggregate values and quantities.The resulting prices are quantity-weighted averages of prices found within shipments from that exporter category. Data on national employment and GDP at 1996international(PPP)prices come from Alan Heston et al.(2002).We use PPP GDP,as opposed to GDP at current market exchange rates,to avoid any mechanical association be-tween an exporter’s price and GDP through the value of its market exchange rate.All of our empirical results are robust to using GDP val-ued at market exchange rates instead of PPP exchange rates.III.Decomposition MethodologyWe now construct empirical counterparts to the intensive margin(px),the category exten-sive margin(I),and the price(p)and quantity (x)components of the intensive margin.To do so,we adapt Feenstra’s(1994)methodology for incorporating new varieties into a country’s im-port price index when preferences take the form of our equation(1).Feenstra shows that the import price index is effectively lowered when the set of goods expands.Instead of comparing varieties imported over time,we compare varieties imported from dif-ferent exporters at a point in time.In this case, comparing export prices for country j relative to a reference country k requires an adjustment for the size of each exporter’s goods set.The ap-propriate adjustment is the extensive margin. For the case when j’s shipments to m are a6Prominent CGE models typically feature fewer than50 manufactured goods,primarily because of the dearth of output data,and therefore include no extensive margins in their analysis.The most disaggregated model we couldfindin the CGE literature is that employed by the U.S.Interna-tional Trade Commission.It has roughly500sectors,still an order of magnitude fewer than the six-digit HS codes we use.Also,its structure is fundamentally different from the models under consideration here.It has a United States versus rest-of-world focus,contains no data on rest-of-world output,and allows for no cross-country differences in varieties either in cross section or over time.7The remaining98,primarily very small or former Soviet-bloc countries,comprise only5percent of U.S.trade in1995.8The likelihood that quantity data are missing is uncor-related with aggregate employment and GDP per worker,so our analyses should not be biased by dropping these observations.709VOL.95NO.3HUMMELS AND KLENOW:THE VARIETY AND QUALITY OF A NATION’S EXPORTSsubset of k’s shipments to m,the extensive margin is defined as(8)EM jmϭ¥iʦI jmp kmi x kmi iʦIkmi kmi.This is a cross-exporter analogue of Feenstra’snew varieties adjustment to an import priceindex.I jm is the set of observable categories inwhich country j has positive exports to m,i.e.,x jmiϾ0.(In our empirical implementation,the I categories will be5,017six-digit U.N.HS product codes.)Reference country k has posi-tive exports to m in all I categories.(In ourempirical implementation,k will be rest-of-world.)EM jm equals country k’s exports to m inI jm relative to country k’s exports to m in all Icategories.The extensive margin can be thought of as aweighted count of j’s categories relative to k’scategories.If all categories are of equal impor-tance,then the extensive margin is simply thefraction of categories in which j exports to m.More generally,categories are weighted bytheir importance in k’s exports to m.An advan-tage of evaluating a category’s importance with-out reference to j’s exports is that it prevents acategory from appearing important solely be-cause j(and no other country)exports a lot to min that category.9The corresponding intensive margin com-pares nominal shipments for j and k in a com-mon set of goods.It is given by(9)IM jmϭ¥iʦI jmp jmi x jmi ¥iʦI jmp kmi x kmi.IM jm equals j’s nominal exports relative to k’s nominal exports in those categories in which j exports to m(I jm).The ratio of country j to country k exports to m equals the product of the two margins:(10)¥iϭ1Ip jmi x jmi¥iϭ1Ip kmi x kmiϭIM jm EM jm.To see a simple example of the intensive versus extensive decomposition,compare German and Belgian exports to the United States,using kϭrest-of-world for the reference country in each case.Given the size of each,it is not surprising that Germany’s exports to the United States are 6.2times larger than Belgium’s.Some of this comes through a greater number of categories shipped—Germany ships in79percent of the 5,017six-digit HS codes,while Belgium ships in51percent.Were all categories of equal weight,this would yield an extensive margin for Germany that is1.55times larger than Bel-gium’s.This leaves an intensive margin(i.e., exports per category)for Germany that is four times larger than Belgium’s.However,not all categories are of equal weight.Germany ships in categories that are a larger share of rest-of-world exports to the United States,the numer-ator in equation(8).Incorporating the weighted counts,Germany’s extensive margin is 1.65 times greater than Belgium’s,and its intensive margin is3.75times larger.We now turn to decomposing the intensive margin into price and quantity indices.Suppose that quality(Q)and within-category variety(N) vary across categories i for each importer m. This encompasses preferences that place more weight on some goods than on others.As a baseline case,assume further that quality and within-category variety do not vary by exporter. (In our empirical analysis,we will test these assumptions.)For this baseline case,Feenstra (1994)derives an exact price index for the in-tensive margin of country m’s imports from j versus k:(11)P jmϭiʦI jmͩp jmi p kmiͪw jmi.In(11),w jmi is the logarithmic mean of s jmi(the9A disadvantage is that a country may appear to havea large extensive margin because it exports a smallamount in categories in which k exports a lot.As wediscuss in the next section,we do notfind this to be thecase empirically.710THE AMERICAN ECONOMIC REVIEW JUNE2005。
中国与东盟国家的贸易潜力的分析——基于随机前沿贸易引力模型
中国对这些国家的出口成本降低，电子商务发展在国际贸易领域存在贸易成本效应。
因此，要建设21世纪海上丝绸之路和新丝绸之路经济带，必须加强沿线国家的互联网、移动通信等基础设施建设。
参考文献:[1]习近平.加快推进丝绸之路经济带和21世纪海上丝绸之路建设.新华网,2014.11.06.[2]Evgeniya Yushkova.Impact of ICT on trade In different technology groups:analysis and implications[J].International Economics and Economic Policy,2013,11（1）：165-177.[3]Joshua Meltaer.The internet,cross-border data flows and inter-national trade[J].Asia &the Pacific Policy Studies,2013:90-102.[4]Ricci,L.A，and F.Trionfetti.Productivity,networks,and export performance:evidence[J],2012.[5]Haluk Demirkan,Michael Goul,Robert,J.Kauffman and David M.Weber.Does distance matter?The influence of ICT on bilateral trade flows[J].2009.[6]Seyed Reza Miraskari,Noorollah Salehi Asfiji,Seyed Abdolkarim Siadat,Seyed Ali Mirasgari.The effect of the internet on trade flows[J].Economics and Finance Review，2011（6）:100-106.[7]李子,杨坚争.跨境电子商务对进出口贸易影响的实证分析[J].中国发展,2014,14(05):37-42.[8]Faqin Lin.Estimating the effect of the internet on international trade[J].Journal of International Trade and Economic,2014:409-428.[9]Fink C,Mattoo A,Neagu I C.Assessing the impact of communication costs on international trade[J].Journal of International E-conomics，2005,67（2）：428-445.[10]Freund Caroline,Diana Weinhold.The effect of the internet on international trade[J].Journal of International Economics,2004,62:169-171.[11]Wallesten,S &Clarke,G.Has the internet increased trade?Evidence from industrial and developing countries [J].World Bank Policy Research,Working Paper，2004,3215.[12]George R.G.Clarke.Has the internet increased exports for firms from low and middle-income countries[J].Information Economics and Policy,2008,20:16-37.[13]黄银瑶.电子商务下国际贸易的效应分析[J].新经济,2015(17):59-60.[14]孙瑾,杨英俊.中国与“一带一路”主要国家贸易成本的测度与影响因素研究[J].国际贸易问题,2016(05):94-103.[15]Tinbergen J.Les données fondamentales d'un plan régional.Rev.Tiers Monde 1962,3,329-336.作者简介：孙如玉（1998-），女，辽宁铁岭人，本科生，研究方向:贸易经济；石宁（1994-），女，辽宁铁岭人，硕士研究生，研究方向：贸易经济；刘玉丰（1995-），女，辽宁本溪人，硕士研究生，研究方向：贸易经济中国与东盟国家的贸易潜力的分析———基于随机前沿贸易引力模型■郑怡馨西南大学西塔学院摘要：由于近期新冠疫情的暴发，我国同世界其他国家的贸易受到不同程度的影响，但是随着中国-东盟自由贸易区建设的推进，东盟将成为我国日后外贸的主要增长点。
国际经济学第章规模经济、不完全竞争与国际贸易
四、垄断竞争模型
垄断竞争的概念：许多由出售相似而不相 同的产品的企业构成的市场结构。
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四、垄断竞争模型
垄断竞争市场的特征
➢ 产品差别：similar but not identical ➢ 每个厂商把竞争对手的价格作为既定价格——即
不考虑自己的价格对其他厂商价格的影响。
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四、垄断竞争模型
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二、规模经济和市场结构
规模经济
内部规模经济 外部规模经济
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二、规模经济和市场结构
内部规模经济（internal economies of scale）：指 单位产品成本取决于单个厂商的规模，随着单个 厂商规模的扩大，单位产品的生产成本逐渐下降。 外部规模经济（external economies of scale）： 指单位产品的成本取决于所在行业的生产规模， 随着所在行业规模的扩大，单位产品的生产成本 逐渐下降。
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二、规模经济和市场结构
一个只存在外部规模经济的行业，一般由 许多相对较小的厂商构成，且处于完全竞 争的状态。 在一个只存在内部规模经济的行业，大厂 商比小厂商更具有成本优势，则形成了不 完全竞争的市场结构。
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相关问题
分析下列四例，解释每例中是外部规模经济情 形还是内部规模经济 a. 美国印第安纳州艾克哈特的十几家工厂生产了 美国大多数的管乐器。 b. 在美国销售的所有本田车要么是从日本进口的， 要么是在俄亥俄州的玛丽斯维利生产的。 c. 欧洲惟一的大型客机生产商——空中客车公司 的所有飞机都在法国土伦组装。 d. 康涅狄格州的哈特福特成为美国东北部的保险 业中心。
MR = P - Q / B 则有 MR = P - Q /（ S*b） 利润最大化条件：P = c + Q /（ S*b）
列昂惕夫反论及其解释
企业战略、结构和竞争对手 — 指企业在 一个国家里的基础、组织和管理形态， 以及国内市场的竞争的表现，包括公司 建立、组织和管理的环境和国内竞争的 性质。 国家竞争优势来自于对它们的选择和搭 配、取决于国内的竞争程度，激烈的国 内竞争是创造和保持竞争优势最有利的 刺激因素。
需求偏好相似说 （Theory of Demand Preference Similarity) 该理论创始人林德认 为,人均收入水平越接近的国家,其消费 偏好和需求结构越相似,产品的相互适应 性越强,贸易交往也就越密切。对此类产 品，一国可以通过规模经济收益递增获 得产量增加,生产成本递减的比较优势, 来满足国家间对产品的需求。 人均收入水平存在较大差距是产业内 贸易发展潜在的障碍。
国家会获得技术领先优势；什么样的国家及其厂商可获 得规模经济优势？为什么某种产品在国内市场很小或发 展缓慢的情况下，仍能成为商界领先者？）。
迈克尔· 波特在其著作《 国家竞争优势 》 （1990）中指出：“一个国家的竞争优势 就是企业与行业的竞争优势，一国兴衰 的根本原因在于它能否在国际市场中取 得竞争优势,而竞争优势形成的关键在于 能否使主导产业具有优势，产业的竞争 优势又源于企业是否具有创新机制”。
生产要素（factor conditions）
生产要素分为：基本要素和高级要素（现代化基 础设 施、高素质人力资源、高技术）；
在过去，基本要素在许多行业对企业的竞争 优势居有决定性的影响，但现在，其重要性日益 减弱，取而代之的是高级要素。 高级要素的优势是企业国际竞争力在未来可 持续发展的源泉（丹麦的胰岛素、荷兰的花卉，以色
机遇（opportunities）包括重要发明、重大技术变 化、投入成本剧变(如石油危机时）, 外汇汇率 的重要变化、突然出现的世界或地区需求、外 国政府的政治决定和战争等。