1、International Economics theory and policy,Paul R. Krugman Maurice Obstfeld,Chaper 3 Resources, Comparative Advantage, and Income Distribution,A Model of a Two-Factor Economy:Prices and Production Effects of International Trade Between Two-Factor Economies The Political Economy of Trade: A Preliminar
2、y View Empirical Evidence on the Heckscher-Ohlin Model Summary,1. A Two-Factor Economy Model,MODEL: two countries A and B, produces two goods X and Y, with two mobile factors of production M and N. Assumes two goods are cloth (C) and food (F), two two mobile factors of land (T) and labor (L). Defini
3、tion: A countrys land productivity of cloth shows by TC, labor productivity LC; the land productivity of food by TF, labor productivity LF; a countrys aggregate supply of labor is L, the total land supply is T.,Production Possibility Frontier,The production possibility frontier without factor substi
4、tution:,Quantity of food, QF,Quantity of cloth, QC,L/LF,T/TF,L/LC,T/TC,Labor constraint,Land constraint,Production Possibility Frontier,The production possibility frontier with factor substitution: WHY?,Quantity of food, QF,Quantity of cloth, QC,PPF,PPF and Diminishing Marginal Returns,生产可能性边界是一条凹函数
5、曲线，表明了各部门投入要素的边际报酬递减规律； 以劳动为例: 生产可能性边界的斜率为：-MPLF/MPLC.,Prices and Production,Isovalue line(budget constraint line) and PPF:,Quantity of food, QF,Quantity of cloth, QC,PPF,Isovalue lines,Q,Factor Input of Unit Product,Input possibilities in food production:,Land input,Labor input,Input combinations p
6、er unit of food,How to Choose the Input?,It will depend on the ralative cost of two factors, that is the factor prices. Suppose the labors wage rate is w, and the lands rent rate is r. the two factors price is w/r.,FF Curve and CC Curve,Wage-rental ratio，w/r,CC,FF,Land-labor ratio，T/L,FF Curve and C
7、C Curve,The FF curve shows the relationship of relative prices and relative quantities used in foods production. The CC curve shows the relationship of relative prices and relative quantities used in production of cloth. Why are the two curves different with each other?,Food-Intensive and Cloth-Inte
8、nsive,在要素价格比一定的情况下，不同的产品生产所需要的要素投入组合是不一样的，此时更多地需要某种生产要素的产品称为这种要素生产密集型产品(XX-intensive goods)。 So with the figure showed above, the food is land-intensive and the cloth is labor-intensive.,Food-Intensive and Cloth-Intensive,Note: Can a good be both factors-intensive? Answers: NO. One good can be only
9、one factor-intensive. In reality, some goods are treated as different types of factor-intensive products. Why?,Factor Prices and Goods Prices,The factors relative prices and the goods relative prices are of one-to-one relationship: (Why is SS curve concave?),Relative price of goods，PC/PF,SS,Wage-ren
10、tal ratio，w/r,Goods Prices and Factor Input,Still a one-to-one relationship:(WHY?),CC,FF,SS,Relative price of goods，PC/PF,Land-labor ratio，T/L,Wage-rental ratio，w/r,Summary 1:,布的相对价格增长会导致工人相对收入的增加。 布的相对价格的增长会导致两种商品衡量的实际工资的上涨，同时降低实际租金，即增加了工人的购买力而降低了土地所有者的购买力。 为什么？ 要素所得等于该要素边际产出的支付。,Resources and Outp
11、ut,Knowing the relationship of commodity prices, factor supply and goods output, we can build up a two-factor economic model:,C,F,生产布的劳动量,生产粮食的劳动量,生产布的土地量,生产粮食的土地量,An Increase in the Supply of Land,An increase in the supply of land will increase the food production and reduce the cloth production. W
12、hats more, the increase rate of food production will be beyond the increase rate of land supply. P59,Resource Changes and Production Possibility,土地增加会引起生产可能性边界向外扩展了，使得资源在不同生产部门重新分配。 Summary 2: 罗勃津斯基效应(Rybczynski effect)：资源供给的变动对生产可能性具有偏向性效应，这也是理解资源差异如何导致国际贸易的关键。,2. Effects of International Trade Bet
13、ween Two-Factor Economies,Assume every things of two countries are equal, except the situation in resources. Home country is labor-abundant and Foreign is land-abundant. (Abundance is a relative quantity) Note: The two countries consumer preferences and production functions are the same, that the re
14、lative demand and production technology are the same. How about these conditions are different?,Relative Prices and the Pattern of Trade,The internation trade between two countries will bring the relative prices of the goods to converge.,Relative Price，PC/PF,Relative Quantity，（QC+QC*）/（QF+QF*）,RD,RS
15、W,RS,RS*,Budget Constraint,Budget constraint equation: DF-QF=(PC/PF) (QC-DC) DF-QF is the economys food imports, and QC-DC is the economys cloth exports.,Summary 2:,各国倾向于出口国内充裕资源密集型的产品。 Countries tend to export goods whose production is intensive in factors with which they are abundantly endowed.,Tr
16、ade and the Distribution of Income,贸易导致了相对价格的趋同，而相对价格的变动对土地和劳动的所有者的收入产生影响。 本国布的相对价格上升会引起工人收入的购买力上升而土地所有者收入的购买力下降，同时，外国粮食的相对价格上升引起土地所有者收入的购买力上升而工人收入的购买力下降。,Further thinking: China and U.S.A.,美国高技术工人相对充裕，低技术工人稀缺，从而贸易出口多为高技术工人生产的产品。低技术工人的生活状况本就不好，世界商品价格的趋同使得美国低技术工人收入的购买力更低，从而引发贸易保护和贸易争端。 中国的情况如何？请大家谈谈自
17、己的所见所闻，是否与理论的结论相一致？,Factor-Price Equalization,按照商品相对价格和资源投入的一一对应关系，世界贸易使得商品相对价格的均等化，必然引起世界各国间要素价格的均等化。（斯托尔珀萨缪尔森定理） Why are the reality and theory results so different? 1. The two countries are not necessarily producing two commodities at the same time; 2. Different levels of production technology wi
18、ll have different production functions; 3. In reality, the relative prices of goods in different countries are not the same, because the existence of transaction costs in trade.,3.The Political Economy of Trade: A Preliminary View,Questions: In what sense can we even talk about gains from trade when
19、 some people lose? Given the fact that some people lose from trade, what should the government do? What are government likely to do in practice?,The Gains from Trade,贸易净所得不是看谁在贸易中感到更满足或感到更沮丧，而是看贸易是否会使得贸易所得补偿贸易损失而有余。 用预算约束线和生产可能性边界可以看出不论是单要素还是双要素模型条件下，贸易都会有净所得。,Optimal Trade Policy,当国民的收入和偏好是相同时，自由贸易
20、自然成为政府提高国民福利的一项重要举措。 但当国民的仿好不同时，政府就要权衡贸易会使一部分人有所得而使另一部分人有所失所带来的福利变化。,Income Distribution and Trade Policy,贸易受损者往往会比贸易受益者更能游说政府而令政府对外采取贸易限制或贸易保护。 在政府政策影响因素方面，既得利益群体强于弱势群体，少数人强于多数人，受害者强于受益者。,4. Empirical Evidence on the Heckscher-Ohlin Model,Tests on U.S. Data 里昂惕夫悖论(Leontief Paradox) ：里昂惕夫通过对第二次世界大战后
21、25年的实证分析，发现作为资本充裕国的美国，其出口产品的资本密集程度却低于其进口产品的资本密集程度。这成为和要素禀赋理论对立的最重要的一个证据。,Explnation of Leontiefs Paradox,一种投入可能孕含多种要素，要界定某一种投入是何种要素密集型的有时十分困难。 将投入重新划分为何种生产要素密集型的，使之具有一定的单一特征，这往往比研究经济现象本身更难。,Tests on Global Data,有三分之二的生产要素在不到70%的范围内是以要素禀赋理论的论断方式进行贸易的。这也表明要素禀赋理论还不能完全解释国际贸易的运行规律。,Teats on North-South Trade,实证结果比较认同至少在解释南北贸易时，要素禀赋理论是比较有效的。,The Case of the Missing Trade,跳过商品贸易而直接看作是要素贸易，情况会比间接通过商品贸易来分析更为准确。这可以将商品分割为不同要素的总和而实证考察要素交换的情况，这样一来，实际要素交换量将远小于H-O模型估计的数量。,End of Chapter 3,
