二章劳动生产率和比较优势李嘉图模型.ppt

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1、二章劳动生产率和比较优势李嘉图模型 Still waters run deep.流静水深流静水深,人静心深人静心深 Where there is life,there is hope。有生命必有希望。有生命必有希望国家之间进行国际贸易基于两个基本的原因：一是差异：气候、资源、技术等二是生产中的规模经济 scale economies(规模经济)李嘉图模型（The Ricardian model）基于各国间技术差异技术差异反映在劳动生产率上（productivity of labor）.导论2美国情人节的例子。On Valentines Day the U.S.demand for roses

2、is about 10 million（100万支）roses.美国在冬天种植玫瑰比较困难：加热的温室其投入的资源是比较多的（能源、劳动力、资本）这些资源也可以用来生产其他商品，如计算机.2-1 比较优势的概念3Opportunity Cost（机会成本）The opportunity cost of roses（A)in terms of computers（B)is the number of computers（B)that could be produced with the same resources as a given number of roses（A).以商品B衡量生产商品

3、A的机会成本，就是生产一定数量商品A所消耗的资源所能生产商品B的数量。例：生产1000万支玫瑰的机会成本是10万台计算机；而生产10万计算机的机会成本是1000万支玫瑰。更为准确地说，生产一支玫瑰的机会成本是？台计算机；而生产一台计算机的机会成本是？支玫瑰。Comparative Advantage（比较优势）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 tha

4、t country than it is in other countries.如果一国生产一种产品的机会成本（用其他商品衡量）低于其他国家生产该种产品的机会成本，则该国在生产此种产品上具有比较优势。4假定美国生产100支玫瑰的资源可以用来生产10万台计算机。假定在南美生产100支玫瑰的资源可以用来生产3万台计算机.这就假定南美比美国的劳动生产率更低。5如果每个美国均专业化生产机会成本更低的商品，则贸易使双方受益。在南美玫瑰的机会成本更低，而美国计算机的机会成本更低。从贸易中获利可以从双方计算机和玫瑰产量的变化得到。6Table 2-1:产量的变化7玫瑰的机会成本 计算机的机会成本United

5、 States0.01100South America0.0033338The example in Table 2-1 illustrates the principle of comparative advantage:If each country exports the goods in which it has comparative advantage(lower opportunity costs),then all countries can in principle gain from trade.What determines comparative advantage?A

6、nswering this question would help us understand how country differences determine the pattern of trade(which goods a country exports).（Ricardian Model）92-2 A One-Factor EconomyAssume that we are dealing with an economy(which we call Home).In this economy（五个假定条件）Labor is the only factor of production

7、.（一种要素:劳动力）Only two goods(say wine and cheese)are produced.（两种商品）The supply of labor is fixed in each country.（劳动要素供应不变）The productivity of labor in each good is fixed.（劳动生产率不变）Perfect competition prevails in all markets.（完全竞争）10The constant labor productivity is modeled with the specification of un

8、it labor requirements:The unit labor requirement（单位产品劳动投入）is the number of hours of labor required to produce one unit of output.（单位：人小时，person-hours）Denote with aLW the unit labor requirement for wine(e.g.if aLW=2,then one needs 2 hours of labor to produce one gallon of wine).Denote with aLC the un

9、it labor requirement for cheese(e.g.if aLC=1,then one needs 1 hour of labor to produce a pound of cheese).总资源为劳动力（L）The economys total resources are defined as L,the total labor supply(e.g.if L=120,then this economy is endowed with 120 hours of labor or 120 workers).11Production Possibilities(生产能力)T

10、he production possibility frontier(PPF，生产可能性边界)of an economy shows the maximum amount of a good(say wine)that can be produced for any given amount of another(say cheese),and vice versa.（生产可能性边界：给定一种产品产量时，能够生产另外一种产品的最大可能产量）The PPF of our economy is given by the following equation:aLCQC+aLWQW L (2-1)F

11、rom our previous example,we get:QC+2QW 12012L/aLWL/aLCFigure 2-1:Homes Production Possibility FrontierAbsolute value of slope equalsopportunity cost of cheese interms of wineFPHome wine production,QW,in gallonsHome cheese production,QC,in pounds13Relative Prices and SupplyThe particular amounts of e

12、ach good produced are determined by prices.The relative price(相对价格)of good X(cheese)in terms of good Y(wine)is the amount of good Y(wine)that can be exchanged for one unit of good X(cheese).Examples of relative prices:If a price of a can of Coke is$0.5,then the relative price of Coke is the amount o

13、f$that can be exchanged for one unit of Coke,which is 0.5.The relative price of a$in terms of Coke is 2 cans of Coke per dollar.14Denote with PC the dollar price of cheese and with PW the dollar price of wine.Denote with wW the dollar wage in the wine industry and with wC the dollar wage in the chee

14、se industry.(工资率)：葡萄酒部门工资率为PW/aW Then under perfect competition,the non-negative profit condition implies:If PW/aW wW,then there is no production of QW.If PW/aW=wW,then there is production of QW.If PC/aC wC,then there is no production of QC.If PC/aC=wC,then there is production of QC.15The above rela

15、tions imply that if the relative price of cheese(PC/PW)exceeds its opportunity cost(aLC/aLW),then the economy will specialize in the production of cheese.（当奶酪的相对价格大于其机会成本时，该国才会专业化生产奶酪）In the absence of trade,both goods are produced,and therefore PC/PW=aLC/aLW.162-3 Trade in a One-Factor WorldAssumpt

16、ions of the model（模型假设）:1.There are two countries in the world(Home and Foreign).2.Each of the two countries produces two goods(say wine and cheese).3.Labor is the only factor of production(生产要素).4.The supply of labor is fixed in each country.5.The productivity of labor in each good is fixed.6.Labor

17、 is not mobile across the two countries.7.Perfect competition prevails in all markets.8.All variables with an asterisk refer to the Foreign country.17Absolute Advantage(绝对优势)A country has an absolute advantage in a production of a good if it has a lower unit labor requirement than the foreign countr

18、y in this good.即，当一个国家能以少于其他国家的劳动投入生产出同样单位商品时，则该国在生产此商品上具有绝对优势。Assume that aLC a*LC and aLW a*LWThis assumption implies that Home has an absolute advantage in the production of both goods.Another way to see this is to notice that Home is more productive in the production of both goods than Foreign.E

19、ven if Home has an absolute advantage in both goods,beneficial trade is possible.The pattern of trade will be determined by the concept of comparative advantage.18Comparative Advantage假设本国用酒衡量的奶酪的机会成本小于外国（Assume that aLC/aLW a*LC/a*LW）(2-2)This assumption implies that the opportunity cost of cheese

20、in terms of wine is lower in Home than it is in Foreign.Home has a comparative advantage in cheese and will export it to Foreign in exchange for wine.19F*P*L*/a*LWL*/a*LC外国葡萄酒的产量外国葡萄酒的产量 Q*W,in gallons外国奶酪的产量外国奶酪的产量,Q*C,in pounds+1图图 2-2:外国的生产只要能性曲线20Determining the Relative Price After TradeWhat de

21、termines the relative price(e.g.,PC/PW)after trade?To answer this question we have to define the relative supply and relative demand for cheese in the world as a whole.The relative supply of cheese equals the total quantity of cheese supplied by both countries at each given relative price divided by

22、 the total quantity of wine supplied,(QC+Q*C)/(QW+Q*W).The relative demand of cheese in the world is a similar concept.212RDRD1QaLC/aLWa*LC/a*LWRSFigure 2-3:World Relative Supply and DemandRelative priceof cheese,PC/PWRelative quantityof cheese,QC+Q*C QW+Q*WL/aLCL*/a*LW22The Gains from TradeIf count

23、ries specialize according to their comparative advantage,they all gain from this specialization and trade.We will demonstrate these gains from trade in two ways.First,we can think of trade as a new way of producing goods and services(that is,a new technology).23Another way to see the gains from trad

24、e is to consider how trade affects the consumption in each of the two countries.The consumption possibility frontier states the maximum amount of consumption of a good a country can obtain for any given amount of the other commodity.In the absence of trade,the consumption possibility curve is the sa

25、me as the production possibility curve.Trade enlarges the consumption possibility for each of the two countries.24Figure 2-4:Trade Expands Consumption Possibilities消费可能的扩张TFPT*P*F*(a)Home(b)ForeignQuantityof wine,QWQuantityof cheese,QCQuantityof wine,Q*WQuantityof cheese,Q*C25A Numerical ExampleThe

26、following table describes the technology of the two counties:Table 2-2:Unit Labor Requirements26The previous numerical example implies that:aLC/aLW=1/2 a*LC/a*LW=2In world equilibrium,the relative price of cheese must lie between these values.Assume that Pc/PW=1 gallon of wine per pound of cheese.Bo

27、th countries will specialize and gain from this specialization.Consider Home,which can transform wine to cheese by either producing it internally or by producing cheese and then trading the cheese for wine.27Home can use one hour of labor to produce 1/aLW=1/2 gallon of wine if it does not trade.Alte

28、rnatively,it can use one hour of labor to produce 1/aLC=1 pound of cheese,sell this amount to Foreign,and obtain 1 gallon of wine.28In the absence of trade,Foreign can use one unit of labor to produce 1/a*LC=1/6 pound of cheese using the domestic technology.Can it do better by specializing in wine a

29、nd trading wine with Home for cheese?In the presence of trade,Foreign can use one unit of labor to produce 1/a*LW=1/3 gallon of wine.Since the world price of wine is PW/PC=1 pound of cheese per gallon,Foreign can obtain 1/3 lb of cheese which is more than 1/6 lb.29Relative Wages(相对工资)Because there a

30、re technological differences between the two countries,trade in goods does not make the wages equal across the two countries.A country with absolute advantage in both goods will enjoy a higher wage after trade.30This can be illustrated with the help of a numerical example:Assume that PC=$12 and that

31、 PW=$12.Therefore,we have PC/PW =1 as in our previous example.Since Home specializes in cheese after trade,its wage will be(1/aLC)PC=(1/1)$12=$12.Since Foreign specializes in wine after trade,its wage will be(1/a*LW)PW=(1/3)$12=$4.Therefore the relative wage of Home will be$12/$4=3.Thus,the country

32、with the higher absolute advantage will enjoy a higher wage after trade.31Productivity and CompetitionMyth 1:Free trade is beneficial only if a country is strong enough to withstand foreign competition.This argument fails to recognize that trade is based on comparative not absolute advantage.The Pau

33、per Labor ArgumentMyth 2:Foreign competition is unfair and hurts other countries when it is based on low wages.Again in our example Foreign has lower wages but still benefits from trade.2-4 Misconceptions About Comparative Advantage32ExploitationMyth 3:Trade makes the workers worse off in countries

34、with lower wages.In the absence of trade these workers would be worse off.Denying the opportunity to export is to condemn poor people to continue to be poor.33Table 2-3:Changes in Wages and Unit Labor Costs34模型建立（Setting Up the Model）Both countries consume and are able to produce a large number,N,of

35、 different goods.按两国生产产品的相对劳动投入排序：a*L1/aL1 a*L2/aL2 a*L3/aL3 a*LN/aLN 相对工资与专业化（Relative Wages and Specialization）贸易模式依赖于两国的劳动工资（The pattern of trade will depend on the ratio of Home to Foreign wages.）成本最低原则选择产品进行专业化生产Goods will always be produced where it is cheapest to make them.For example,it will

36、 be cheaper to produce good i in Home if waLi w/w*.2-5 Comparative Advantage with Many Goods多产品模型中的比较优势35Table 2-4:Home and Foreign Unit Labor Requirements36哪个国家生产哪些产品Which country produces which goods?A country has a cost advantage in any good for which its relative productivity is higher than its

37、relative wage.（取决于相对工资率和相对生产效率）If,for example,w/w*=3,Home will produce apples,bananas,and caviar,while Foreign will produce only dates and enchiladas.Both countries will gain from this specialization.37Determining the Relative Wage in the Multigood Model（多产品模型中相对工资的决定）To determine relative wages in

38、a multigood economy we must look behind the relative demand for goods(i.e.,the relative derived demand).（通过相对劳动需求与供给来决定对劳动力的相对需求是根据对能生产产品推算出来的派生需求）The relative demand for Home labor depends negatively on the ratio of Home to Foreign wages.（当本国对外国的相对工资率上升时，对本国劳动的相对派生需求将减少。两个原因：一是本国生产产品价格更高，二是本国能生产的产品

39、种类减少）38310Apples8Bananas4Caviar2Dates0.75EnchiladasRDFigure 2-5:Determination of Relative WagesRSRelative wageRate,w/w*Relative quantityof labor,L/L*392-6 运输费用和非贸易品Adding Transport Costs and Nontraded Goods国际经济中，专业分工不是极端的原因有三个（There are three main reasons why specialization in the real international

40、 economy is not extreme）:1、多种要素The existence of more than one factor of production.2、贸易保护Countries sometimes protect industries from foreign competition.3、运输费用和非贸易品It is costly to transport goods and services.The result of introducing transport costs makes some goods nontraded.In some cases transpor

41、tation is virtually impossible.Example:Services such as haircuts and auto repair cannot be traded internationally.40 1975年 1985年 1995年Developedcountries 1.065 1.048 1.044America 1.066 1.047 1.037Canada 1.027 1.025 1.027Australia 1.070 1.118 1.067Japan 1.132 1.082 1.090France 1.049 1.039 1.034Germany

42、 1.041 1.028 1.028Britain 1.072 1.045 1.025Switzerland 1.026 1.010 1.01041 1975年 1985年 1995年DevelopingCountries 1.128 1.118 1.114Africa 1.120 1.126 1.120Asia 1.097 1.088 1.087Middle East 1.136 1.105 1.097western hemisphere 1.111 1.091 1.090FIF（CIF）/（FOB）422-7 Empirical Evidence on the Ricardian Mode

43、lFigure 2-6:Productivity and Exports43MacDougall(1951）Balassa(1963）Stephen S.Golub(1995)44.4546.47Reading邵润堂、张华（1999）：比较优势、竞争优势比较优势、竞争优势及国际竞争力，经济问题第及国际竞争力，经济问题第4 4期期洪银兴（1997）：从比较优势到竞争优势兼论国际贸易的比较利益理论的缺陷，经济研究第6期符正平（1999）：比较优势与竞争优势的比较比较优势与竞争优势的比较分析分析兼论新竞争经济学及其启示，国际贸易问题第8期48Question作业：P35,3，5思考：1、石油价格由劳动价值决定吗？2、中东产油国的财富来自国民的勤劳还是上帝的恩施？3、如何评价美国经济增长中知识贡献已占42%。49