2劳动生产率和比较优势：李嘉图模型.ppt

1、1,YOU ARE WELCOME !,2,International Economics,国际经济学 主讲：余道先 ,3,Chapter 2,Labor Productivity and Comparative Advantage: The Ricardian Model 劳动生产率和比较优势：李嘉图模型,4,Preview,Introduction The Concept of Comparative Advantage（比较优势） A One-Factor Economy（单一要素经济） Trade in a One-Factor World（单一要素世界的贸易） Comparative

2、 Advantage with Many Goods（多种产品的比较优势） Adding Transport Costs and Nontraded Goods（引入运输成本和非贸易品） Empirical Evidence on the Ricardian Model Summary,5,Countries engage in international trade for two basic reasons: They are different from each other in terms of climate, land, capital, labor, and technolog

3、y. They try to achieve scale economies （规模经济）in production. The Ricardian model is based on technological differences across countries. These technological differences are reflected in differences in the productivity of labor.,Introduction,6,The Ricardian model uses the concepts of opportunity cost

4、and comparative advantage.,The Concept of Comparative Advantage,7,For example，On Valentines Day the U.S. demand for roses is about 10 million roses. Growing roses in the U.S. in the winter is difficult. Heated greenhouses should be used. The costs for energy, capital, and labor are substantial. Reso

5、urces for the production of roses could be used to produce other goods, say computers.,The Concept of Comparative Advantage,8,Opportunity Cost（机会成本） The opportunity cost of roses in terms of computers is the number of computers that could be produced with the same resources as a given number of rose

6、s. Comparative Advantage（比较优势） A country has a comparative advantage in producing a goods if the opportunity cost of producing that goods in terms of other goods is lower in that country than it is in other countries. 如果一个国家在本国生产某种产品的机会成本（用其他产品来衡量）低于在其他国家生产该种产品的机会成本的话，则这个国家在该种产品的生产上具有比较优势。,The Conce

7、pt of Comparative Advantage,9,Suppose that in the U.S. 10 million roses can be produced with the same resources as 100,000 computers. Suppose also that in South America 10 million roses can be produced with the same resources as 30,000 computers. This example assumes that South American workers are

8、less productive than U.S. workers.,The Concept of Comparative Advantage,10,If each country specializes in the production of the goods with lower opportunity costs, trade can be beneficial for both countries. Roses have lower opportunity costs in South America. Computers have lower opportunity costs

9、in the U.S. The benefits from trade can be seen by considering the changes in production of roses and computers in both countries.,The Concept of Comparative Advantage,11,Table 2-1: Hypothetical Changes in Production,The Concept of Comparative Advantage,12,The example in Table 2-1 illustrates the pr

10、inciple 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.（如果每个国家都出口本国具有比较优势的商品（低的机会成本），那么每个国家都会从贸易中受益） What determines comparative advantage? Answering this question would

11、help us understand how country differences determine the pattern of trade (which goods a country exports).,The Concept of Comparative Advantage,13,A One-Factor Economy （单一要素经济）,Assume that we are dealing with an economy (which we call Home). In this economy: Labor is the only factor of production. O

12、nly two goods (say wine and cheese) are produced. The supply of labor is fixed in each country. The productivity of labor in each goods is fixed. Perfect competition prevails in all markets.,14,The technology of Homes economy can be summarized by labor productivity in each industry, expressed in ter

13、ms of unit labor requirements: The unit labor requirement is the number of hours of labor required to produce one unit of output. 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 unit labor requi

14、rement for cheese (e.g. if aLC = 1, then one needs 1 hour of labor to produce a pound of cheese).,A One-Factor Economy,15,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.,A One-Factor Economy,

15、16,Production Possibilities The production possibility frontier (PPF) （生产可能性边界）of an economy shows the maximum amount of a goods (say wine) that can be produced for any given amount of another (say cheese), and vice versa. Or illustrates the different mixes of goods the economy can produce. The PPF

16、of our economy is given by the following equation: aLCQC + aLWQW = L (2-1) From our previous example, we get: QC + 2QW = 120,A One-Factor Economy,17,L/aLW,L/aLC,Figure 2-1: Homes Production Possibility Frontier,A One-Factor Economy,o,18,Relative Prices and Supply The particular amounts of each goods

17、 produced are determined by prices. The relative price of goods X (cheese) in terms of goods Y (wine) is the amount of goods Y (wine) that can be exchanged for one unit of goods X (cheese).（产品X对产品Y的相对价格是用多少单位的Y能换回一单位的X）,A One-Factor Economy,19,Relative Prices and Supply Examples of relative prices:

18、If a price of a can of Coke is $0.5, then the relative price of Coke is the amount of $ 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.,A One-Factor Economy,20,Denote with PC the dollar price of cheese and with PW the

19、 dollar price of wine. Denote with wW the dollar wage in the wine industry and with wC the dollar wage in the cheese industry. There are no profits in our one-factor model,the hourly wage rate in the cheese sector will equal the value of what a worker can produce in an hour, PC/aLC.（奶酪部门的单位工资率等于一个工人

20、在一个小时内生产的价值 ） The hourly wage rate in the wine sector will be PW/aLW.,A One-Factor Economy,21,The above relations 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.Or PC/aLCPW/aLW. In the absen

21、ce of trade, both goods are produced, and therefore PC / PW = aLC /aLW. （在没有国际贸易时，产品的相对价格等于它们的相对单位产品劳动投入。）,A One-Factor Economy,22,Trade in a One-Factor World,Assumptions of the model: There are two countries in the world (Home and Foreign). Each of the two countries produces two goods (say wine and

22、 cheese). Labor is the only factor of production. The supply of labor is fixed in each country. The productivity of labor in each goods is fixed. Labor is not mobile across the two countries. Perfect competition prevails in all markets. All variables with an asterisk refer to the Foreign country.,23

23、,Absolute Advantage（绝对优势） A country has an absolute advantage in a production of a goods if it has a lower unit labor requirement than the foreign country in this goods. Assume that aLC a*LC and aLW a*LW This assumption implies that Home has an absolute advantage in the production of both goods. Ano

24、ther way to see this is to notice that Home is more productive in the production of both goods than Foreign. Even 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（比较优势）.,Trade in a One-Facto

25、r World,24,Comparative Advantage Assume that aLC /aLW a*LC /a*LW(2-2) This assumption implies that the opportunity cost of cheese in terms of wine is lower in Home than it is in Foreign. In other words, in the absence of trade, the relative price of cheese at Home is lower than the relative price of

26、 cheese at Foreign. Home has a comparative advantage in cheese and will export it to Foreign in exchange for wine.,Trade in a One-Factor World,25,L*/a*LW,L*/a*LC,+1,Figure 2-2: Foreigns Production Possibility Frontier,Trade in a One-Factor World,26,Determining the Relative Price After Trade What det

27、ermines 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.（把世界作为一个整体来确定奶酪的相对供给和相对需求） The relative supply of cheese equals the total quantity of cheese supplied by both countries at each

28、 given relative price divided by the total quantity of wine supplied, (QC + Q*C )/(QW + Q*W). The relative demand of cheese in the world is a similar concept.,Trade in a One-Factor World,27,2,1,aLC/aLW,a*LC/a*LW,Figure 2-3: World Relative Supply and Demand,Trade in a One-Factor World,28,Trade in a O

29、ne-Factor World,First,the RS curve shows that there is no supply of cheese if the world price drops below aLC/aLW. -Assume aLC/aLWa*LC/a*LW, Home will specialize in the production of cheese. -Home will specialize in the production of wine whenever PC/PWaLC/aLW , or PC/aLCPW/aLW. -Similarly,Foreign w

30、ill specialize in wine production whenever PC/PWa*LC/a*LW. Second,when the relative price of cheese, PC/PW=aLC/aLW, Home workers are indifferent between producing cheese and wine. We have a flat section of the supply curve.,29,Trade in a One-Factor World,Third, for PC/PWa*LC/a*LW, both Home and Fore

31、ign will specialize in cheese production. There will be no wine production, so that the relative supply of cheese will become infinite. Fourth, At PC/PW=a*LC/a*LW, Foreign workers are indifferent between producing cheese and wine. We again have a flat section of the supply curve. Fifth, aLC/aLW PC/P

32、W a*LC/a*LW, the relative supply of cheese is (L/aLC)/(L*/a*LW).,30,The Gains from Trade If countries 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 w

33、ay of producing goods and services (that is, a new technology).,Trade in a One-Factor World,31,Another way to see the gains from trade 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 goo

34、ds a country can obtain for any given amount of the other commodity. In the absence of trade, the consumption possibility curve is the same as the production possibility curve. Trade enlarges the consumption possibility for each of the two countries.,Trade in a One-Factor World,32,Trade in a One-Fac

35、tor World,Figure 2-4: Trade Expands Consumption Possibilities,(a) Home,(b) Foreign,33,A Numerical Example,We must understand 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

36、 not be confused with absolute advantage; it is comparative, not absolute, advantage that determines who will and should produce a good.,34,A Numerical Example,aLC /aLW = 1/2 a*LC /a*LW = 2,35,A Numerical Example,The domestic country is more efficient in both industries, but it has a comparative adv

37、antage only in cheese production. The foreign country is less efficient in both industries, but it has a comparative advantage in wine production.,36,A Numerical Example,With trade, the equilibrium relative price of cheese must be between aLC /aLW = 1/2 and a*LC /a*LW = 2 Suppose that PC /PW = 1 in

38、equilibrium. In words, one kg of cheese trades for one liter of wine.,37,A Numerical Example,If the domestic country does not trade, it can use one hour of labor to produce 1/aLW = 1/2 liter of wine. If the domestic country does trade, it can use one hour of labor to produce 1/aLC = 1 kg of cheese,

39、sell this amount to the foreign country at current prices to obtain 1 liter of wine. If the foreign country does not trade, it can use one hour of labor to produce 1/a*LC = 1/6 kg of cheese. If the foreign country does trade, it can use one hour of labor to produce 1/a*LW = 1/3 liter of wine, sell t

40、his amount to the domestic country at current prices to obtain 1/3 kg of cheese.,38,Relative Wages（相对工资）,The relative wage of a countrys workers is the amount they are paid per hour, compared with the amount workers in another country are paid per hour. This wage rate lies between the ratios of the

41、two countries productivities in the two industries.（相对工资率位于两国的两个工业部门的相对劳动生产率之间）,39,Relative Wages,Suppose that PC = $12/kg and PW = $12/L Since domestic workers specialize in cheese production after trade, their hourly wages will be (1/aLC)PC = (1/1)$12 = $12 Since foreign workers specialize in wine

42、 production after trade, their hourly wages will be (1/a*LW)PW = (1/3)$12 = $4 The relative wage of domestic workers is therefore $12/$4 = 3,40,Relative Wages,So the relative wage lies between the ratio of the productivities in each industry. The domestic country is 6/1 = 6 times as productive in ch

43、eese production, but only 3/2 = 1.5 times as productive in wine production. The domestic country has a wage rate 3 times as high as that in the foreign country. These relationships imply that both countries have a cost advantage in production. The cost of high wages can be offset by high productivit

44、y. The cost of low productivity can be offset by low wages.,41,Relative Wages,Because foreign workers have a wage that is only 1/3 the wage of domestic workers, they are able to attain a cost advantage (in wine production), despite low productivity. Because domestic workers have a productivity that

45、is 6 times that of foreign workers (in cheese production), they are able to attain a cost advantage, despite high wages.,42,Relative Wages,In the Ricardian model, relative wages reflect relative productivities of the two countries. Is this an accurate assumption? Some argue that low wage countries p

46、ay low wages despite growing productivity, putting high wage countries at a cost disadvantage. But evidence shows that low wages are associated with low productivity.,43,Productivity and Wages,Source: International Labor Organization, World Bank, Bureau of Labor Statistics, and Orley Ashenfelter and

47、 Stepan Jurajda, “Cross-country Comparisons of Wage Rates,” working paper, Princeton University,44,Relative Wages,Other evidence shows that wages rise as productivity rises. In 2000, South Koreas labor productivity was 35% of the U.S. level and its average wages were about 38% of U.S. average wages.

48、 After the Korean War, South Korea was one of the poorest countries in the world, and its labor productivity was very low. Even by 1975, average wages in South Korea were still only 5% of U.S. average wages.,45,Disconceptions About Comparative Advantage,Productivity and Competitiveness The Pauper La

49、bor Argument（贫民劳动争论） Exploitation（剥削）,46,Comparative Advantage with Many Goods（多种产品）,Setting Up the Model Both countries consume and are able to produce a large number, N, of different goods. The technology of each country can be described by its unit labor requirement for each good.,47,Comparative

50、Advantage with Many Goods,Relative Wages and Specialization The pattern of trade will depend on the ratio of Home to Foreign wages. Goods will always be produced where it is cheapest to make them. For example, it will be cheaper to produce goods i in Home if waLi w/w*.,48,Comparative Advantage with

51、Many Goods,Table 2-4: Home and Foreign Unit Labor Requirements,49,Which country produces which goods? A country has a cost advantage in any good for which its relative productivity is higher than its relative wage.（对于一个国家来说，相对生产率高于相对工资率的产品具有成本优势） If, for example, w/w* = 3, Home will produce apples,

52、bananas, and caviar, while Foreign will produce only dates and enchiladas. Both countries will gain from this specialization.,Comparative Advantage with Many Goods,50,Determining the Relative Wage in the Multigood Model（相对工资的确定） To determine relative wages in a multigood economy we must look behind

53、the relative demand for goods (i.e., the relative derived demand).（要确定在多种产品经济中的相对工资，我们必须根据产品的相对需求来推知隐含的对劳动的相对需求 ） The relative demand for Home labor depends negatively on the ratio of Home to Foreign wages.,Comparative Advantage with Many Goods,51,Comparative Advantage with Many Goods,Figure 2-5: De

54、termination of Relative Wages,52,Transportation Costs and Non-traded Goods,The Ricardian model predicts that countries should completely specialize in production. But this rarely happens for primarily three reasons: 1. More than one factor of production reduces the tendency of specialization. 2. Pro

55、tectionism. 3. Transportation costs reduce or prevent trade, which may cause each country to produce the same good or service.,53,Transportation Costs and Non-traded Goods,Non-traded goods and services (ex., haircuts and auto repairs) exist due to high transportation costs. Countries tend to spend a large fraction of national income on non-traded goods and services. This fact has implications for th