劳动生产率和比较优势课件.ppt

1、1YOU ARE WELCOME!2International Economics国际经济学国际经济学主讲：余道先主讲：余道先3Chapter 2Labor Productivity and Comparative Advantage:The Ricardian Model劳动生产率和比较优势：李嘉图模型劳动生产率和比较优势：李嘉图模型4PreviewlIntroductionlThe Concept of Comparative Advantage（比较优势比较优势）lA One-Factor Economy（单一要素经济单一要素经济）lTrade in a One-Factor World

2、（单一要素世界的贸易单一要素世界的贸易）lComparative Advantage with Many Goods（多种产品多种产品的比较优势的比较优势）lAdding Transport Costs and Nontraded Goods（引入引入运输成本和非贸易品运输成本和非贸易品）lEmpirical Evidence on the Ricardian ModellSummary5lCountries engage in international trade for two basic reasons:lThey are different from each other in te

3、rms of climate,land,capital,labor,and technology.lThey try to achieve scale economies（规模经规模经济济）in production.lThe Ricardian model is based on technological differences across countries.lThese technological differences are reflected in differences in the productivity of labor.Introduction6lThe Ricard

4、ian model uses the concepts of opportunity cost and comparative advantage.The Concept of Comparative Advantage7lFor example，On Valentines Day the U.S.demand for roses is about 10 million roses.lGrowing roses in the U.S.in the winter is difficult.lHeated greenhouses should be used.lThe costs for ener

5、gy,capital,and labor are substantial.lResources for the production of roses could be used to produce other goods,say computers.The Concept of Comparative Advantage8lOpportunity Cost（机会成本机会成本）lThe opportunity cost of roses in terms of computers is the number of computers that could be produced with t

6、he same resources as a given number of roses.lComparative Advantage（比较优势比较优势）lA 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

7、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 Concept of Comparative Advantage9lSuppose that in the U.S.10 million roses can be produced with the same resources as 100,000 computers.lSuppose also that in South America 10 million roses can be produced with the same resources as 30,000 computers.lThis examp

8、le assumes that South American workers are less productive than U.S.workers.The Concept of Comparative Advantage10lIf each country specializes in the production of the goods with lower opportunity costs,trade can be beneficial for both countries.lRoses have lower opportunity costs in South America.l

9、Computers have lower opportunity costs in the U.S.lThe benefits from trade can be seen by considering the changes in production of roses and computers in both countries.The Concept of Comparative Advantage11Table 2-1:Hypothetical Changes in ProductionThe Concept of Comparative Advantage12lThe exampl

10、e in Table 2-1 illustrates the principle of comparative advantage:lIf 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会从贸易

11、中受益）lWhat determines comparative advantage?lAnswering this question would help us understand how country differences determine the pattern of trade(which goods a country exports).The Concept of Comparative Advantage13A One-Factor Economy （单一要素经济）（单一要素经济）lAssume that we are dealing with an economy(wh

12、ich we call Home).In this economy:lLabor is the only factor of production.lOnly two goods(say wine and cheese)are produced.lThe supply of labor is fixed in each country.lThe productivity of labor in each goods is fixed.lPerfect competition prevails in all markets.14lThe technology of Homes economy c

13、an be summarized by labor productivity in each industry,expressed in terms of unit labor requirements:lThe unit labor requirement is the number of hours of labor required to produce one unit of output.lDenote with aLW the unit labor requirement for wine(e.g.if aLW=2,then one needs 2 hours of labor t

14、o produce one gallon of wine).lDenote with aLC the unit labor requirement for cheese(e.g.if aLC=1,then one needs 1 hour of labor to produce a pound of cheese).A One-Factor Economy15lThe economys total resources are defined as L,the total labor supply.e.g.if L=120,then this economy is endowed with 12

15、0 hours of labor or 120 workers.A One-Factor Economy16lProduction PossibilitieslThe production possibility frontier(PPF)（生产可能性生产可能性边界边界）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 differ

16、ent mixes of goods the economy can produce.lThe PPF of our economy is given by the following equation:aLCQC+aLWQW=L (2-1)lFrom our previous example,we get:QC+2QW=120A One-Factor Economy17L/aLWL/aLCFigure 2-1:Homes Production Possibility FrontierA One-Factor EconomyAbsolute value of slope equalsoppor

17、tunity cost of cheese interms of wineFPHome wine production,QW,in gallonsHome cheese production,QC,in poundso18lRelative Prices and SupplylThe particular amounts of each goods produced are determined by prices.lThe relative price of goods X(cheese)in terms of goods Y(wine)is the amount of goods Y(wi

18、ne)that can be exchanged for one unit of goods X(cheese).（产品产品X对产品对产品Y的相对价格是用多少的相对价格是用多少单位的单位的Y能换回一单位的能换回一单位的X）A One-Factor Economy19lRelative Prices and SupplylExamples of relative prices:lIf 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

19、one unit of Coke,which is 0.5.lThe relative price of a$in terms of Coke is 2 cans of Coke per dollar.A One-Factor Economy20lDenote 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 cheese ind

20、ustry.lThere 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在一个小（奶酪部门的单位工资率等于一个工人在一个小时内生产的价值时内生产的价值）The hourly wage rate in the wine sector will be PW/aLW.A One-Factor Economy21lThe

21、 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.lIn the absence 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-Fa

22、ctor Economy22Trade in a One-Factor WorldlAssumptions of the model:lThere are two countries in the world(Home and Foreign).lEach of the two countries produces two goods(say wine and cheese).lLabor is the only factor of production.lThe supply of labor is fixed in each country.lThe productivity of lab

23、or in each goods is fixed.lLabor is not mobile across the two countries.lPerfect competition prevails in all markets.lAll variables with an asterisk refer to the Foreign country.23lAbsolute Advantage（绝对优势）（绝对优势）lA country has an absolute advantage in a production of a goods if it has a lower unit la

24、bor requirement than the foreign country in this goods.lAssume that aLC a*LC and aLW a*LWlThis 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.lEven i

25、f Home has an absolute advantage in both goods,beneficial trade is possible.lThe pattern of trade will be determined by the concept of comparative advantage（比较优势）（比较优势）.Trade in a One-Factor World24lComparative AdvantagelAssume that aLC/aLW a*LC/a*LW(2-2)lThis assumption implies that the opportunity

26、 cost of cheese in terms of wine is lower in Home than it is in Foreign.lIn other words,in the absence of trade,the relative price of cheese at Home is lower than the relative price of cheese at Foreign.lHome has a comparative advantage in cheese and will export it to Foreign in exchange for wine.Tr

27、ade in a One-Factor World25F*P*L*/a*LWL*/a*LCForeign wine production,Q*W,in gallonsForeign cheese production,Q*C,in pounds+1Figure 2-2:Foreigns Production Possibility FrontierTrade in a One-Factor World26lDetermining the Relative Price After TradelWhat determines the relative price(e.g.,PC/PW)after

28、trade?lTo 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（把世界作为一个整体来确定奶酪的相对供给和相对需求）和相对需求）lThe relative supply of cheese equals the total quantity of cheese supplied by both countries at each given relative price d

29、ivided by the total quantity of wine supplied,(QC+Q*C)/(QW+Q*W).lThe relative demand of cheese in the world is a similar concept.Trade in a One-Factor World272RDRD1QaLC/aLWa*LC/a*LWRSFigure 2-3:World Relative Supply and DemandTrade in a One-Factor WorldRelative priceof cheese,PC/PWRelative quantityo

30、f cheese,QC+Q*C QW+Q*WL/aLCL*/a*LW28Trade in a One-Factor WorldlFirst,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/PWaL

31、C/aLW,or PC/aLCPW/aLW.-Similarly,Foreign will specialize in wine production whenever PC/PWa*LC/a*LW,both Home and Foreign will specialize in cheese production.There will be no wine production,so that the relative supply of cheese will become infinite.lFourth,At PC/PW=a*LC/a*LW,Foreign workers are in

32、different between producing cheese and wine.We again have a flat section of the supply curve.lFifth,aLC/aLW PC/PW a*LC/a*LW,the relative supply of cheese is(L/aLC)/(L*/a*LW).30lThe Gains from TradelIf countries specialize according to their comparative advantage,they all gain from this specializatio

33、n and trade.lWe will demonstrate these gains from trade in two ways.lFirst,we can think of trade as a new way of producing goods and services(that is,a new technology).Trade in a One-Factor World31lAnother way to see the gains from trade is to consider how trade affects the consumption in each of th

34、e two countries.lThe consumption possibility frontier states the maximum amount of consumption of a goods a country can obtain for any given amount of the other commodity.lIn the absence of trade,the consumption possibility curve is the same as the production possibility curve.lTrade enlarges the co

35、nsumption possibility for each of the two countries.Trade in a One-Factor World32Trade in a One-Factor WorldFigure 2-4:Trade Expands Consumption PossibilitiesTFPT*P*F*(a)Home(b)ForeignQuantityof wine,QWQuantityof cheese,QCQuantityof wine,Q*WQuantityof cheese,Q*C33A Numerical ExamplelWe must understa

36、nd 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

37、 a good.34A Numerical ExamplelaLC/aLW=1/2 a*LC/a*LW=2Unit labor requirements for domestic and foreign countriesCheeseWineDomesticaLC=1 hour/kgaLW=2 hours/LForeigna*LC=6 hours/kga*LC=3 hours/L35A Numerical ExamplelThe domestic country is more efficient in both industries,but it has a comparative adva

38、ntage only in cheese production.lThe foreign country is less efficient in both industries,but it has a comparative advantage in wine production.36A Numerical ExamplelWith trade,the equilibrium relative price of cheese must be between aLC/aLW=1/2 and a*LC/a*LW=2lSuppose that PC/PW=1 in equilibrium.lI

39、n words,one kg of cheese trades for one liter of wine.37A Numerical ExamplelIf the domestic country does not trade,it can use one hour of labor to produce 1/aLW=1/2 liter of wine.lIf the domestic country does trade,it can use one hour of labor to produce 1/aLC=1 kg of cheese,sell this amount to the

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

41、try at current prices to obtain 1/3 kg of cheese.38Relative Wages（相对工资）（相对工资）lThe 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.lThis wage rate lies between the ratios of the two countries productivities

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

43、 after trade,their hourly wages will be(1/a*LW)PW=(1/3)$12=$4 lThe relative wage of domestic workers is therefore$12/$4=340Relative WageslSo the relative wage lies between the ratio of the productivities in each industry.lThe domestic country is 6/1=6 times as productive in cheese production,but onl

44、y 3/2=1.5 times as productive in wine production.lThe domestic country has a wage rate 3 times as high as that in the foreign country.lThese relationships imply that both countries have a cost advantage in production.lThe cost of high wages can be offset by high productivity.lThe cost of low product

45、ivity can be offset by low wages.41Relative WageslBecause 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.lBecause domestic workers have a productivity that is 6 times that of foreign work

46、ers(in cheese production),they are able to attain a cost advantage,despite high wages.42Relative WageslIn the Ricardian model,relative wages reflect relative productivities of the two countries.lIs this an accurate assumption?lSome argue that low wage countries pay low wages despite growing producti

47、vity,putting high wage countries at a cost disadvantage.lBut evidence shows that low wages are associated with low productivity.43Productivity and WagesSource:International Labor Organization,World Bank,Bureau of Labor Statistics,and Orley Ashenfelter and Stepan Jurajda,“Cross-country Comparisons of

48、 Wage Rates,”working paper,Princeton University44Relative WageslOther evidence shows that wages rise as productivity rises.lIn 2000,South Koreas labor productivity was 35%of the U.S.level and its average wages were about 38%of U.S.average wages.lAfter the Korean War,South Korea was one of the poores

49、t 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.45Disconceptions About Comparative AdvantagelProductivity and CompetitivenesslThe Pauper Labor Argument（贫民劳动争论）（贫民劳动争论）lExploitation（剥削）（剥削）46Comparative

50、Advantage with Many Goods（多种产品）（多种产品）lSetting Up the ModellBoth countries consume and are able to produce a large number,N,of different goods.lThe technology of each country can be described by its unit labor requirement for each good.312*123.LLNLLLLLLNaaaaaaaa47Comparative Advantage with Many Goods