第二章劳动生产率和比较优势李嘉图模型

1第二章劳动生产率和比较优势：李嘉图模型•导论•比较优势的概念•单一要素经济•单一要素经济中的贸易•对比较优势的误解•多商品中的比较优势•运输费用和非贸易品•对李嘉图模型的实证研究•总结2•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scaleeconomies(规模经济)•李嘉图模型（TheRicardianmodel）基于各国间技术差异–技术差异反映在劳动生产率上（productivityoflabor）.导论3•美国情人节的例子。OnValentine’sDaytheU.S.demandforrosesisabout10million（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4•OpportunityCost（机会成本）–Theopportunitycostofroses（A)intermsofcomputers（B)isthenumberofcomputers（B)thatcouldbeproducedwiththesameresourcesasagivennumberofroses（A).–以商品B衡量生产商品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。•ComparativeAdvantage（比较优势）–Acountryhasacomparativeadvantageinproducingagoodiftheopportunitycostofproducingthatgoodintermsofothergoodsislowerinthatcountrythanitisinothercountries.–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。5•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。6•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。7Table2-1:产量的变化8玫瑰的机会成本计算机的机会成本UnitedStates0.01100SouthAmerica0.0033339•TheexampleinTable2-1illustratestheprincipleofcomparativeadvantage:–Ifeachcountryexportsthegoodsinwhichithascomparativeadvantage(loweropportunitycosts),thenallcountriescaninprinciplegainfromtrade.•Whatdeterminescomparativeadvantage?–Answeringthisquestionwouldhelpusunderstandhowcountrydifferencesdeterminethepatternoftrade(whichgoodsacountryexports).（RicardianModel）102-2AOne-FactorEconomy•Assumethatwearedealingwithaneconomy(whichwecallHome).Inthiseconomy（五个假定条件）–Laboristheonlyfactorofproduction.（一种要素:劳动力）–Onlytwogoods(saywineandcheese)areproduced.（两种商品）–Thesupplyoflaborisfixedineachcountry.（劳动要素供应不变）–Theproductivityoflaborineachgoodisfixed.（劳动生产率不变）–Perfectcompetitionprevailsinallmarkets.（完全竞争）11•Theconstantlaborproductivityismodeledwiththespecificationofunitlaborrequirements:–Theunitlaborrequirement（单位产品劳动投入）isthenumberofhoursoflaborrequiredtoproduceoneunitofoutput.（单位：人小时，person-hours）•DenotewithaLWtheunitlaborrequirementforwine(e.g.ifaLW=2,thenoneneeds2hoursoflabortoproduceonegallonofwine).•DenotewithaLCtheunitlaborrequirementforcheese(e.g.ifaLC=1,thenoneneeds1houroflabortoproduceapoundofcheese).•总资源为劳动力（L）Theeconomy’stotalresourcesaredefinedasL,thetotallaborsupply(e.g.ifL=120,thenthiseconomyisendowedwith120hoursoflaboror120workers).12•ProductionPossibilities(生产能力)–Theproductionpossibilityfrontier(PPF，生产可能性边界)ofaneconomyshowsthemaximumamountofagood(saywine)thatcanbeproducedforanygivenamountofanother(saycheese),andviceversa.（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）–ThePPFofoureconomyisgivenbythefollowingequation:aLC×QC+aLW×QW≤L(2-1)–Fromourpreviousexample,weget:QC+2QW≤12013L/aLWL/aLCFigure2-1:Home’sProductionPossibilityFrontierAbsolutevalueofslopeequalsopportunitycostofcheeseintermsofwineFPHomewineproduction,QW,ingallonsHomecheeseproduction,QC,inpounds14•RelativePricesandSupply–Theparticularamountsofeachgoodproducedaredeterminedbyprices.–Therelativeprice(相对价格)ofgoodX(cheese)intermsofgoodY(wine)istheamountofgoodY(wine)thatcanbeexchangedforoneunitofgoodX(cheese).–Examplesofrelativeprices:•IfapriceofacanofCokeis$0.5,thentherelativepriceofCokeistheamountof$thatcanbeexchangedforoneunitofCoke,whichis0.5.•Therelativepriceofa$intermsofCokeis2cansofCokeperdollar.15•DenotewithPCthedollarpriceofcheeseandwithPWthedollarpriceofwine.DenotewithwWthedollarwageinthewineindustryandwithwCthedollarwageinthecheeseindustry.(工资率)：葡萄酒部门工资率为PW/aW•Thenunderperfectcompetition,thenon-negativeprofitconditionimplies:–IfPW/a–IfPW/aW=wW,thenthereisproductionofQW.–IfPC/aCwC,thenthereisnoproductionofQC.–IfPC/aC=wC,thenthereisproductionofQC.16•Theaboverelationsimplythatiftherelativepriceofcheese(PC/PW)exceedsitsopportunitycost(aLC/aLW),thentheeconomywillspecializeintheproductionofcheese.（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）•Intheabsenceoftrade,bothgoodsareproduced,andthereforePC/PW=aLC/aLW.172-3TradeinaOne-FactorWorld•Assumptionsofthemodel（模型假设）:–1.Therearetwocountriesintheworld(HomeandForeign).–2.Eachofthetwocountriesproducestwogoods(saywineandcheese).–3.Laboristheonlyfactorofproduction(生产要素).–4.Thesupplyoflaborisfixedineachcountry.–5.Theproductivityoflaborineachgoodisfixed.–6.Laborisnotmobileacrossthetwocountries.–7.Perfectcompetitionprevailsinallmarkets.–8.Allvariableswithanasteriskre’fertotheForeigncountry.18•AbsoluteAdvantage(绝对优势)–Acountryhasanabsoluteadvantageinaproductionofagoodifithasalowerunitlaborrequirementthantheforeigncountryinthisgood.–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。–AssumethataLCa*LCandaLWa*LW•ThisassumptionimpliesthatHomehasanabsoluteadvantageintheproductionofbothgoods.AnotherwaytoseethisistonoticethatHomeismoreproductiveintheproductionofbothgoodsthanForeign.•EvenifHomehasanabsoluteadvantageinbothgoods,beneficialtradeispossible.•Thepatternoftradewillbedeterminedbytheconceptofcomparativeadvantage.19•ComparativeAdvantage–假设本国用酒衡量的奶酪的机会成本小于外国