劳动生产率和比较优势：李嘉图模型

1YOUAREWELCOME!2InternationalEconomics国际经济学主讲：余道先[e-mail]3Chapter3LaborProductivityandComparativeAdvantage:TheRicardianModel劳动生产率和比较优势：李嘉图模型4PreviewIntroductionTheConceptofComparativeAdvantage（比较优势）AOne-FactorEconomy（单一要素经济）TradeinaOne-FactorWorld（单一要素世界的贸易）ComparativeAdvantagewithManyGoods（多种产品的比较优势）AddingTransportCostsandNontradedGoods（引入运输成本和非贸易品）EmpiricalEvidenceontheRicardianModelSummary5Countriesengageininternationaltradefortwobasicreasons:Theyaredifferentfromeachotherintermsofclimate,land,capital,labor,andtechnology.Theytrytoachievescaleeconomies（规模经济）inproduction.TheRicardianmodelisbasedontechnologicaldifferencesacrosscountries.Thesetechnologicaldifferencesarereflectedindifferencesintheproductivityoflabor.Introduction6TheRicardianmodelusestheconceptsofopportunitycostandcomparativeadvantage.TheConceptofComparativeAdvantage7Forexample，OnValentine’sDaytheU.S.demandforrosesisabout10millionroses.GrowingrosesintheU.S.inthewinterisdifficult.Heatedgreenhousesshouldbeused.Thecostsforenergy,capital,andlaboraresubstantial.Resourcesfortheproductionofrosescouldbeusedtoproduceothergoods,saycomputers.TheConceptofComparativeAdvantage8OpportunityCost（机会成本）Theopportunitycostofrosesintermsofcomputersisthenumberofcomputersthatcouldbeproducedwiththesameresourcesasagivennumberofroses.ComparativeAdvantage（比较优势）Acountryhasacomparativeadvantageinproducingagoodsiftheopportunitycostofproducingthatgoodsintermsofothergoodsislowerinthatcountrythanitisinothercountries.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。TheConceptofComparativeAdvantage9SupposethatintheU.S.10millionrosescanbeproducedwiththesameresourcesas100,000computers.SupposealsothatinSouthAmerica10millionrosescanbeproducedwiththesameresourcesas30,000computers.ThisexampleassumesthatSouthAmericanworkersarelessproductivethanU.S.workers.TheConceptofComparativeAdvantage10Ifeachcountryspecializesintheproductionofthegoodswithloweropportunitycosts,tradecanbebeneficialforbothcountries.RoseshaveloweropportunitycostsinSouthAmerica.ComputershaveloweropportunitycostsintheU.S.Thebenefitsfromtradecanbeseenbyconsideringthechangesinproductionofrosesandcomputersinbothcountries.TheConceptofComparativeAdvantage11Table3-1:HypotheticalChangesinProductionTheConceptofComparativeAdvantage12TheexampleinTable3-1illustratestheprincipleofcomparativeadvantage:Ifeachcountryexportsthegoodsinwhichithascomparativeadvantage(loweropportunitycosts),thenallcountriescaninprinciplegainfromtrade.（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）Whatdeterminescomparativeadvantage?Answeringthisquestionwouldhelpusunderstandhowcountrydifferencesdeterminethepatternoftrade(whichgoodsacountryexports).TheConceptofComparativeAdvantage13AOne-FactorEconomy（单一要素经济）Assumethatwearedealingwithaneconomy(whichwecallHome).Inthiseconomy:Laboristheonlyfactorofproduction.Onlytwogoods(saywineandcheese)areproduced.Thesupplyoflaborisfixedineachcountry.Theproductivityoflaborineachgoodsisfixed.Perfectcompetitionprevailsinallmarkets.14ThetechnologyofHome’seconomycanbesummarizedbylaborproductivityineachindustry,expressedintermsofunitlaborrequirements:Theunitlaborrequirementisthenumberofhoursoflaborrequiredtoproduceoneunitofoutput.DenotewithaLWtheunitlaborrequirementforwine(e.g.ifaLW=2,thenoneneeds2hoursoflabortoproduceonegallonofwine).DenotewithaLCtheunitlaborrequirementforcheese(e.g.ifaLC=1,thenoneneeds1houroflabortoproduceapoundofcheese).AOne-FactorEconomy15Theeconomy’stotalresourcesaredefinedasL,thetotallaborsupply.e.g.ifL=120,thenthiseconomyisendowedwith120hoursoflaboror120workers.AOne-FactorEconomy16ProductionPossibilitiesTheproductionpossibilityfrontier(PPF)（生产可能性边界）ofaneconomyshowsthemaximumamountofagoods(saywine)thatcanbeproducedforanygivenamountofanother(saycheese),andviceversa.Orillustratesthedifferentmixesofgoodstheeconomycanproduce.ThePPFofoureconomyisgivenbythefollowingequation:aLCQC+aLWQW=L(3-1)Fromourpreviousexample,weget:QC+2QW=120AOne-FactorEconomy17L/aLWL/aLCFigure2-1:Home’sProductionPossibilityFrontierAOne-FactorEconomyAbsolutevalueofslopeequalsopportunitycostofcheeseintermsofwineFPHomewineproduction,QW,ingallonsHomecheeseproduction,QC,inpoundso18RelativePricesandSupplyTheparticularamountsofeachgoodsproducedaredeterminedbyprices.TherelativepriceofgoodsX(cheese)intermsofgoodsY(wine)istheamountofgoodsY(wine)thatcanbeexchangedforoneunitofgoodsX(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）AOne-FactorEconomy19RelativePricesandSupplyExamplesofrelativeprices:IfapriceofacanofCokeis$0.5,thentherelativepriceofCokeistheamountof$thatcanbeexchangedforoneunitofCoke,whichis0.5.Therelativepriceofa$intermsofCokeis2cansofCokeperdollar.AOne-FactorEconomy20DenotewithPCthedollarpriceofcheeseandwithPWthedollarpriceofwine.DenotewithwWthedollarwageinthewineindustryandwithwCthedollarwageinthecheeseindustry.Therearenoprofitsinourone-factormodel,thehourlywagerateinthecheesesectorwillequalthevalueofwhataworkercanproduceinanhour,PC/aLC.（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