andInternationalTrade发展经济学教程-厦门大学

andInternationalTrade发展经济学教程-厦门大学IntroductionEconomiesofScaleandInternationalTrade:AnOverviewEconomiesofScaleandMarketStructureTheTheoryofImperfectCompetitionMonopolisticCompetitionandTradeDumpingTheTheoryofExternalEconomiesExternalEconomiesandInternationalTradeSummaryChapterOrganization2IntroductionCountriesengageininternationaltradefortwobasicreasons:Countriestradebecausetheydiffereitherintheirresourcesorintechnology.Countriestradeinordertoachievescaleeconomiesorincreasingreturnsinproduction.Twomodelsofinternationaltradeinwhicheconomiesofscaleandimperfectcompetitionplayacrucialrole:MonopolisticcompetitionmodelDumpingmodel3EconomiesofScaleandInternationalTrade:AnOverviewModelsoftradebasedoncomparativeadvantage(e.g.Ricardianmodel)usedtheassumptionsofconstantreturnstoscaleandperfectcompetition:Increasingtheamountofallinputsusedintheproductionofanycommoditywillincreaseoutputofthatcommodityinthesameproportion.Inpractice,manyindustriesarecharacterizedbyeconomiesofscale(alsoreferredtoasincreasingreturns).Productionismostefficient,thelargerthescaleatwhichittakesplace.4Underincreasingreturnstoscale:Outputgrowsproportionatelymorethantheincreaseinallinputs.Averagecosts(costsperunit)declinewiththesizeofthemarket.EconomiesofScaleandInternationalTrade:AnOverview5EconomiesofScaleandInternationalTrade:AnOverviewTable6-1:RelationshipofInputtoOutputforaHypotheticalIndustry6EconomiesofScaleand

MarketStructureEconomiesofscalecanbeeither:ExternalThecostperunitdependsonthesizeoftheindustrybutnotnecessarilyonthesizeofanyonefirm.Anindustrywilltypicallyconsistofmanysmallfirmsandbeperfectlycompetitive.InternalThecostperunitdependsonthesizeofanindividualfirmbutnotnecessarilyonthatoftheindustry.Themarketstructurewillbeimperfectlycompetitivewithlargefirmshavingacostadvantageoversmall.Bothtypesofscaleeconomiesareimportantcausesofinternationaltrade.7ImperfectcompetitionFirmsareawarethattheycaninfluencethepriceoftheirproduct.Theyknowthattheycansellmoreonlybyreducingtheirprice.Eachfirmviewsitselfasapricesetter,choosingthepriceofitsproduct,ratherthanapricetaker.Thesimplestimperfectlycompetitivemarketstructureisthatofapuremonopoly,amarketinwhichafirmfacesnocompetition.TheTheoryof

ImperfectCompetition8Monopoly:ABriefReviewMarginalrevenue

TheextrarevenuethefirmgainsfromsellinganadditionalunitItscurve,MR,alwaysliesbelowthedemandcurve,D.Inordertosellanadditionalunitofoutputthefirmmustlowerthepriceofallunitssold(notjustthemarginalone).TheTheoryof

ImperfectCompetition9TheTheoryof

ImperfectCompetitionFigure6-1:MonopolisticPricingandProductionDecisionsDCost,CandPrice,PQuantity,QMonopolyprofitsACPMQMMRMCAC10MarginalRevenueandPriceMarginalrevenueisalwayslessthantheprice.Therelationshipbetweenmarginalrevenueandpricedependsontwothings:HowmuchoutputthefirmisalreadysellingTheslopeofthedemandcurveIttellsushowmuchthemonopolisthastocuthispricetosellonemoreunitofoutput.TheTheoryof

ImperfectCompetition11Assumethatthedemandcurvethefirmfacesisastraightline:

Q=A–B

x

P (6-1)ThentheMRthatthefirmfacesisgivenby:

MR=P–Q/B (6-2)AverageandMarginalCostsAverageCost(AC)is

totalcostdividedbyoutput.MarginalCost(MC)is

theamountitcoststhefirmtoproduceoneextraunit.TheTheoryof

ImperfectCompetition12Whenaveragecostsdeclineinoutput,marginalcostisalwayslessthanaveragecost.Supposethecostsofafirm,C,taketheform:

C=F+c

x

Q (6-3)Thisisalinearcostfunction.Thefixedcostinalinearcostfunctiongivesrisetoeconomiesofscale,becausethelargerthefirm’soutput,thelessisfixedcostperunit.Thefirm’saveragecostsisgivenby:

AC=C/Q=F/Q+c(6-4)TheTheoryof

ImperfectCompetition13Figure6-2:AverageVersusMarginalCostTheTheoryof

ImperfectCompetitionAveragecostMarginalcost120345624681012141618202224CostperunitOutput14MonopolisticCompetitionOligopoly

Internaleconomiesgenerateanoligopolymarketstructure.Thereareseveralfirms,eachofwhichislargeenoughtoaffectprices,butnonewithanuncontestedmonopoly.Strategicinteractionsamongoligopolistshavebecomeimportant.Eachfirmdecidesitsownactions,takingintoaccounthowthatdecisionmightinfluenceitsrival’sactions.TheTheoryof

ImperfectCompetition15MonopolisticcompetitionAspecialcaseofoligopolyTwokeyassumptionsaremadetogetaroundtheproblemofinterdependence:Eachfirmisassumedtobeabletodifferentiateitsproductfromitsrivals.Eachfirmisassumedtotakethepriceschargedbyitsrivalsasgiven.TheTheoryof

ImperfectCompetition16Arethereanymonopolisticallycompetitiveindustriesintherealworld?Someindustriesmaybereasonableapproximations(e.g.,theautomobileindustryinEurope)Themainappealofthemonopolisticcompetitionmodelisnotitsrealism,butitssimplicity.TheTheoryof

ImperfectCompetition17AssumptionsoftheModelImagineanindustryconsistingofanumberoffirmsproducingdifferentiatedproducts.Weexpectafirm:Tosellmorethelargerthetotaldemandforitsindustry’sproductandthehigherthepriceschargedbyitsrivalsToselllessthegreaterthenumberoffirmsintheindustryandthehigheritsownpriceTheTheoryof

ImperfectCompetition18

where:Qisthefirm’ssalesSisthetotalsalesoftheindustrynisthenumberoffirmsintheindustrybisaconstanttermrepresentingtheresponsivenessofafirm’ssalestoitspricePisthepricechargedbythefirmitselfAparticularequationforthedemandfacingafirmthathasthesepropertiesis:

Q=S

x[1/n–b

x(P–P)](6-5)TheTheoryof

ImperfectCompetitionPistheaveragepricechargedbyitscompetitors19MarketEquilibriumAllfirmsinthisindustryaresymmetricThedemandfunctionandcostfunctionareidenticalforallfirms.Themethodfordeterminingthenumberoffirmsandtheaveragepricechargedinvolvesthreesteps:Wederivearelationshipbetweenthenumberoffirmsandtheaveragecostofatypicalfirm.Wederivearelationshipbetweenthenumberoffirmsandthepriceeachfirmcharges.Wederivetheequilibriumnumberoffirmsandtheaveragepricethatfirmscharge.TheTheoryof

ImperfectCompetition20ThenumberoffirmsandaveragecostHowdotheaveragecostsdependonthenumberoffirmsintheindustry?TheTheoryof

ImperfectCompetitionUndersymmetry,P=P,equation(6-5)tellsusthat

Q=S/nbutequation(6-4)showsusthattheaveragecostdependsinverselyonafirm’soutput.Weconcludethataveragecostdependsonthesizeofthemarketandthenumberoffirmsintheindustry: AC=F/Q+c=n

x

F/S+c(6-6)Themorefirmsthereareintheindustrythehigheristheaveragecost.21PPCostC,andPrice,PNumberoffirms,nCCP3AC3n3n1AC1n2AC2EFigure6-3:EquilibriuminaMonopolisticallyCompetitiveMarketTheTheoryof

ImperfectCompetitionP2,P122ThenumberoffirmsandthepriceThepricethetypicalfirmchargesdependsonthenumberoffirmsintheindustry.Themorefirms,themorecompetition,andhencethelowertheprice.Inthemonopolisticcompetitionmodelfirmsareassumedtotakeeachothers’pricesasgiven.TheTheoryof

ImperfectCompetitionIfeachfirmtreatsPasgiven,wecanrewritethedemandcurve(6-5)intheform: Q=(S/n+S

x

b

x

P)–S

x

b

x

P(6-7)23Profit-maximizingfirmssetmarginalrevenueequaltotheirmarginalcost,c.ThisgeneratesanegativerelationshipbetweenthepriceandthenumberoffirmsinthemarketwhichisthePPcurve: P=c+1/(b

x

n) (6-10)Themorefirmsthereareintheindustry,thelowerthepriceeachfirmwillcharge.TheTheoryof

ImperfectCompetition24TheequilibriumnumberoffirmsThedownward-slopingcurvePPshowsthatthemorefirms,thelowerthepriceeachfirmwillcharge.Themorefirms,themorecompetitioneachfirmfaces.Theupward-slopingcurveCCtellsusthatthemorefirmsthereare,thehighertheaveragecostofeachfirm.Ifthenumberoffirmsincreases,eachfirmwillsellless,sofirmswillnotbeabletomoveasfardowntheiraveragecostcurve.TheTheoryof

ImperfectCompetition25LimitationsoftheMonopolisticCompetitionModelTwokindsofbehaviorariseinthegeneraloligopolysettingthatareexcludedbyassumptionfromthemonopolisticcompetitionmodel:Collusivebehavior:CanraisetheprofitsofallfirmsattheexpenseofconsumersMaybemanagedthroughexplicitagreementsorthroughtacitcoordinationstrategiesStrategicbehavior:IsadoptedbyfirmstoaffectthebehaviorofcompetitorsinadesirablewayDeterspotentialrivalsfromenteringanindustryTheTheoryof

ImperfectCompetition26Themonopolisticcompetitionmodelcanbeusedtoshowhowtradeleadsto:IncreasedmarketsizeMutualgainsfromaintegratedmarketEconomicsofscaleintra-industrytradeMonopolisticCompetitionandTrade27Figure6-4:EffectsofaLargerMarketCostC,andPrice,PNumberoffirms,nCC1n1

P11PPn2P22CC2MonopolisticCompetitionandTrade28MonopolisticCompetitionandTradeCC: AC=F/Q+c=n

x

F/S+c

PP:

P=c+1/(b

x

n)

29GainsfromanIntegratedMarket:ANumericalExleExle:Supposethatautomobilesareproducedbyamonopolisticallycompetitiveindustry.Assumethefollowing:b=1/30,000,F=$750,000,000,c=$5000Therearetwocountries(HomeandForeign)thathavethesamecostsofautomobileproduction.Annualsalesofautomobilesare900,000atHomeand1.6millionatForeign.MonopolisticCompetitionandTrade30Figure6-5:EquilibriumintheAutomobileMarketMonopolisticCompetitionandTrade31Figure6-5:ContinuedMonopolisticCompetitionandTrade32Figure6-5:ContinuedMonopolisticCompetitionandTrade33Table6-2:HypotheticalExleofGainsfromMarketIntegrationMonopolisticCompetitionandTrade34EconomiesofScaleandComparativeAdvantageAssumptions:Therearetwocountries:Home(thecapital-abundantcountry)andForeign.Therearetwoindustries:manufactures(thecapital-intensiveindustry)andfood.Neithercountryisabletoproducethefullrangeofmanufacturedproductsbyitselfduetoeconomiesofscale.MonopolisticCompetitionandTrade35Figure6-6:TradeinaWorldWithoutIncreasingReturnsHome(capitalabundant)Foreign(laborabundant)ManufacturesFoodMonopolisticCompetitionandTrade36Ifmanufacturesisamonopolisticallycompetitivesector,worldtradeconsistsoftwoparts:IntraindustrytradeTheexchangeofmanufacturesformanufacturesInterindustrytradeTheexchangeofmanufacturesforfoodMonopolisticCompetitionandTrade37Figure6-7:TradewithIncreasingReturnsandMonopolisticCompetitionHome(capitalabundant)Foreign(laborabundant)ManufacturesFoodInterindustrytradeIntraindustrytradeMonopolisticCompetitionandTrade38Maindifferencesbetweeninterindustryandintraindustrytrade:Interindustrytradereflectscomparativeadvantage,whereasintraindustrytradedoesnot.Thepatternofintraindustrytradeitselfisunpredictable,whereasthatofinterindustrytradeisdeterminedbyunderlyingdifferencesbetweencountries.Therelativeimportanceofintraindustryandinterindustrytradedependsonhowsimilarcountriesare.MonopolisticCompetitionandTrade39TheSignificanceofIntraindustryTradeAboutone-fourthofworldtradeconsistsofintra-industrytrade.Intra-industrytradeplaysaparticularlylargeroleinthetradeinmanufacturedgoodsamongadvancedindustrialnations,whichaccountsformostofworldtrade.MonopolisticCompetitionandTrade40Table6-3:IndexesofIntraindustryTradeforU.S.Industries,1993MonopolisticCompetitionandTrade41TheEconomicsofDumpingPricediscriminationThepracticeofchargingdifferentcustomersdifferentpricesDumpingThemostcommonformofpricediscriminationininternationaltradeApricingpracticeinwhichafirmchargesalowerpriceforanexportedgoodthanitdoesforthesamegoodsolddomesticallyDumping42Dumpingcanoccuronlyiftwoconditionsaremet:ImperfectlycompetitiveindustrySegmentedmarketsGiventheseconditions,amonopolisticfirmmayfindthatitisprofitabletoengageindumping.Dumping43Figure6-8:DumpingDumpingExportsDomesticsalesCost,CandPrice,PQuantitiesproducedanddemanded,QMCDFOR=MRFORMRDOMDDOM2PFORPDOMQDOMQMONOPOLYTotaloutput1344ReciprocalDumpingAsituationinwhichdumpingleadstotwo-waytradeinthesameproductItincreasesthevolumeoftradeingoodsthatarenotquiteidentical.Itsnetwelfareeffectisambiguous:Itwastesresourcesintransportation.Itcreatessomecompetition.Dumping45TheTheoryofExternalEconomiesEconomiesofscalethatoccurattheleveloftheindustryinsteadofthefirmarecalledexternaleconomies.Therearethreemainreasonswhyaclusteroffirmsmaybemoreefficientthananindividualfirminisolation:SpecializedsuppliersLabormarketpoolingKnowledgespillovers46SpecializedSuppliersInmanyindustries,theproductionofgoodsandservicesandthedevelopmentofnewproductsrequirestheuseofspecializedequipmentorsupportservices.Anindividualcompanydoesnotprovidealargeenoughmarketfortheseservicestokeepthesuppliersinbusiness.Alocalizedindustrialclustercansolvethisproblembybringingtogethermanyfirmsthatprovidealargeenoughmarkettosupportspecializedsuppliers.ThisphenomenonhasbeenextensivelydocumentedinthesemiconductorindustrylocatedinSiliconValley.TheTheoryofExternalEconomies47LaborMarketPoolingAclusteroffirmscancreateapooledmarketforworkerswithhighlyspecializedskills.Itisanadvantagefor:ProducersTheyarelesslikelytosufferfromlaborshortages.WorkersTheyarelesslikelytobecomeunemployed.TheTheoryofExternalEconomies48KnowledgeSpilloversKnowledgeisoneoftheimportantinputfactorsinhighlyinnovativeindustries.Thespecializedknowledgethatiscrucialtosuccessininnovativeindustriescomesfrom:ResearchanddevelopmenteffortsReverseengineeringInformalexchangeofinformationandideasTheTheoryofExternalEconomies49ExternalEconomiesandIncreasingReturnsExternaleconomiescangiverisetoincreasingreturnstoscaleatthelevelofthenationalindustry.Forward-fallingsupplycurveThelargertheindustry’soutput,thelowerthepriceatwhichfirmsarewillingtoselltheiroutput.TheTheoryofExternalEconomies50ExternalEconomiesandthePatterofTradeAcountrythathaslargeproductioninsomeindustrywilltendtohavelowcostsofproducingthatgood.Countriesthatstartoutaslargeproducersincertainindustriestendtoremainlargeproducersevenifsomeothercountrycouldpotentiallyproducethegoodsmorecheaply.Figure6-9illustratesacasewhereapatternofspecializationestablishedbyhistoricalaccidentispersistent.ExternalEconomiesandInternationalTrade51Figure6-9:ExternalEconomiesandSpecializationExternalEconomiesandInternationalTradeACSWISSQ1P1Price,cost(perwatch)QuantityofwatchesproducedanddemandedACTHAI21C0D52TradeandWelfarewithExternalEconomiesTradebasedonexternaleconomieshasmoreambiguouseffectsonnationalwelfarethaneithertradebasedoncomparativeadvantageortradebasedoneconomiesofscaleatthelevelofthefirm.AnexleofhowacountrycanactuallybeworseoffwithtradethanwithoutisshowninFigure6-10.ExternalEconomiesandInternationalTrade53Figure6-10:ExternalEconomiesandLossesfromTradeExternalEconomiesandInternationalTradeACSWISSP1Price,cost(perwatch)QuantityofwatchesproducedanddemandedACTHAI21C0DTHAIDWORLDP254DynamicI