经济学（微观）（英文版原书第7版）课件 第14章　寡头垄断：竞争不充分市场中的企业

EconomicsSeventhEditionChapter14Oligopoly:FirmsinLessCompetitiveMarketsCopyright©2019,2017,2015PearsonEducation,Inc.AllRightsReserved.ChapterOutline14.1

OligopolyandBarrierstoEntry14.2

GameTheoryandOligopoly14.3

SequentialGamesandBusinessStrategy14.4

TheFiveCompetitiveForcesModelOligopoly:aVeryDifferentMarketStructureInthepreviouschapters,weexaminedperfectandmonopolisticcompetition.Thesetwomarketstructuresweresimilar:firmsproduceuntiltheirmarginalcostisequaltomarginalrevenue,andthelowbarrierstoentrywouldresultinprofitbeingcompetedawayinthelongrun.Oligopoly,amarketstructureinwhichasmallnumberofinterdependentfirmscompete,willrequirecompletelydifferenttoolstoanalyze.Why?Oligopolistsarelargeandknowthattheiractionshaveaneffectononeanother.Barrierstoentryexist,preventingfirmsfromcompetingawayprofits.14.1OligopolyandBarrierstoEntryShowhowbarrierstoentryexplaintheexistenceofoligopolies.Beforeweanalyzehowoligopolistsbehave,itisusefultoknowwhichfirms/marketswearediscussing.Ausefultoolforidentifyingthetypeofmarketstructureisthefour-firmconcentrationratio:thefractionofanindustry’ssalesaccountedforbyitsfourlargestfirms.Afour-firmconcentrationratiolargerthan40percenttendstoindicateanoligopoly.Althoughtherearelimitstohowusefulfour-firmconcentrationratioscanbe,theyareausefultoolindiscussingtheconcentrationofmarketpowerwithinanindustry.Table14.1ExamplesofOligopoliesinRetailTradeandManufacturingRetailTradeblackManufacturingblackIndustryFour-FirmConcentrationRatioIndustryFour-FirmConcentrationRatioDiscountdepartmentstores(WalmartandTarget)97%Cigarettes(PhillipMorrisandR.J.Reynolds)98%Warehouseclubsandsupercenters(Sam’sClubandBJ’sWholesaleClub)94%Beer(Anheuser-BuschandMillerCoors)90%Collegebookstores(Barnes&NobleandFollett)75%Computers(Hewlett-PackardandDell)87%Hobby,toy,andgamestores(Toys“R”UsandMichael’s)72%Aircraft(BoeingandLockheedMartin)81%Radio,television,andotherelectronicstores(BestBuyandApple)70%Breakfastcereal(Kellogg’sandGeneralMills)80%Athleticfootwearstores(FootlockerandChamps)68%Dogandcatfood(MarsandProcter&Gamble)71%Pharmaciesanddrugstores(WalgreensandCVSCaremark)63%Automobiles(GeneralMotorsandFord)68%LimitationsofFour-FirmConcentrationRatiosFour-firmconcentrationratiosareagoodfirstlookatcompetitioninanindustry;above40percentindicatesanoligopolytomanyeconomists.Buttheyhavesomeweaknesses:TheydonotincludethegoodsandservicesthatforeignfirmsexporttotheUnitedStates.Theyarecalculatedfornationalmarkets,evenifthemarketisreallylocal(likethecollegebookstoremarket).Thedefinitionofthemarketistricky:Walmartisinthe“discountdepartmentstore”category,butreallyalsocompetesagainstsupermarketsandotherstores.WhyDoOligopoliesExist?Oligopoliesoftenexistbecauseofbarrierstoentry:anythingthatkeepsnewfirmsfromenteringanindustryinwhichfirmsareearningeconomicprofits.Themostimportantbarriertoentryiseconomiesofscale:thesituationwhenafirm’slong-runaveragecostsfallasthefirmincreasesoutput.Thiscanmakeitdifficultfornewfirmstoenteramarket,becausenewfirmsusuallyhavetostartsmallandwillhencehavesubstantiallyhigheraveragecoststhanestablishedfirms.Figure14.1EconomiesofScaleHelpDeterminetheExtentofCompetitioninanIndustryIflong-runaveragecostisminimizedatasmallfractionofindustryoutput,asonLRAC1,thereisroomintheindustryformanyfirms.Butifittakesalarge(relativetoindustrysize)firmtoachieveeconomiesofscale,themarketismorelikelytobeanoligopoly.OtherReasonsforOligopoliesExisting(1of2)OwnershipofakeyinputIfcontrolofakeyinputisheldbyoneorasmallnumberoffirms,itwillbedifficultforadditionalfirmstoenter.Examples: Alcoa—bauxiteforaluminumproductionDeBeers—diamondsOceanSpray—cranberriesOtherReasonsforOligopoliesExisting(2of2)Government-imposedbarriersGovernmentsmightgrantexclusiverightstosomeindustrytooneorasmallnumberoffirms.Examples:Occupationallicensing(ex:dentistsanddoctors)PatentsTariffsandquotasimposedonforeigncompaniesPatent:Theexclusiverighttoaproductforaperiodof20yearsfromthedatethepatentisfiledwiththegovernment.ApplytheConcept:Don’tTrySellingHomemadeCookiesinWIandNJInWisconsinandNewJersey,bakedgoodsmayonlybesoldiftheyarepreparedinacommercialkitchen.Doyouthinktheselawsexistprimarilytoprotectpublichealth,ortodecreasecompetitionfortraditionalbakeries?14.2GameTheoryandOligopolyUsegametheorytoanalyzethestrategiesofoligopolisticfirms.Unlikeperfectandmonopolisticcompetitors,oligopolistsarelargerelativetothemarket,andtheactionsofoneoligopolistmakelargedifferencesintheprofitsofanother.Sographicalanalysisofonefirm’sactionswillnotcapturethenuancesofanoligopolisticmarket.Oligopoliesarebestanalyzedusingaspecializedfieldofstudycalledgametheory.Gametheory:Thestudyofhowpeoplemakedecisionsinsituationsinwhichattainingtheirgoalsdependsontheirinteractionswithothers;ineconomics,thestudyofthedecisionsoffirmsinindustrieswheretheprofitsofafirmdependonitsinteractionswithotherfirms.GameTheoryGametheorywasdevelopedduringthe1940sandadvancedbymathematiciansandeconomistsandothersocialscientists.All“games”sharecertaincharacteristics:RulesthatdeterminewhatactionsareallowableStrategiesthatplayersemploytoattaintheirobjectivesinthegamePayoffsthataretheresultsoftheinteractionsamongtheplayers’strategiesForexample,wecanmodelfirmproductionasa“game”:Rules:theproductionfunctionsandmarketdemandcurveStrategies:firms’productiondecisionsPayoffs:firms’profitsFigure14.2ADuopolyGame(1of5)SupposeSpotifyandApplearetheonlytwofirmssellingstreamingmusicservice.Eachmustchoosetheirbusinessstrategy:actionsthatafirmtakestoachieveagoal,suchasmaximizingprofits.Assumeeachfirmcanchargeeither$14.99or$9.99.Thecombinationofstrategieschosendeterminesprofit,shownintheabovepayoffmatrix:atablethatshowsthepayoffsthateachfirmearnsfromeverycombinationofstrategiesbythefirms.Figure14.2ADuopolyGame(2of5)SupposeyouareSpotifyinthisgame.Howwouldyouplay?IfApplecharges$14.99,youearn$10mprofitbycharging$14.99or$15mprofitbycharging$9.99.Youprefer$9.99.IfApplecharges$9.99,youearn$5mprofitbycharging$14.99or$7.5mprofitbycharging$9.99.Youprefer$9.99.Charging$9.99isadominantstrategyforSpotify:astrategythatisthebestforafirm,nomatterwhatstrategiesotherfirmsuse.Figure14.2ADuopolyGame(3of5)NowsupposeyouareApple.Howwouldyouplay?IfSpotifycharges$14.99,youearn$10mprofitbycharging$14.99or$15mprofitbycharging$9.99.Youprefer$9.99.IfSpotifycharges$9.99,youearn$5mprofitbycharging$14.99or$7.5mprofitbycharging$9.99.Youprefer$9.99.Charging$9.99isadominantstrategyforApplealso.Figure14.2ADuopolyGame(4of5)Bothfirmscharging$9.99isaNashequilibrium:asituationinwhicheachfirmchoosesthebeststrategy,giventhestrategieschosenbytheotherfirm.Thefirmsdon’thavetohavedominantstrategiesinorderfortheretobeaNashequilibrium;theirstrategiesjusthavetobebestresponsestooneanother’sstrategies.Figure14.2ADuopolyGame(5of5)Noticethatbothfirmscoulddobetterviacollusion:anagreementamongfirmstochargethesamepriceorotherwisenottocompete.Ifbothfirmscharge$14.99,theyachievemoreprofitthanbyactingindependently.CollusionisagainstthelawintheUnitedStatesandEurope,butyoucanseewhyfirmsmightbetemptedtocollude:theirprofitscouldbesubstantiallyhigher.CooperativeEquilibriumvs.NoncooperativeEquilibriumNashequilibriumisanexampleofanoncooperativeequilibrium:anequilibriuminagameinwhichplayersdonotcooperatebutpursuetheirownself-interest.Manygametheoristsconcentrateonnoncooperativeequilibrium,particularlybecauseoflawsagainstcooperationamongfirms.Ifweallowedplayerstocoordinatetheiractionsinagame,byformingalliancesetc.,wewouldbelookingforacooperativeequilibrium:anequilibriuminagameinwhichplayerscooperatetoincreasetheirmutualpayoff.Thismightmakesenseformanysocialinteractions:groupsofpeopleoftentrytocooperateratherthanworkindependently.Prisoner’sDilemmaEconomistsandothersocialscientistsrefertothesituationwithSpotifyandAppleasaprisoner’sdilemma:agameinwhichpursuingdominantstrategiesresultsinnoncooperationthatleaveseveryoneworseoff.Thenamecomesfromaproblemfacedbytwosuspectsthepolicearrestforacrime.Thepoliceoffereachsuspectasuspendedprisonsentenceinexchangeforconfessingtothecrimeandtestifyingagainsttheothersuspect.Eachsuspecthasadominantstrategytoconfess.Ifbothconfess,theybothgotojailforalongtime,whiletheybothcouldhavegonetojailforashorttimeiftheyhadbothremainedsilent.Figure14.3ChangingthePayoffMatrixinaRepeatedGameSupposeDomino’sandPizzaHutaredecidinghowtopriceapizza:$12or$10.Thisgamegetsplayednotoncebuteveryday.Acleverwaytoavoidthelow-profitNashequilibriumistoadvertiseapricematchguarantee.Thenifeitherfirmcutsprices,theotherhasguaranteedtodosoaswell.Nowneitherfirmwillhaveanincentivetocutprices.Dopricematchguaranteesreallybenefitconsumers?OtherMethodsforAvoidingPriceCompetitionApricematchguaranteeisanenforcementmechanism,makingautomaticthedecisionaboutwhethertopunishacompetingfirmforchargingalowprice.Anothermethodispriceleadership,aformofimplicitcollusioninwhichonefirminanoligopolyannouncesapricechangeandtheotherfirmsintheindustrymatchthechange.Example:Inthe1970s,GeneralMotorswouldannounceapricechangeatthebeginningofamodelyear,andFordandChryslerwouldmatchGM’spricechange.ApplytheConcept:AretheBigFourAirlinesColluding?Mergersintheairlineindustryhaveincreasedthepossibilityofimplicitcollusion.Decreasingfuelcostsmadeflightsmoreprofitable,buttopairlinemanagersallannouncedtheywouldundertakeonlymodestincreasesincapacity.TheDepartmentofJusticeinvestigatedfrom2015to2017,butdecidednottobringcollusionchargesagainsttheairlines.Figure14.4OilPrices,1972tomid-2017Acartelisagroupoffirmsthatcolludebyagreeingtorestrictoutputtoincreasepricesandprofits.TheOrganizationofPetroleumExportingCountriesisthebestknowncartel.OPECcolludedtorestrictoutputandraisepricesinthe1970sand1980s.Butcollusionhasproveddifficulttomaintainovertime.Figure14.5TheOPECCartelwithUnequalMembersBecauseSaudiArabiacanproducemuchmoreoilthanNigeria,itsoutputdecisionshaveamuchlargereffectonthepriceofoil.SaudiArabiahasadominantstrategytocooperateandproducealowoutput.Nigeria,however,hasadominantstrategynottocooperateandinsteadproduceahighoutput.InordertopunishNigeriafordefecting,SaudiArabiawouldhavetohurtitselfsubstantially.Woulditbeworthittoyou?14.3SequentialGamesandBusinessStrategyUsesequentialgamestoanalyzebusinessstrategies.Thegametheorymodelswehaveanalyzedsofarhavebeensimultaneous:theplayershavemadetheirdecisionsatthesametime.Butsomegamesaresequentialinnature:onefirmmakesadecision,andtheothermakesitsdecisionhavingobservedthefirstfirm’sdecision.Weanalyzesuchgamesusingadecisiontree,indicatingwhogetstomakeadecisionatwhatpoint,andwhattheconsequencesoftheirdecisionwillbe.Figure14.6TheDecisionTreeforanEntryGameAppledecideswhethertocharge$1,000or$800foranewlaptop.ThenDelldecidestoenterthemarketornot,needinga15percentreturn.IfApplecharges$1,000,Dellwillwanttoenter;itsreturnexceeds15percent.IfApplechargesthelowprice,Dellwillnotwanttoenter.SoApplecandeterDellfromenteringthemarketbycharging$800.Figure14.7TheDecisionTreeforaBargainingGame(1of2)Dellcanoffer$20or$30percopyforTruImage’ssoftware.ThenTruImagecanacceptorrejecttheoffer.DellwilllookaheadandrealizethatTruImageisbetteroffacceptingDell’soffer,nomatterwhatpriceDelloffers.ThereforeDellshouldofferthelowprice,anticipatingthatTruImagewillaccepttheoffer.Figure14.7TheDecisionTreeforaBargainingGame(2of2)NoticethatTruImagewouldliketothreatentorejectanofferof$20.IfDellbelievedthethreat,itsbestactionwouldbetooffer$30.ButDellshouldn’tbelievethethreat;itisnotcredible.Onlytheoriginaloutcomeisasubgame-perfectequilibrium:wherenoplayercanimprovetheiroutcomebychangingtheirdecisionatanydecisionnode.14.4TheFiveCompetitiveForcesModel(1of2)Usethefivecompetitiveforcesmodeltoanalyzecompetitioninanindustry.MichaelPorterofHarvardBusinessSchoolidentifiesfiveseparatecompetitiveforcesthatdeterminetheoveralllevelofcompetitioninanindustry:CompetitionfromexistingfirmsExa