微觀經濟學 Chapter-10-助教張翔

Chapter10

OligopolyandMonopolisticCompetition

黃新飛

InternationalBusinessSchoolSun－YatSenUniversity2MarketPowerMarketpowersignifiesthedegreeofcontrolthatafirmorasmallnumberoffirmshasoverthepriceandproductiondecisionsinanindustry.Themostcommonmeasureofmarketpoweristhefour-firmconcentrationratio.3FirmOutputFirm1 25Firm2 20Firm3 15Firm4 10Firm5 8Firm6 7Firm7 5Firm8 5Firm9 3Firm10 2=70Four-FirmConcentrationRatioConcentrationRatios:

c4=

q1+q2+q3+q425+20+15+10100Q==70%4CigarettesHouseholdrefrigeratorsElectriclightbulbsMotorvehiclesGreetingcardsBlastfurnacesScrewproducts5%_4%Tools,dies,andjigs3%_2%93%82%86%84%84%37%7%16%8%7%4%21%4largestcompaniesNext4largestcompanies5WarningonConcentrationConventionalconcentrationmeasuresincludeonlydomesticproductionandexcludeimports.Conventionalconcentrationmeasuresalsoignorethegrowingimpactofcompetitionfromotherindustries.6TheNatureofImperfectCompetitionEconomistshavefoundthatthreemajorfactorsarepresentinimperfectlycompetitivemarkets:CostsBarrierstocompetitionStrategicinteraction

(策略互動)7 Percentageofindustry outputproducedbythe

Industry fourlargestfirms.ChewingGum 96% Householdlaundryequipment 93Cigarettes 92Electriclamps(bulbs) 91Motorvehicles 90Smallarmsammunition 88Primarycopper 87Breakfastcereals 87Beerandmaltbeverages 87Householdrefrigerators 85Greetingcardpublishing 85Bookpublishing 24% Upholsteredfurniture 24Woodfurniture 20Metalhousefurniture 18Paperboardboxes 16Bolts,nuts,andrivets 16Furgoods 16Women’sandmisses’suitsandcoats 13Metaldoors 13Women’sandmisses’dresses 6OligopolyMonopolisticCompetition8StrategicInteractionDescribeshoweachfirm’sbusinessstrategydependsontheirrivals’strategies.Asthenumberoffirmsinanindustryshrinksandindustryconcentrationgrows,eachfirmismorelikelytobasepricingandoutputdecisionsonhowotherfirmsintheindustryarelikelytorespond.9TheoriesofImperfectCompetitionThreeofthemostimportantcasesofimperfectcompetition:Collusiveoligopoly(合謀寡頭)MonopolisticcompetitionSmall-numberoligopoly10CooperativeandNoncooperativeBehaviorWhenthereareonlyasmallnumberoffirmsinamarket,theyhaveachoicebetweencooperative

(合作)andnoncooperative

(非合作)behavior.中國案例分析：華為侵權案7月28日，華為公司、思科公司、3COM公司向得克薩斯州東區(qū)法院馬歇爾分院提交了終止訴訟的申請，法院遂簽發(fā)法令，終止了思科對華為的訴訟。一個是全球最大的網(wǎng)絡設備制造商，一個是中國年輕的網(wǎng)絡設備制造商。思科占據(jù)著全球壟斷性地位，市值1000多億美元，年收入近200億美元。在這場全球化的殘酷對決中，華為孤軍作戰(zhàn)且創(chuàng)造了“神話”，和解其實就已經是勝利。12CollusionCollusionoccurswhenoneormorefirmsjointly(共同地)setpricesoroutputs,dividethemarketamongthemselves,ormakeotherbusinessdecisionsjointly.Suchcollusioncanbeeitherexplicitortacit(公開的或默許的).13ExplicitCollusiveOneexampleofexplicit(清楚的，公開的)collusionwouldbethatoftheGildedAgeoligopolists(市場供應壟斷者)intheearlyyearsofAmericancapitalism.Theseoligopolistsformedtrustsorcartels(托拉斯或卡特爾)tosetprices.TheAntitrustLaws14In1960,someexecutivesatGeneralElectric,Westinghouse,andAllis-Chalmers,amongothers,cookedupaschemetofixpricesinthemarketforheavyelectricalequipmentsuchastransformers,turbines,andcircuitbreakers.PhasesoftheMoonConspiracy15MorePricingFixingIn1993,Borden,Incorporatedpaid$8millioninfinesforfixingbidsonmilksoldtoschools.Bristol-MeyersSquibbandAmericanHomeProductspaid$5millionin1992tosettlechargesthattheyhadfixedpricesonbabyformulas.16ColaAndFaxPaperInacolawarmeltdown,localexecutivesforbothCocaColaandPepsiCowenttoprisonforconspiringtofixsoft-drinkpricesinVirginia.Mitsubishipledguiltyandpaida$1.8millionfineforconspiringtoraisethepriceoffaxpaper.17PriceLeaderTacitCollusionThebroaderproblemiswithimplicitortacitcollusionthatarisespreciselybecauseexplicitcollusionisillegal.Thewordtacitmeansto“expressorcarryonwithoutwordsorspeech.”

Andtacitcollusionissaidtooccurwhenfirmsinanindustryrefrainfromcompetitionwithoutexplicitagreements.18BarriersFirst,collusionisillegal.Second,firmsmay“cheat”ontheagreementbycuttingtheirpricetoselectedcustomers.Third,manycompaniesfaceintensivecompetitionfromforeignfirmsaswellasdomesticcompanies.19ThreeBasicModelsCartelPriceLeaderKinkedDemandDQPTheKinkedDemandTheory元/數(shù)量數(shù)量MRD如果廠商降低價格，其他廠商也會跟著降低價格，結果，需求相對缺乏彈性。如果廠商將價格提高到P*之上，其他廠商不會提高價格，則需求變得富有彈性。P*AE美元/數(shù)量DP1Q1MCMC’只要MC仍然在MR的垂直區(qū)域內，那么，價格與產量仍保持不變。MR數(shù)量AEBN折彎的需求曲線22ANegotiatedPriceTheythennegotiatewhatpriceshouldbechargedfortheproduct.And,ofcourse,aspartoftheirsecretcartelagreement,eachfirmwillalsohavetoagreetorestrictitsoutputsothepricecanbemaintainedinthemarket.23AQuestionSowheredoyouthinktheseoligopolistswillsetprice?

a)Theoligopolywillsetpriceequaltomarginalcost.b)Theoligopolywillsetmarginalrevenueequaltomarginalcost.c)Thisisanincrediblyobscurequestion.24TheAnswerSowheredoyouthinktheseoligopolistswillsetprice?

a)Theoligopolywillsetpriceequaltomarginalcost.b)Theoligopolywillsetmarginalrevenueequaltomarginalcost.c)Thisisanincrediblyobscurequestion.Iftheoligopolistscantrulycoordinatetheiractivities,theobviouspricetosetisthesameasthatwhichwouldbesetbyamonopolist.25CheatingValue產量如果其他人保持價格不變搞欺騙的企業(yè)的好處價格如果所有企業(yè)價格同時變化課堂測試：古諾模型雙寡頭模型假設市場需求曲線P=30–Q，并且Q=Q1+Q2MC1=MC2=0如何推導廠商1和2的反應曲線27MonopolisticCompetitionMonopolisticcompetitionresemblesperfectcompetitioninthreeways:1.Theremanybuyersandsellers,2.Entryandexitareeasy,3.Firmstakeotherfirms’pricesasgiven.28ProductDifferentiationThedifferencefromperfectcompetitionisproductdifferentiation

(產品差異).Productdifferentiationleadstoadownwardslopeineachseller’sdemandcurve.29MonopolisticCompetitionVSoligopolyTherearethreekeydifferencesbetweenoligopolyandmonopolisticcompetition.1.Amonopolisticallycompetitiveindustryisrelativelyunconcentrated.2.Collusionsareimpossible.3.Thereisnofeelingofmutualinterdependenceamongfirms.30PriceMCACWhatisthepriceandquantityinthisindustryandwhataretheeconomicprofits?a)PriceisP1,quantityisQ1andeconomicprofitsareBHG.PriceissetwhereMCintersectsdd.b)PriceisP2,quantityisQ2,andeconomicprofitsareP1P2GB.PriceissetwhereMRequalsMC.c)IfIhadacomputer,Icouldfigureitout.MonopolisticcompetitionbeforeentryP2P1GdBMRHd31PriceMCACWhatisthepriceandquantityinthisindustryandwhataretheeconomicprofits?a)PriceisP1,quantityisQ1andeconomicprofitsareBHG.PriceissetwhereMCintersectsdd.b)PriceisP2,quantityisQ2,andeconomicprofitsareP1P2GB.PriceissetwhereMRequalsMC.c)IfIhadacomputer,Icouldfigureitout.MonopolisticcompetitionbeforeentryP2P1GdBMRHd32ACd'd'MCdPriceAtwhatpointwillentrycease?a)Entrywillceasewheneachsellerhasbeenforcedintoalong-run,no-profittangencysuchasatG'.b)EntrywillceasewhereMCequalsAC.c)EntrywillceasewhenBillGatessaysitwill.MonopolisticcompetitionafterentryddG’MR33ACd'd'MCdPriceAtwhatpointwillentrycease?a)Entrywillceasewheneachsellerhasbeenforcedintoalong-run,no-profittangencysuchasatG'.b)EntrywillceasewhereMCequalsAC.c)EntrywillceasewhenBillGatessaysitwill.MonopolisticcompetitionafterentryddG’MR34ACd'd'MCdPriceMonopolisticcompetitionafterentryddG’MRP1P=MCEachproducerisontheleft-handdecliningbranchofitslongrunaveragecostcurve.Whatdoyouthinkthismeansformarketperformance.35ACd'd'MCdPriceMonopolisticcompetitionafterentryddG’MRP1P=MCAInthelongrun,monopolisticcompetitionisneitherallocativelyorproductivelyefficient.Anunderallocationofresourcesoccursintheindustrybecausetheproductpriceexceedsmarginalcost.ProductiveefficiencyisnotrealizedbecauseproductionoccursatpointG'wheretheaveragetotalcostexceedstheminimumattainablecostatPointA.36Non-PriceandAggressiveAdvertisingThefactthatthatmonopolisticcompetitionisbothallocativelyandproductivelyinefficientrelativetotheperfectcompetitionresultisnottheonlyproblemwithmarketperformance.AtleastsomeeconomistsarguethatmonopolisticcompetitionleadstobothexcessiveadvertisingandneedlessbrandproliferationReducingthenumberofmonopolisticcompetitors,whilecuttingcosts,mightwellenduploweringconsumerwelfarebecauseitwouldreducethediversity(多樣性)ofavailablegoodsandservices.37GameTheoriesCompetitionamongthefewforcesfirmstotakeintoaccountcompetitors’reactionstopriceandoutputdeviations(背離)andbringsstrategic(戰(zhàn)略的)considerationsintotheirmarkets.Thisanalysisistheprovinceofgametheory(博弈論).38DivorceofOwnershipandControlIn1996,morethan2.3millionpeopleownedAT&T’sshares.Becausethestockoflargecompaniesissowidelydispersed(被分散的),ownershipistypicallydivorcedfromcontrol.ThreeConflictsofInterest39RationalityandRulesofThumbIntherealworld,peoplehavelimitedresourcesandinformationtomakedecisions,sofirmsorconsumersoftenexhibitboundedrationality(有限理性).Thismeansthattheyusuallystrivetomakeagooddecision,ratherthanwasteresourceshuntingfor(追逐)thebestdecision.40TheEconomicsofInformationBecauseinformationiscostlytoproducebutcheaptoreproduce,marketsininformationaresubjecttoseveremarketfailures(市場失靈).Theinabilityoffirmstocapturethefullmonetaryvalueoftheirinventions(發(fā)明)iscalledinappropriability(非專用性).IntellectualPropertyRight41AreMonopoliesBad?ThequestionfirstraisedbyHarvardeconomistJosephSchumpeteriswhethermonopoliesarelikelytooutperformcompetitiveindustriesinthedynamicefficiencydimension.Iftheanswerisyes,thenperhapsweshouldjustleavemonopoliesalone.JosephSchumpeter1883-195042IndustrialR&DPerformanceBySizeofCompanySizeofCompanyR&D-SalesRatio(%)TotalCompanyR&D（$,billions）

1999(employees)19831999Fewerthan5002.28.931.3500to999na4.06.41,000to4,9992.03.123.95,000to9,9910,000to24,9992.32.824.525,000ormore3.42.059.9課堂測試假設（1）只有A、B寡頭廠商出售同質且生產成本為零的產品；（2）市場對該產品的需求函數(shù)為Q=240-10P；（3）廠商A先進入市場，隨著B進入。各廠商確定產量時認為另一廠商會保持產量不變。試求：a.均