Chap-17垄断竞争(经济学原理 中英文双语)

Chap_17垄断竞争(经济学原理中英文双语)MonopolisticCompetition

垄断竞争Imperfectcompetitionreferstothosemarketstructuresthatfallbetweenperfectcompetitionandpuremonopoly.

不完全竞争是指介于完全竞争与纯垄断之间的市场结构。TheFourTypesofMarketStructureMonopoly（Chap15）Oligopoly(Chap16)MonopolisticCompetition(Chap17)PerfectCompetition（Chap14）

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WheatMilkNumberofFirms?TypeofProducts?ManyfirmsOnefirmFewfirmsDifferentiatedproductsIdenticalproducts市场结构的四种类型垄断（15章）寡头（16章）垄断竞争（17章）完全竞争（14章）自来水

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牛奶企业数量?产品类型？许多企业一家企业几家企业有差别产量相同产品TypesofImperfectlyCompetitiveMarketsMonopolisticCompetition

Manyfirmssellingproductsthataresimilarbutnotidentical.OligopolyOnlyafewsellers,eachofferingasimilaroridenticalproducttotheothers.不完全竞争市场的类型垄断竞争

许多出售相似但不相同产品的企业组成的市场结构。寡头只有很少卖者，出售相似或相同的产品。MonopolisticCompetition

垄断竞争Marketsthathavesomefeaturesofcompetitionandsomefeaturesofmonopoly.有某些竞争特点又有某些垄断特点的市场结构。AttributesofMonopolisticcompetition

垄断竞争的特点Manysellers

很多卖者Productdifferentiation

产品有差异Freeentryandexit

自由进入和退出ManySellersTherearemanyfirmscompetingforthesamegroupofcustomers.Productexlesincludebooks,CDs, movies,computergames,restaurants, pianolessons,cookies,furniture,etc.很多卖者有许多企业争夺同样的顾客群体。产品例子包括书籍、CD、电影、电脑游戏、餐馆、钢琴课、点心、家居等等。ProductDifferentiationEachfirmproducesaproductthatisatleastslightlydifferentfromthoseofotherfirms.Ratherthanbeingapricetaker,eachfirmfacesadownward-slopingdemandcurve.产品差异化每个企业生产的一种产品至少与其他企业生产的这种产品略有不同。每个企业不是价格接受者，而是面临一条向右下方倾斜的需求曲线。FreeEntryorExitFirmscanenterorexitthemarketwithoutrestriction.Thenumberoffirmsinthemarketadjustsuntileconomicprofitsarezero.自由进入或退出企业可以没有限制地进入或退出一个市场。市场上企业的数量要一直调整到经济利润为零时为止。MonopolisticCompetitionintheShortRunShort-runeconomicprofitsencouragenewfirmstoenterthemarket.This:Increasesthenumberofproductsoffered.Reducesdemandfacedbyfirmsalreadyinthemarket.Incumbentfirms’demandcurvesshifttotheleft.Demandfortheincumbentfirms’productsfall,andtheirprofitsdecline.短期中的垄断竞争企业短期经济利润激励新企业进入市场。这种进入增加了顾客可以选择的产品数量。减少了市场已有的每家企业面临的需求。使市场已有企业面临的需求曲线向左移动。市场已有企业的产品需求减少，利润下降。Figure1MonopolisticCompetition

intheShortRunQuantity0PriceProfit-maximizingquantityPriceDemandMRATC(a)FirmMakesProfitAveragetotalcostProfitMC图1.短期中的垄断竞争企业(a)企业有利润产量0价格需求MRATC利润MC利润最大化产量价格平均总成本MonopolisticCompetitionin

theShortRunShort-runeconomiclossesencouragefirmstoexitthemarket.This:

Decreasesthenumberofproductsoffered.Increasesdemandfacedbytheremainingfirms.Shiftstheremainingfirms’demandcurvestotheright.Increasestheremainingfirms’profits.短期中的垄断竞争企业短期经济亏损激励企业退出市场。随着企业退出：

顾客可选择的产品数量少了。增加了继续留在市场中的企业面临的需求。使继续留在市场中的企业的需求曲线向右移动。使继续留在市场中的企业的利润增加。Figure1MonopolisticCompetitors

intheShortRunDemandQuantity0PricePriceLoss-minimizingquantityAveragetotalcost(b)FirmMakesLossesMRLossesATCMC图1.短期中的垄断竞争企业产量0价格需求MR亏损(b)企业亏损MCATC平均总成本利润最小化产量价格TheLong-RunEquilibrium

长期均衡Firmswillenterandexituntilthefirmsaremakingexactlyzeroeconomicprofits.企业进入或退出的过程一直持续到市场中的企业的经济利润正好是零时。Figure2AMonopolisticCompetitor

intheLongRunQuantityPrice0DemandMRATCMCProfit-maximizingquantityP=ATC图2.长期中的垄断竞争者产量价格0需求MRATCMC利润最大化产量P=ATCLong-RunEquilibriumTwoCharacteristicsAsinamonopoly,priceexceedsmarginalcost.Profitmaximizationrequiresmarginalrevenuetoequalmarginalcost.Thedownward-slopingdemandcurvemakesmarginalrevenuelessthanprice.Asinacompetitivemarket,priceequalsaveragetotalcost.Freeentryandexitdriveeconomicprofittozero.长期均衡两个特点正如在垄断市场上一样，价格大于边际成本。利润最大化要求边际收益等于边际成本。向右下方倾斜的需求曲线使边际成本小于价格。正如在竞争市场上一样，价格等于平均总成本。自由进入与退出使经济利润为零。MonopolisticversusPerfectCompetitionTherearetwonoteworthydifferencesbetweenmonopolisticandperfectcompetition—excesscapacityandmarkup.垄断竞争与完全竞争垄断竞争和完全竞争之间有两个值得注意的差别—过剩生产能力和价格加成。MonopolisticversusPerfectCompetitionExcessCapacityThereisnoexcesscapacityinperfectcompetitioninthelongrun.Freeentryresultsincompetitivefirmsproducingatthepointwhereaveragetotalcostisminimized,whichistheefficientscaleofthefirm.Thereisexcesscapacityinmonopolisticcompetitioninthelongrun.Inmonopolisticcompetition,outputislessthantheefficientscaleofperfectcompetition.垄断竞争与完全竞争过剩生产能力在长期中，完全竞争企业没有过剩生产能力。竞争市场上的自由进入使企业生产平均总成本最小的产量，即企业的有效规模产量。在长期中，垄断竞争企业存在过剩生产能力。垄断竞争企业的产量低于完全竞争企业生产的有效规模产量。Figure3MonopolisticversusPerfectCompetitionQuantity0PriceDemand(a)MonopolisticallyCompetitiveFirmQuantity0PriceP=MCP=MR(demandcurve)(b)PerfectlyCompetitiveFirmMCATCMCATCMREfficientscalePQuantityproducedQuantityproduced=Efficientscale图3.

垄断竞争与完全竞争产量(a)垄断竞争企业(b)完全竞争企业产量价格P=MR(需求曲线)MCATC价格需求MCATC过剩生产能力生产量有效规模P=MC产量=有效规模产量PMonopolisticversusPerfectCompetitionMarkupOverMarginalCostForacompetitivefirm,priceequalsmarginalcost.Foramonopolisticallycompetitivefirm,priceexceedsmarginalcost.Becausepriceexceedsmarginalcost,anextraunitsoldatthepostedpricemeansmoreprofitforthemonopolisticallycompetitivefirm.垄断竞争与完全竞争高于边际成本的价格加成对一个竞争企业来说，价格等于边际成本。对一个垄断竞争企业来说，价格高于边际成本。因为垄断竞争企业的价格高于其边际成本，以牌价多销售出一个单位产品就意味着利润多了。Figure3MonopolisticversusPerfectCompetitionQuantity0PriceDemand(a)MonopolisticallyCompetitiveFirmQuantity0PriceP=MCP=MR(demandcurve)(b)PerfectlyCompetitiveFirmMarkupMCATCMCATCMRMarginalcostPQuantityproducedQuantityproduced图3.高于边际成本的价格加成产量(a)垄断竞争企业(b)完全竞争企业产量价格P=MCP=MR(需求曲线)MCATC生产量价格P需求边际成本MCATCMR价格加成生产量Figure3MonopolisticversusPerfectCompetitionQuantity0PriceDemand(a)MonopolisticallyCompetitiveFirmQuantity0PriceP=MCP=MR(demandcurve)(b)PerfectlyCompetitiveFirmMarkupExcesscapacityMCATCMCATCMRMarginalcostEfficientscalePQuantityproducedQuantityproduced=Efficientscale图3.垄断竞争和完全竞争产量(a)垄断竞争企业(b)完全竞争企业产量价格P=MR(需求曲线)MCATC生产量有效规模价格P需求MCATCP=MC过剩市场能力边际成本价格加成MR生产量=有效规模MonopolisticCompetitionandtheWelfareofSociety

垄断竞争与社会福利Monopolisticcompetitiondoesnothaveallthedesirablepropertiesofperfectcompetition.垄断竞争不具有完全竞争所具有的令人合意的特性。MonopolisticCompetitionandtheWelfareofSocietyThereisthenormaldeadweightlossofmonopolypricinginmonopolisticcompetitioncausedbythemarkupofpriceovermarginalcost.However,theadministrativeburdenofregulatingthepricingofallfirmsthatproducedifferentiatedproductswouldbeoverwhelming.垄断竞争与社会福利垄断竞争市场存在由于高于边际成本的价格加成所导致的正常的无谓损失。但是，管制所有生产差异产品的企业的管理负担将是巨大的。

MonopolisticCompetitionandtheWelfareofSocietyAnotherwayinwhichmonopolisticcompetitionmaybesociallyinefficientisthatthenumberoffirmsinthemarketmaynotbethe“ideal”one.Theremaybetoomuchortoolittleentry.垄断竞争与社会福利垄断竞争可能引起社会无效率的另一个方面是市场上的企业数量可能并不是“理想”的数量，可能有太多或太少的企业进入。MonopolisticCompetitionandtheWelfareofSociety

垄断竞争与社会福利Externalitiesofentryinclude:进入的外部性包括：product-varietyexternalities.

产品多样化外部性

business-stealingexternalities.

抢走业务的外部性MonopolisticCompetitionand

theWelfareofSocietyTheproduct-varietyexternality:Becauseconsumersgetsomeconsumersurplusfromtheintroductionofanewproduct,entryofanewfirmconveysapositiveexternalityonconsumers.Thebusiness-stealingexternality:Becauseotherfirmslosecustomersandprofitsfromtheentryofanewcompetitor,entryofanewfirmimposesanegativeexternalityonexistingfirms.垄断竞争与社会福利产品多样化外部性:由于消费者从新产品引进中得到了一些消费者剩余，所以存在与进入相关的正外部性。抢走业务的外部性:由于其它企业从与新进入者的竞争者中失去顾客和利润，所以存在与进入相关的负外部性。Advertising广告Whenfirmsselldifferentiatedproductsandchargepricesabovemarginalcost,eachfirmhasanincentivetoadvertiseinordertoattractmorebuyerstoitsparticularproduct.当企业销售有差异产品并收取高于边际成本的价格时，每个企业都有靠做广告来吸引更多顾客购买自己特殊产品的激励。AdvertisingFirmsthatsellhighlydifferentiatedconsumergoodstypicallyspendbetween10and20percentofrevenueonadvertising.Overall,about2percentoftotalrevenue,orover$100billionayear,isspentonadvertising.广告销售很大差异消费品的企业，通常都把收益的10％－20％用于广告支出。总体上，广告支出占企业总收益的2％左右,或者在1000亿美元以上。Advertising广告Criticsofadvertisingarguethatfirmsadvertiseinordertomanipulatepeople’stastes.

广告的批评者认为，企业做广告是为了操纵人们的嗜好。Theyalsoarguethatitimpedescompetitionbyimplyingthatproductsaremoredifferentthantheytrulyare.

批评者还认为，广告抑制了竞争。广告努力使消费者相信产品差异大于实际情况。AdvertisingDefendersarguethatadvertisingprovidesinformationtoconsumersTheyalsoarguethatadvertisingincreasescompetitionbyofferingagreatervarietyofproductsandprices.Thewillingnessofafirmtospendadvertisingdollarscanbeasignaltoconsumersaboutthequalityoftheproductbeingoffered.广告广告的辩护者认为，企业用广告向顾客提供信息。辩护者还认为，广告加剧了竞争，为顾客提供了更多的产品和价格。企业愿意用大量的钱来做广告，这本身就向消费者传递了一个所提供产品质量的信息。BrandNames品牌Criticsarguethatbrandnamescauseconsumerstoperceivedifferencesthatdonotreallyexist.

品牌的批评者认为，品牌使消费者感觉到的产品差异大于实际存在的差异。BrandNamesEvidinginformationaboutquality.givingfirmsincentivetomaintainhighquality.品牌经济学家对品牌的辩护是认为品牌是消费者保证他们购买的物品具有高质量的一种有用方法。提供产品质量信息。向企业提供了保持高质量的激励。SummaryAmonopolisticallycompetitivemarketischaracterizedbythreeattributes:manyfirms,differentiatedproducts,andfr