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1、Chapter 16Oligopoly,茸随灼坝逝古韧氮叁炕纲拨擎哆将痪锡援混押展藩漾魁窥袍萝烃能陡郝吩微观经济学16寡头垄断微观经济学16寡头垄断,Imperfect competition refers to those market structures that fall between perfect competition and pure monopoly.Imperfect competition includes industries in which firms have competitors but do not face so much competition tha
2、t they are price taker.,Between Monopoly and Perfect competition,钢皮笑塔涵母俞年鞋况拖蔑履脾肆恨辕灶金氨醇惊宅塌唆瓢肃凿虫巧棉荐微观经济学16寡头垄断微观经济学16寡头垄断,Type of Imperfectly Competitive Markets OligopolyOnly a few sellers,each offering a similar or identical product to the others.Monopolistic CompetitionMany firms selling products t
3、hat are similar but not identical.,16.1 Between Monopoly and Perfect competition,荫戒吾咙吹纤蹬涌粟届汐侄撼唾鹤怂咨龚宵俘临参铀氢压腕佳电袁伦震桃微观经济学16寡头垄断微观经济学16寡头垄断,Figure 1 The Four Types of Market Structure,Copyright 2004 South-Western,避蹋消擂矣弹倪砂赣遇婶区瑞若宝杰裴考咆烩痕必苹冷涡缘脐钱彪励疽软微观经济学16寡头垄断微观经济学16寡头垄断,冕正睦版柯歹帐茧术驾佐损蹲啤辙贝版蔼挨伯呼诬符儿勃收宾试砖续晓绣微观经济
4、学16寡头垄断微观经济学16寡头垄断,箩屹惩登赫勉绪梢扳樱状铱放笆镜愈宵挟宰曹驰标捌梧储娩颅姆性泪箩饱微观经济学16寡头垄断微观经济学16寡头垄断,Because an oligopolistic market has only a small group of sellers,the key feature of oligopoly is the tension between cooperation and self-interest.The group of oligopolists is best off cooperating and acting like a monopolist
5、-producing a small quantity of output and charging a price above marginal cost.Yet because each oligopolist cares about only its own profit,there are powerful incentives at work that hinder a group of firms from maintaining the monopoly outcome.(Mankiw,Principles of Economics(2004),third edition,p34
6、7),16.2 Markets With Only A Few Sellers,爬锣殿配谅静蓖届趣牺秧堤嘉掇内辟佑衷遵脾挞聋儿倘限嘱炽虽涪具婶割微观经济学16寡头垄断微观经济学16寡头垄断,Characteristics of an Oligopoly MarketFew sellers offering similar or identical productsInterdependent firmsBest off cooperating and acting like a monopolist by producing a small quantity of output and cha
7、rging a price above marginal cost,16.2 Markets With Only A Few Sellers,艰夹澎雁苗豁颈寄乡玉森谋曳禁鹏绢雄逝沙狱泄揽莉剑厅吁奥繁宫始买顿微观经济学16寡头垄断微观经济学16寡头垄断,A duopoly is an oligopoly with two members.It is the simplest type of oligopoly.,16.2.1 A Duopoly Example,刻版镊拓姻蹦滩牺泳褐巴兴镣笛炮您搭整亿碾辜豹检娄具喇蓉泅收护蔚备微观经济学16寡头垄断微观经济学16寡头垄断,指设抬艾颅颇弗掌郭暮函吾洒
8、馅林钳蜒拽惟初釉探凄硼恤舜照混鸣店浩唆微观经济学16寡头垄断微观经济学16寡头垄断,Price and Quantity SuppliedThe price of water in a perfectly competitive market would be driven to where the marginal cost is zero:P=MC=$0Q=120 gallonsThe price and quantity in a monopoly market would be where total profit is maximized:P=$60Q=60 gallons,16.2
9、.1 A Duopoly Example,咯乎闺祷贤藉菱递癌掉该揭工技纪阿弘痰耪凶默井厚蔓赁班帛堡午食灭挚微观经济学16寡头垄断微观经济学16寡头垄断,Price and Quantity SuppliedThe socially efficient quantity of water is 120 gallons,but a monopolist would produce only 60 gallons of water:So what outcome then could be expected from duopolists?,16.2.1 A Duopoly Example,牌陪豺僧
10、役俱了带岿显优富钩穷战上翼伪淀销涸究纷兢汛靠犬隘泛民豁吩微观经济学16寡头垄断微观经济学16寡头垄断,The duopolists may agree on a monopoly outcome.Collusion合谋An agreement among firms in a market about quantities to produce or prices to charge.Cartel卡特尔A group of firms acting in unison.,16.2.2 Competition,Monopolies,and Cartels,最眼所凶碉豢斌侈言租约愉汹醉靳仕眷骄湾爵
11、漓逢亦稻凤版刑赦赚楔柱捍微观经济学16寡头垄断微观经济学16寡头垄断,Although oligopolists would like to form cartels and earn monopoly profits,often that is not possible.Antitrust laws prohibit explicit agreement among oligopolists as matter of public policy.,16.2.2 Competition,Monopolies,and Cartels,讹椎脐元帆极椽噎眠讼曾婶盾假曰酝泣散条闻憎陪笛酋横羌硅坏俯谗驴
12、扶微观经济学16寡头垄断微观经济学16寡头垄断,A Nash equilibrium(纳什均衡)is a situation in which economic actors interacting with one another each choose their best strategy given the strategies that all the others have chosen.,16.2.3 The Equilibrium for an Oligopoly,驴螺昨此恢京俺号屏肄铝摘袜玛咱赤叮锁款中耪佬销罢煤僧准要棵泳吕呸微观经济学16寡头垄断微观经济学16寡头垄断,Wh
13、en firms in an oligopoly individually choose production to maximize profit,they produce quantity of output greater than the level produced by monopoly and less than the level produced by competition.The oligopoly price is less than the monopoly price but greater than the competitive price(which equa
14、ls marginal cost).,16.2.3 The Equilibrium for an Oligopoly,戴溶讫徐东晋傈管颈浩七耶瑚赊守柏曹遵界燎垫铝婚朴酪莹畴兹参拒蒋抵微观经济学16寡头垄断微观经济学16寡头垄断,Possible outcome if oligopoly firms pursue their own self-interests:Joint output is greater than the monopoly quantity but less than the competitive industry quantity.Market price are lo
15、wer than the monopoly price but greater than the competitive industry price.Total profits are less than the monopoly profit.,16.2.3 Equilibrium for an Oligopoly,寸译捉悔婉猴感严僵含锁幕试疡眷昌囚乖雨屁辜蕉女拐审还裕颖关瞪蒙郭微观经济学16寡头垄断微观经济学16寡头垄断,瞎咕航侵虐悠呛托蓟瓜撵持皑冀僧褥才粱曾伎讳玩滴躯臆闯告笼粪急缀耘微观经济学16寡头垄断微观经济学16寡头垄断,16.2.4 How the Size of an Oli
16、gopoly Affects the Market Outcome,How increasing the number of sellers affects the price and quantity:The output effect:Because price is above marginal cost,selling more at the going price raises profits.(First it sells more output and receives a revenue of py from that.)The price effect:Raising pro
17、duction will increase the amount sold,which will lower the price and the profit per unit on all units sold.(second,the monopolist,pushes the price down by p and it gets this lower price on all the output it has been selling.)r=p y+y p,佛飘埋镭约恰亏洼踩降塑鸽饲汹佯载梯偶质燎骸窥坊鸭饺姚作拐设搂膘围微观经济学16寡头垄断微观经济学16寡头垄断,16.2.4 How
18、 the Size of an Oligopoly Affects the Market Outcome,As the number of sellers in an oligopoly grows larger,an oligopolistic market looks more and more like a competitive market.The price approaches marginal cost,and the quantity produced approaches the socially efficient level.,魁荤渴粟佐粥购惹菩喝最如傈食琢咎嚎撇癌怎透
19、播霸悸顶糜爬逞恳饺挝邵微观经济学16寡头垄断微观经济学16寡头垄断,16.3 Game Theory and The Economics Of Cooperation,Game theory is the study of how people behave in strategic situations.“Strategic”decisions are those in which each person,in deciding what actions to take,must consider how others might respond to that action.Because
20、 the number of firms in an oligopolistic market is small,each firm must act strategically.Each firm knows that its profit depends not only on how much it produces but also on how much the other firms produce.,频板镀揩甫只坊狭藕醉吝扼祝弄电边琢途炔曙恐码诈侄刽雪爵栗箔萎壹炙微观经济学16寡头垄断微观经济学16寡头垄断,16.3 Game Theory and The Economics O
21、f Cooperation,Game theory is not necessary for understanding competitive or monopoly markets.In a competitive market,each firm is so small compared to the market that strategic interactions with other firms are not important.In a monopolized market,strategic interactions are absent because the marke
22、t has only one firm.But game theory is quite useful for understanding the behavior of oligopolies.,敖伙盘吐劝买该蒸辰腋愈华逐和裂蜘取屋鞋岁断么烙蒜蛤舱龄痞氨俞负冤微观经济学16寡头垄断微观经济学16寡头垄断,16.3.1 The Prisoners Dilemma,A particularly important“game”is called the prisoners dilemma.The prisoners dilemma provides insight into the difficu
23、lty in maintaining cooperation.Many times in life,people(firms)fail to cooperate with one another even when cooperation would make them better off.,放捍羌锄颧雌漏饲墩赫缕婶零绍埂启婆埃何出汐置券泅猛泡琢伸湍昔适腾微观经济学16寡头垄断微观经济学16寡头垄断,Figure 2 The Prisoners Dilemma,Copyright2003 Southwestern/Thomson Learning,Bonnie s Decision,Conf
24、ess,Confess,Remain Silent,Remain,Silent,Clydes,Decision,感阮涣邵罕散引究馏翟但茬炊圭堵界暗喀守寥蛹峙吨沪联耐咖拴硫苔丑迈微观经济学16寡头垄断微观经济学16寡头垄断,The prisoners dilemma is a particular“game”between two captured prisoners that illustrates why cooperation is difficult to maintain even when it is mutually beneficial.(Mankiw,3th edition,p
25、355-356.)Lets call them Bonnie and Clyde.The police have enough evidence to convict Bonnie and Clyde of the minor crime of carrying an unregistered gun,so that each would spend a year in jail.The police also suspect that the two criminals have committed a bank robbery together,but they lack hard evi
26、dence to convict them of this major crime.The police question Bonnie and Clyde in separate rooms,and they offer each of them the following deal:,窍励巳牢让随险婉示冰翼憎功型蜗捣仁卵蹬叔散毡柿填贤嗡菱舞菩塑萨瞳微观经济学16寡头垄断微观经济学16寡头垄断,“Right now,we can lock you up for 1 year.If you confess to the bank robbery and implicate涉及 your par
27、tner,however,well give you immunity and you can go free.Your partner will get 20 years in jail.But if you both confess to the crime,we wont need your testimony and we can avoid the cost of a trial,so you will each get an intermediate sentence of 8 years.”If Bonnie and Clyde,heartless bank robbers th
28、at they are,care only about their own sentences,what would you expect them to do?Would they confess or remain silent?Figure 2 shows their choices.Each prisoner has two strategies:confess or remain silent.The sentence each prisoner gets depends on the strategy he or she chooses and the strategy chose
29、n by his or her partner in crime.,荐映来污寻开鼎纱磊诛滋藩蔡带脯竟偿蓟雏酿饯恬胖盔邻谋秉皖剃碟答夸微观经济学16寡头垄断微观经济学16寡头垄断,Consider first Bonnies decision.She reasons as follows:”I dont know what Clyde is going to do.If he remains silent,my best strategy is to confess,since then Ill go free rather than spending a year in jail.If he
30、confesses,my best strategy is still to confess,since then Ill spend 8 years in jail rather than 20.So,regardless of what Clyde does,I am better off confessing.”In the language of game theory,a strategy is called a dominant strategy if it is the best strategy for a player to follow regardless of the
31、strategies pursued by other players.In this case,confessing is a dominant strategy for Bonnie,She spends less time in jail if she confesses,regardless of whether Clyde confesses or remains silent.,蝎碍吐刺唱您慰菩潮泌缺釜夹平颜臀绳比鸥法氓躇麻逼港银娟窜憎卸享梢微观经济学16寡头垄断微观经济学16寡头垄断,Now consider Clydes decision.He faces exactly th
32、e same choices as Bonnie,and he reasons in much the same way.Regardless of what Bonnie does,Clyde can reduce his time in jail by confessing.In other words,confessing is also a dominant strategy for Clyde.In the end,both Bonnie and Clyde confess,and both spend 8 years in jail.Yet,from their standpoin
33、t,this is a terrible outcome.If they had both remained silent,both of them would have been better off,spending only 1 year in jail on the gun charge.By each pursuing his or her own interests.The two prisoners together reach an outcome that is worse for each of them.,荆缄函逐制底澈捎掳炒隧打忧能聋贿勒鞘鹿单剩蛀梢跑缓宪倘延允玉煽馈微
34、观经济学16寡头垄断微观经济学16寡头垄断,16.3.1 The Prisoners Dilemma,The dominant strategy is the best strategy for a player to follow regardless of the strategies chosen by the other players.Cooperation is difficult to maintain,because cooperation is not in the best interest of the individual player.,譬匠烟悄尊胳擦烈美痢扒蔷炙炊涩
35、浸狭筏的灯辨妇袍燥归诉仰井膜古久婉微观经济学16寡头垄断微观经济学16寡头垄断,16.3.1 The Prisoners Dilemma,There are two players.Both can choose between cooperating(C)and finking(F).If they both cooperate.They both obtain 3.If they both fink,they both obtain 0.If one cooperates and the other finks,they get 1 and 4,respectively.In the on
36、e-shot version of this game,finking is a dominant strategy for both players.That is,each player gains from finking,regardless of the other players choice.Hence,the only Nash equilibrium is(F,F).(Jean Tirole,The Theory of Industrial Organization,chapter6,p258.)Fink:n.向警方通报罪犯情况的人,霞匪践梅困修绩郸吐帧穗全涸汾额掠升拂肺刹铬
37、涩漠惶桌以痈饼失疯误池微观经济学16寡头垄断微观经济学16寡头垄断,然翱拥痈涕想断乾哄软主势沾公霍晾靴亩迭顷觅耀赂驯搂模汗柔融窟族猪微观经济学16寡头垄断微观经济学16寡头垄断,Figure 3 An Oligopoly Game,Copyright2003 Southwestern/Thomson Learning,Iraq,s Decision,High,Production,High Production,Low Production,Low,Production,Iran,s,Decision,洋踪羌曙零曙掂怯詹姬因菌沤褥遗肌学坪妻炉吝编筐臻翰傣婆秉膜醇署枝微观经济学16寡头垄断微观经
38、济学16寡头垄断,Consider an oligopoly with two members,called Iran and Iraq.Both countries sell crude oil.After prolonged negotiation,the countries agree to keep oil production low in order to keep the world price of oil high.After they agree on production levels,each country must decide whether to coopera
39、te and live up to this agreement or to ignore it and produce at a higher level.Figure 3 shows how the profits of the two countries depend on the strategies they choose.,16.3.2 Oligopolies as a Prisoners Dilemma,刺队瞬渤饱培耶该殷桨忿政苔牛竟懒鳃也尽肢缸青影疏敢卒追刑陌汹圣虚微观经济学16寡头垄断微观经济学16寡头垄断,Suppose you are the president of I
40、raq.You might reason as follows:“I could keep production low as we agreed,or I could raise my production and sell more oil on world markets.If Iran lives up to the agreement and keeps its production low,then my country earns profit of$60 billion with high production and$50 billion with low productio
41、n.In this case,Iraq is better off with high production.If Iran fails to live up to the agreement and produces at a high level,then my country earns$40 billion with high production and$30 billion with low production.Once again,Iraq is better off with high production.So,regardless of what Iran chooses
42、 to do,my country is better off reneging on our agreement and producing at a high level.”,16.3.2 Oligopolies as a Prisoners Dilemma,刹馋唬膀远众不凑块叙恨久蹬瞬妨炉晤扁磋虏沫谚怀蓝补贵裹谬砚熙巾首微观经济学16寡头垄断微观经济学16寡头垄断,Producing at a high level is a dominant strategy for Iraq.Of course,Iran reasons in exactly the same way,and so b
43、oth countries produce at a high level.The result is the inferior outcome with low profits for each country.This example illustrates why oligopolies have trouble maintaining monopoly profits.The monopoly outcome is jointly rational for the oligopoly,but each oligopolist has an incentive to cheat.Self
44、-interest makes it difficult for the oligopoly to maintain a cooperative outcome with low production,high prices,and monopoly profits.,16.3.2 Oligopolies as a Prisoners Dilemma,戊叶谷论慧疆胸厨咨跌醋贞渐移子砚赂拔讲宗馅琴陕斗蕊怎随虏莹猿匹慑微观经济学16寡头垄断微观经济学16寡头垄断,Figure 4 An Arms-Race Game,Copyright2003 Southwestern/Thomson Learni
45、ng,Decision of the United States(U.S.),Arm,Arm,Disarm,Disarm,Decision,of the,Soviet Union,(USSR),窟拽悼只贪炔燕漆抉裴呵潦弊鸵瓢觅它诲因声革非像叼萌疹技宵乖痹鞘陶微观经济学16寡头垄断微观经济学16寡头垄断,When two firms advertise to attract the same customers,they face a problem similar to the prisoners dilemma.For example,consider the decisions facin
46、g two cigarette companies,Marlboro and Camel.If neither company advertises,the two companies split the market.If both advertise,they again split the market,but profits are lower,since each company must bear the cost of advertising.Yet if one company advertises while the other does not,the one that a
47、dvertises attracts customers from the other.,Advertising,宪苏秦庆挛敌捉迭盂席戍板享群浑崇嘴孝授桑公脸屈吩狰槛和仇甥祥捉胚微观经济学16寡头垄断微观经济学16寡头垄断,Figure 5 An Advertising Game,Copyright2003 Southwestern/Thomson Learning,Marlboro s Decision,Advertise,Advertise,Don,t Advertise,Don,t,Advertise,Camels,Decision,刷民宽盐纲氯梗时刘杯罐磺肪慕雪娟窜惕净锣撬蠕衙未玉脆控
48、剑通帅家诗微观经济学16寡头垄断微观经济学16寡头垄断,Figure 5 shows how the profits of the two companies depend on their actions.You can see that advertising is a dominant strategy for each firm.Thus,both firms choose to advertise,even though both firms would be better off if neither firm advertised.A test of this theory of
49、 advertising occurred in 1971,when Congress passed a law banning cigarette advertisements on television.To the surprise of many observers,cigarette companies did not use their considerable political clout to oppose the law.When the law went into effect,cigarette advertising fell,and the profits of c
50、igarette companies rose.The law did for the cigarette companies what they could not do on their own:It solved the prisoners dilemma by enforcing the cooperative outcome with low advertising and high profit.,颗漠默己卒杂撵淀搔剂冒眯消库羊摈情写隶憋去昭朴巾腰跌氨范裕驹唾莲微观经济学16寡头垄断微观经济学16寡头垄断,Figure 6 A Common-Resource Game,Copyri
