完全竞争市场上的厂商均衡.pptx

完全竞争市场上的厂商均衡完全竞争市场上的厂商均衡 7.2 The Equilibrium of the Firm under Perfect Competition教学目标教学目标Objectives：了解完全竞争的市场条件掌握完全竞争市场的需求曲线和收益曲线掌握完全竞争市场的短期均衡条件掌握完全竞争市场的长期均衡条件知识点知识点Knowledge：完全竞争的市场条件、完全竞争市场的需求曲线和收益曲线完全竞争市场的短期均衡和长期均衡条件技能点技能点Skills：绘制完全竞争市场均衡图pricetakeradvertisingmarketopportunitiesidealtypeadvantagesshortcomingsgovernmentNormalprofitSupernormalprofitleast-costeconomicprofitabnormalprofithomogeneousproducteconomiesofscaleindustry专业词汇专业词汇Professional terms一、完全竞争的含义与条件一、完全竞争的含义与条件 AssumptionslFirmsarepricetaker.lThereiscompletefreedomofentryintotheindustryfornewfirms.l All firms produce an identical product.The product ishomogeneous,sothereisnobrandingandadvertising.lProducersandconsumershaveperfectknowledgeofthemarket.Thatis,producersarefullyawareofprices,costsandmarketopportunities.Consumersarefullyawareoftheprice,quantityandavailabilityoftheproduct.Nevertheless,despitethelackofreal-worldcases,the model of perfect competition plays a veryimportantroleineconomicanalysisandpolicy.Itsmajorrelevanceisasanidealtype.Manyonthepoliticalrightarguethatperfectcompetitionbringsanumberofimportantadvantages.Themodelcanthusbeusedasastandardagainstwhichtojudgetheshortcomingsofrealworldindustries.Itcanhelp government to formulate policies towardsindustry.一、完全竞争的含义与条件一、完全竞争的含义与条件 实现完全竞争的条件包括：实现完全竞争的条件包括：第一，市场上有许多生产者与消费者，每一个生产者的销售量与消费者的购买量只占市场极小的份额。第二，市场上的产品是同质的，即不存在产品差别。第三，资源完全自由流动。第四，市场信息是畅通的。一、完全竞争的含义与条件一、完全竞争的含义与条件 TheshortrunandthelongrunlThe short run under perfect competition The periodduringwhichthereistoolittletimefornewfirmstoentertheindustry.lThe long run under perfect competition Theperiodoftimethatislongenoughfornewfirmstoentertheindustry.Normal profitTheopportunitycostofbeinginbusiness:theprofitthatcouldhavebeenearnedinthenextbestalternativebusiness.Itiscountedasacostofproduction.Supernormal profit(also known as pure profit,economic profit,abnormal profit or simply profit)Theexcessoftotalprofitabovenormalprofit.二、完全竞争市场上的需求和收益曲线二、完全竞争市场上的需求和收益曲线 0 Q0 Q0 Q1 Q2 QTR完全竞争市场上的需求曲线与收益曲线完全竞争市场上的需求曲线与收益曲线PPP0P0DSEd(MR=AR=P)(a)(c)(b)TR2TR1TR Q三、完全竞争市场上的短期均衡三、完全竞争市场上的短期均衡 完全竞争市场均衡图完全竞争市场均衡图0 Q0 QE E Q QP PE Ed d（MR=AR=PMR=AR=P）P PE ESMCSMC三、完全竞争市场上的短期均衡三、完全竞争市场上的短期均衡 PE ESMCSMCSACSACPEd d（MR=AR=PMR=AR=P）0 Q0 QE E Q Q完全竞争市场厂商盈亏平衡图完全竞争市场厂商盈亏平衡图厂商获得正常利润(normalprofit)三、完全竞争市场上的短期均衡三、完全竞争市场上的短期均衡 厂商获得超额利润(supernormalprofit)F Fd d（MR=AR=PMR=AR=P）E ESMCSMCSACSACP PP PE EP PF F0 Q0 QE E Q Q完全竞争厂商取得超额利润分析图完全竞争厂商取得超额利润分析图三、完全竞争市场上的短期均衡三、完全竞争市场上的短期均衡 厂商遭受亏损SMCSMCSACSACd d（MR=AR=PMR=AR=P）F FEPPFPE0 Q0 QE E Q Q完全竞争亏损厂商均衡分析图完全竞争亏损厂商均衡分析图三、完全竞争市场上的短期均衡三、完全竞争市场上的短期均衡 ACBSMCSACAVCPPAPBPCd(AR=MR=PB)亏损企业经营规模调整分析图亏损企业经营规模调整分析图四、完全竞争市场上的长期均衡四、完全竞争市场上的长期均衡Revenue and cost0QuantityP=AR=MRACMCPQNORMAL PROFIT五、对完全竞争市场的评论五、对完全竞争市场的评论 Inmanyindustries,firmsmayhavetobequitelargeifthey are to experience the full potential economies ofscale.Butperfectcompetitionrequirestheretobemanyfirms.Firms must therefore be small in most foreconomiesofscale.Onceafirmexpandssufficientlytoachieveeconomiesofscale,itwillusuallygainmarketpower.Itwillbeabletoundercutthepricesofsmallerfirms,whichwillthusbe driven out of business.Perfect competition isdestroyed.Perfect competition could only exist in any industry,therefore,iftherewereno(orvirtuallyno)economiesofscale.Perfect competition and the public interestThere are a number of features of perfect competitionwhich,itcouldbeargued,benefitsociety:l Price equals marginal cost,which has importantimplications for the allocation of resources betweenalternativeproducts.lIfafirmbecomeslessefficientthanotherfirms,itwillmakelessthannormalprofitsandbedrivenoutofbusiness.Ifitismoreefficient,itwillearnsupernormalprofits.Thusthecompetitionbetweenfirmswillactasaspurtoefficiency.lSimilarly,thedesireforsupernormalprofit,andthedesiretoavoidloss,willencouragethedevelopmentofnewtechnology.Perfect competition and the public interestlThereis no pointinadvertisingunder perfectcompetition,since all firms produce a homogeneous product.This and theprevioustwofactorswillleadtolowACcurves,andhencetoaneconomicaluseofthenationsscarceresources.lForanygiventechnology,thefirm,inthelongrun,willproduceattheleast-costoutput.lTheconsumergainsfromlowprices,sincenotonlyarecostskept low,but also there are no long-run supernormal profits tothesecosts.lIfconsumertasteschange,theresultingpricechange,theresultingpricechangewillleadfirmstorespond(purelyoutofself-interest).Anincreasedconsumerdemandwillcallforthextrasupplywithonlyashort-runincreaseinprofit.五、对完全竞争市场的评论五、对完全竞争市场的评论 第一，社会供给与需求相等，使资源得到最优配置，生产者的生产不会有不足或过剩，消费者的需求也得到了充分满足。第二，在长期均衡时所达到的平均成本处于最低点，表明可以通过完全竞争与资源的自由流动，使生产要素的效率得到最有效的发挥。第三，平均成本最低决定了产品的价格也是最低的，这对消费者是有利的。益处：益处：五、对完全竞争市场的评论五、对完全竞争市场的评论 第一，各厂商的平均成本最低并不一定是社会成本最低。第二，产品无差别，这样，消费者的多种需求无法得到满足。第三，完全竞争市场上生产者的规模都很小，这样，他们没有能力去实现重大的科学技术突破，从而不利于科学技术发展和科技创新。第四，在实际经济生活中，完全竞争的情况是很少的，而且，一般来说，竞争也必然引起垄断。弊端：弊端：