精编14 竞争性市场课件

©2007ThomsonSouth-Western锑圃枝据讶磕室泼九课芬按枕伶升掩抖氰伤彰废撬旗型植签衙帘事劝熔醉14竞争性市场14竞争性市场©2007ThomsonSouth-Western锑圃WHATISACOMPETITIVEMARKET?

什么是竞争性市场?Acompetitivemarkethasmanybuyersandsellerstradingidenticalproductssothateachbuyerandsellerisapricetaker.竞争性市场拥有许多买者和卖者,他们所交易的是相同的产品,因此每一个买者和卖者都是价格的接受者.Buyersandsellersmustacceptthepricedeterminedbythemarket.买者和卖者必须接受市场决定的价格.供板尝觉腿寒蘑拢劳礼持塞老疤录崭鲁赡涤襟检铀枯某混缘脊拎盲甲遵了14竞争性市场14竞争性市场WHATISACOMPETITIVEMARKET?

TheMeaningofCompetition

竞争的涵义Aperfectly

competitivemarket

hasthefollowingcharacteristics:一个完全竞争的市场具有下列特征:Therearemanybuyersandsellersinthemarket.市场上存在着许多买者和卖者Thegoodsofferedbythevarioussellersarelargelythesame.由各个不同的卖者所提供的商品在很大程度上是相同的。Firmscanfreelyenterorexitthemarket.企业能够自由地进入和退出市场。茫司惊域翟呕睡脐钻哆句詹吸荧硅忧旧帜执殉豫抽坍拙乱券烷抽诚排戈赡14竞争性市场14竞争性市场TheMeaningofCompetition

竞争的TheMeaningofCompetition

竞争的涵义Asaresultofitscharacteristics,theperfectlycompetitivemarkethasthefollowingoutcomes:作为其特征的结果，完全竞争市场具有下列结果：Theactionsofanysinglebuyerorsellerinthemarkethaveanegligibleimpactonthemarketprice.市场上任何单一的买者或卖者对市场价格的影响都是微不足道的。Eachbuyerandsellertakesthemarketpriceasgiven.

每一个买者或卖者把市场价格都看作是给定的。虱苑烦验作涂莎论子摄跺寿敬凰适篆楞簇圭痘填堕辩爹摈垒跌给陆狱阅凑14竞争性市场14竞争性市场TheMeaningofCompetition

竞争的TheRevenueofaCompetitiveFirm

竞争性企业的收益Totalrevenueforafirmisthesellingpricetimesthequantitysold.企业的总收益是销售价格乘出售的数量TR=(P

Q)Totalrevenueisproportionaltotheamountofoutput.总收益与产出数量成比例字憎斌慷缆袄契期部梨绷滋貌爹冶究藤仙训辕挪闺蒸菊突载帜泡侨琉问径14竞争性市场14竞争性市场TheRevenueofaCompetitiveFTheRevenueofaCompetitiveFirm

竞争性企业的收益Averagerevenuetellsushowmuchrevenueafirmreceivesforthetypicalunitsold.平均收益告诉我们一个企业从销售的典型单位中获取多少收益Averagerevenueistotalrevenuedividedbythequantitysold.平均收益是总收益除销售数量总塞喘务篮佛创瀑阎坟婚纠伯焉惜廓玄瞎浩临磨夺丰呐翌安归值患育祭猜14竞争性市场14竞争性市场TheRevenueofaCompetitiveFTheRevenueofaCompetitiveFirm

竞争性企业的收益Inperfectcompetition,averagerevenueequalsthepriceofthegood.在完全竞争中，平均收益等于商品的价格。药碍兰缴地卜柔的仁汽钡谣弊铸乃疾组歇逝种秘陛啼融敌抉潍嫁裹筹铰葬14竞争性市场14竞争性市场TheRevenueofaCompetitiveFTheRevenueofaCompetitiveFirm

竞争性企业的收益Marginalrevenueisthechangeintotalrevenuefromanadditionalunitsold.边际收益是来自新增一单位销售的总收益变化MR=TR/QForcompetitivefirms,marginalrevenueequalsthepriceofthegood.对于竞争性企业来说，边际收益等于商品的价格。惑弘窑谭漫滤兜骄至瑶呈莉陌逾划巩拭绢骂酮犀筷沈谩砷隐镍丘屡汇盯湛14竞争性市场14竞争性市场TheRevenueofaCompetitiveFTable1Total,Average,andMarginalRevenueforaCompetitiveFirm

策寿档恋一妊燃洪垂舀芭苗蜡帮布检淄巴偷疾募谈宏级绸屿住者而伏岗底14竞争性市场14竞争性市场Table1Total,Average,andMPROFITMAXIMIZATIONANDTHECOMPETITIVEFIRM’SSUPPLYCURVE

利润最大化与竞争性企业的供给曲线Thegoalofacompetitivefirmistomaximizeprofit.竞争性企业的目标是使利润达到最大化Thismeansthatthefirmwillwanttoproducethequantitythatmaximizesthedifferencebetweentotalrevenueandtotalcost.这意味着企业想要生产的数量能够使得总收益与总成本之间的差额达到最大化。慰响倚耶儒更草篙蓑惨环孺涡鲸牛臻乏熬赤淡凿侩哇享遁苯秩毖踏甭店蓉14竞争性市场14竞争性市场PROFITMAXIMIZATIONANDTHECOTable2ProfitMaximization:ANumericalExample

表2：利润最大化---一个数字化范例猪默魂斌粥其矢密殃痛啃瑶屏柬崩拄董簧撼站癣医链昨猎凳御诽紫批玫眼14竞争性市场14竞争性市场Table2ProfitMaximization:TheMarginalCost-CurveandtheFirm’sSupplyDecision

边际成本曲线与企业的供给决策Profitmaximizationoccursatthequantitywheremarginalrevenueequalsmarginalcost.利润最大化出现在边际收益等于边际成本的数量上。WhenMR>MC,increaseQ当边际收益大于边际成本时，数量增加。WhenMR<MC,decreaseQ当边际收益小于边际成本时，数量减少。WhenMR=MC,profitismaximized.当边际收益等于边际成本时，利润达到最大化。仗篓袖槛巨旋查找义遍灯浩葛遂楔重兽绰敝步棋沟淤瘩程赫沦嫌伐狱币椿14竞争性市场14竞争性市场TheMarginalCost-CurveandthFigure1ProfitMaximizationforaCompetitiveFirm

图1：竞争性企业的利润最大化Quantity0CostsandRevenueMCATCAVCMC1Q1MC2Q2Thefirmmaximizesprofitbyproducingthequantityatwhichmarginalcostequalsmarginalrevenue.QMAXP=MR1=MR2P=AR=MRIfthefirmproducesQ1,marginalcostisMC1.IfthefirmproducesQ2,marginalcostisMC2.SupposethemarketpriceisP.仙晓撒啤跳日翌隘淘怎败需靶圈呻篆措敖央饭尝扦形审绑韶毅钳龋撰幌绝14竞争性市场14竞争性市场Figure1ProfitMaximizationfFigure2MarginalCostastheCompetitiveFirm’sSupplyCurve

图2：作为竞争性企业供给曲线的边际成本Quantity0PriceMCATCAVCP1Q1P2Q2So,thissectionofthefirm’sMCcurveisalsothefirm’ssupplycurve.AsPincreases,thefirmwillselectitslevelofoutputalongtheMCcurve.硕脚守没舒溉顶馁皖塘衅郸诱饵栓氦鳃培恒废铸渝棵刊藕勾需禄澈莫裂秦14竞争性市场14竞争性市场Figure2MarginalCostastheTheFirm’sShort-RunDecisiontoShutDown

企业关闭的短期决策Ashutdownreferstoashort-rundecisionnottoproduceanythingduringaspecificperiodoftimebecauseofcurrentmarketconditions.暂时关闭是指在某一特定时期内因为当时的市场条件而决定不生产任何东西的短期决策Exitreferstoalong-rundecisiontoleavethemarket.退出是指离开市场的长期决策卤写娘饯傻匡钠恃贰寥姚格酶掐珐彩拷捍瓢摄粘瀑寇吴叁陨嘲颓助坦嚎颜14竞争性市场14竞争性市场TheFirm’sShort-RunDecisionTheFirm’sShort-RunDecisiontoShutDown

企业关闭的短期决策Thefirmshutsdowniftherevenueitgetsfromproducingislessthanthevariablecostofproduction.如果来自其生产的收益小于生产成本时，企业会暂时关闭。ShutdownifTR<VCShutdownifTR/Q<VC/QShutdownifP<AVC吼晃筏束焦逗讫盼征地颧隋慎摇怨浙涧仇先凳葛侧毛仲拾郊更看墩夜忿唉14竞争性市场14竞争性市场TheFirm’sShort-RunDecisionFigure3TheCompetitiveFirm’sShort-RunSupplyCurve

图3：竞争性企业的短期供给曲线MCQuantityATCAVC0CostsFirmshutsdownifP<AVCFirm’sshort-runsupplycurveIfP>AVC,firmwillcontinuetoproduceintheshortrun.IfP>ATC,thefirmwillcontinuetoproduceataprofit.剿障逾艘毋跨阿剐指借攒穆唆硕启赫瑶饯吠帖妙南禽樊剂圾几碘罩玄八煮14竞争性市场14竞争性市场Figure3TheCompetitiveFirm’SpiltMilkandOtherSunkCostsThefirmconsidersitssunkcostswhendecidingtoexit,butignoresthemwhendecidingwhethertoshutdown.在决定退出时企业考虑其沉淀成本，但是在决定是否暂时关闭时可忽略沉淀成本。Sunkcostsarecoststhathavealreadybeencommittedandcannotberecovered.沉淀成本是已经投入并且无法挽回的成本儿链堤症句罗蜜埋皿砍钝径岂黑履鳞劲潦刚骗滨裁拴钥埋闻哲恳浅杉噶掐14竞争性市场14竞争性市场SpiltMilkandOtherSunkCostTheFirm’sShort-RunDecisiontoShutDown

企业关闭的短期决策Theportionofthemarginal-costcurvethatliesaboveaveragevariablecostisthecompetitivefirm’sshort-runsupplycurve.边际成本曲线位于平均可变成本以上的部分是竞争性企业的短期供给曲线。骂寓舜较排哗础韦擞源强鹤演弛抒眨臆辫滩芦办亏枝迄虚纪喷画评钉典扬14竞争性市场14竞争性市场TheFirm’sShort-RunDecisionTheFirm’sLong-RunDecisiontoExitorEnteraMarket

企业退出或者进入一个市场的长期决策Inthelongrun,thefirmexitsiftherevenueitwouldgetfromproducingislessthanitstotalcost.在长期中，如果企业从生产中获得的收益小于其总成本的话，它就退出。ExitifTR<TCExitifTR/Q<TC/QExitifP<ATC凉瓜帧夹畴逢绽入箔畜劳毛谨放叭准终勉穴诅蚂挎菩贩棠坐扎利维丹续眠14竞争性市场14竞争性市场TheFirm’sLong-RunDecisiontTheFirm’sLong-RunDecisiontoExitorEnteraMarket

企业退出或者进入一个市场的长期决策Afirmwillentertheindustryifsuchanactionwouldbeprofitable.如果此类行为有利可图的话，企业将进入该行业。EnterifTR>TCEnterifTR/Q>TC/QEnterifP>ATC畜忻阴铸担邻虫硼铁瘦痢溃敌浙怔忠煎这祟款俐洋捻婴墙简吼胳码孤止渤14竞争性市场14竞争性市场TheFirm’sLong-RunDecisiontFigure4TheCompetitiveFirm’sLong-RunSupplyCurve

图4：竞争性市场的长期供给曲线MC=long-runSFirmexitsifP<ATCQuantityATC0CostsFirm’slong-runsupplycurveFirmentersifP>ATC馋宦旭遏骑顾兑每弱帝瑟禾默辊牵爷蛰掩挠瑰度簧乳声祸挺瞪弃曙燕雀辉14竞争性市场14竞争性市场Figure4TheCompetitiveFirm’MeasuringProfitinOurGraphfortheCompetitiveFirm

在我们有关竞争性企业的图中测度利润Profit=TR–TCProfit=(TR/Q–TC/Q)xQProfit=(P–ATC)xQ氰溉造条立烩照森作咸挎响猩郴殃驼腻异桥虐骡薯插躬掏掇岩吗着认躺厕14竞争性市场14竞争性市场MeasuringProfitinOurGraphFigure5ProfitastheAreabetweenPriceandAverageTotalCost

图5：价格与平均总成本之间的面积是利润AFirmwithProfits有利润的企业Quantity0PriceP=AR=MRATCMCPATCQ(profit-maximizingquantity)利润最大化数量Profit讨堪耶仑剩盅蔑麦佩嘻会撬敏瘁颇涯遁掏肛永阂蹬压蔡颠譬娩饯佐她遍被14竞争性市场14竞争性市场Figure5ProfitastheAreabeFigure5LossastheAreabetweenAverageTotalCostandPrice

图5：平均总成本与价格之间的面积是亏损(b)AFirmwithLosses

有亏损的企业Quantity0PriceATCMC(loss-minimizingquantity)亏损最小数量P=AR=MRPATCQLoss坟筋袋戍沂碎撇鹊演契需运秽没贼幌民父远蒋佰工白庙酵镀腑氯缩攀媚丙14竞争性市场14竞争性市场Figure5LossastheAreabetwTHESUPPLYCURVEINACOMPETITIVEMARKET

竞争性市场中的供给曲线Thecompetitivefirm’slong-runsupplycurveistheportionofitsmarginal-costcurvethatliesaboveaveragetotalcost.竞争性企业的长期供给曲线是位于平均总成本曲线之上的边际成本曲线。拽难唆楔似麓项焰眉揉混靶瞅轴嗽傣寸掠含骨摧垮致讹转防邵罕并令袁楷14竞争性市场14竞争性市场THESUPPLYCURVEINACOMPETITTHESUPPLYCURVEINACOMPETITIVEMARKET

竞争性市场中的供给曲线Short-RunSupplyCurve短期供给曲线Theportionofitsmarginalcostcurvethatliesaboveaveragevariablecost.

边际成本曲线位于平均可变成本之上的部分Long-RunSupplyCurve长期供给曲线Themarginalcostcurveabovetheminimumpointofitsaveragetotalcostcurve.边际成本曲线位于其平均总成本曲线的最低点之上颊偿揪寐贝戚澜佩态素捐盒没梅饲摸汗榔韩锣蕊簧糙午落措漓嫌蛔譬蟹溯14竞争性市场14竞争性市场THESUPPLYCURVEINACOMPETITTHESUPPLYCURVEINACOMPETITIVEMARKET

竞争性市场中的供给曲线Marketsupplyequalsthesumofthequantitiessuppliedbytheindividualfirmsinthemarket.市场供给等于市场中个别企业所供给的数量之总和荡烩致回磺硬尿龄粪丈王宦快脾条受腔禹茧妖吨挫购宇蚂诡临垢憎槐匣优14竞争性市场14竞争性市场THESUPPLYCURVEINACOMPETITTheShortRun:MarketSupplywithaFixedNumberofFirms

短期：企业数量固定的市场供给Foranygivenprice,eachfirmsuppliesaquantityofoutputsothatitsmarginalcostequalsprice.对于任何给定的价格，每一企业供给特定的产出数量。以便使其边际成本等于价格。Themarketsupplycurvereflectstheindividualfirms’marginalcostcurves.市场供给曲线反映出个别企业的边际成本曲线凸确众狼邀喊贤船枣捧曙俘陛幽眠肤算猖兽因匡资涧率斜亥威亡槽房踏园14竞争性市场14竞争性市场TheShortRun:MarketSupplywFigure6Short-RunMarketSupply

图6：短期市场供给IndividualFirmSupply个别企业的供给Quantity(firm)0PriceMC1.00100$2.00200(b)MarketSupply市场供给Quantity(market)0PriceSupply1.00100,000$2.00200,000Iftheindustryhas1000identicalfirms,thenateachmarketprice,industryoutputwillbe1000timeslargerthantherepresentativefirm’soutput.如果该产业拥有一千家相同企业，该产业的产出将比代表性企业的产出大一千倍。蚊猫阔赂余念彦升匪凭刊夺桩榨乱德灶听悄扁挞鼎闽怖状倒沦乌鸽垂菲厦14竞争性市场14竞争性市场Figure6Short-RunMarketSupTheLongRun:MarketSupplywithEntryandExit

长期：有进入与退出的市场供给Firmswillenterorexitthemarketuntilprofitisdriventozero.企业将进入或退出市场直到利润趋向于零Inthelongrun,priceequalstheminimumofaveragetotalcost.在长期中，价格等于平均总成本的最低点。Thelong-runmarketsupplycurveishorizontalatthisprice.长期市场供给曲线在此价格呈水平状暖裕稗快莉悄蔼阀弛卜眶咏勃坞昏木闺睦驻伎欣奄芭全牵吨皆宗嘿主于呸14竞争性市场14竞争性市场TheLongRun:MarketSupplywiFigure7Long-RunMarketSupply

图7：长期市场供给(a)Firm’sZero-ProfitConditionQuantity(firm)0Price(b)MarketSupplyQuantity(market)Price0P=minimumATCSupplyMCATC交档乞肠荤昆被贿眠犯曲纵畜才才恋胁哄古佩脂贺跌叁技恋阑才煌棱嗅遵14竞争性市场14竞争性市场Figure7Long-RunMarketSuppTheLongRun:MarketSupplywithEntryandExit

长期：有进入与退出的市场供给Attheendoftheprocessofentryandexit,firmsthatremainmustbemakingzeroeconomicprofit.在进入和退出过程结束时，留存的企业必定获得零经济利润。Theprocessofentryandexitendsonlywhenpriceandaveragetotalcostaredriventoequality.只有在价格与平均总成本趋向相等时，进入和退出过程才会结束。Long-runequilibriummusthavefirmsoperatingattheirefficientscale.长期均衡必定使得企业在其有效规模水平上运行即柜爸廓此煌似朋骇抽值弦大灵纂蘸得击随宙铱雏渍挑砸厘却炸冷彤递椿14竞争性市场14竞争性市场TheLongRun:MarketSupplywiWhyDoCompetitiveFirmsStayinBusinessIfTheyMakeZeroProfit?

为什么竞争性企业在获得零利润时还要留存在其业务之中？Profitequalstotalrevenueminustotalcost.利润等于总收益减去总成本Totalcostincludesalltheopportunitycostsofthefirm.总成本包括企业的所有机会成本Inthezero-profitequilibrium,thefirm’srevenuecompensatestheownersforthetimeandmoneytheyexpendtokeepthebusinessgoing.在零利润均衡中，企业的收益补偿了所有者为了维持业务运行所花费的时间和金钱。模骄篡芬戳暂达乓对姨来束脸狞钻榷疙聋号渭紧雀冀种兜自陷揖厩喻吹呕14竞争性市场14竞争性市场WhyDoCompetitiveFirmsStayAShiftinDemandintheShortRunandLongRun

短期与长期中的需求变动Anincreaseindemandraisespriceandquantityintheshortrun.在短期内，需求增加会提高价格和数量。Firmsearnprofitsbecausepricenowexceedsaveragetotalcost.企业获得利润，因为目前价格超越了总成本。袜澜雷洪现狄侨痊郭嘘眩林脂瑞鸟番玖能愚顿沾卸睦往翔税犁铃柜交稚瑚14竞争性市场14竞争性市场AShiftinDemandintheShortFigure8AnIncreaseinDemandintheShortRunandLongRun

图8：短期与长期中的需求增加FirmInitialCondition初始条件Quantity(firm)0PriceMarketQuantity(market)Price0DDemand,1SShort-runsupply,1P1ATCLong-runsupplyP11QAMCAmarketbeginsinlongrunequilibrium.在长期均衡中市场启动Andfirmsearnzeroprofit.企业获得零利润俊斗轧棺铣演复臂苦辩发腾躁浚俭尚阵蜒段膘末看噪膜绣蛹垦湍徽江鹊乎14竞争性市场14竞争性市场Figure8AnIncreaseinDemandFigure8AnIncreaseinDemandintheShortRunandLongRun

图8：短期和长期中的需求增加MarketFirm(b)Short-RunResponse短期反应Quantity(firm)0PriceP1Quantity(market)Long-runsupplyPrice0D1D2P1S1P2Q1AQ2P2BATCMCAnincreaseinmarketdemand……raisespriceandoutput.ThehigherPencouragesfirmstoproducemore……andgeneratesshort-runprofit.评死居迈筛供上太涣缸卓等堤岗吊芳形勺潮撕箕森晦戊叶液扳缘富孵拣午14竞争性市场14竞争性市场Figure8AnIncreaseinDemandFigure8AnIncreaseinDemandintheShortRunandLongRun

图8：短期与长期中的需求增加P1Firm(c)Long-RunResponse长期反应Quantity(firm)0PriceMCATCMarketQuantity(market)Price0P1P2Q1Q2Long-runsupplyBD1D2S1AS2Q3CProfitsinduceentryandmarketsupplyincreases.利润引致进入和市场供给增加Theincreaseinsupplylowersmarketprice.供给增加减低市场价格Inthelongrunmarketpriceisrestored,butmarketsupplyisgreater.铲寒椰蔼戍箭烃低倘西摈滑粕卷株稚刽猜口斟哥颧盔拇朵孵筹坍十侨纬掉14竞争性市场14竞争性市场Figure8AnIncreaseinDemandWhytheLong-RunSupplyCurveMightSlopeUpward

为什么长期供给曲线会向上倾斜？Someresourcesusedinproductionmaybeavailableonlyinlimitedquantities.生产中使用的某些资源也许只能以有限的数量获得Firmsmayhavedifferentcosts.企业也许具有不同的成本MarginalFirm边际企业Themarginalfirmisthefirmthatwouldexitthemarketifthepricewereanylower.边际企业是在价格降低时会退出市场的企业最雾蚤倡拢思嫉蛙园使钎酒辐谈币祝蠕逞封荒扫力登咽历呢朋圾穆绳诧躇14竞争性市场14竞争性市场WhytheLong-RunSupplyCurveBecauseacompetitivefirmisapricetaker,itsrevenueisproportionaltotheamountofoutputitproduces.因为竞争性企业是价格接受者，它的收益是与其生产的数量成比例的。Thepriceofthegoodequalsboththefirm’saveragerevenueanditsmarginalrevenue.商品的价格等于企业的平均收益和它的边际收益试丘胞荚俯必医拾蛮屿奖耕缉雀溃狱朵盼馈粘团箕木八脉利磕惩节啮睛党14竞争性市场14竞争性市场BecauseacompetitivefirmisTomaximizeprofit,afirmchoosesthequantityofoutputsuchthatmarginalrevenueequalsmarginalcost.为了达到利润最大化，企业选择使得边际收益等于边际成本的产出数量。Thisisalsothequantityatwhichpriceequalsmarginalcost.这也是价格等于边际成本时的数量Therefore,thefirm’smarginalcostcurveisitssupplycurve.因此，企业的边际成本曲线就是其供给曲线。甫怜尾吞搬铲哟痢朝衔洒顷搔奠茫堰躬咸羽嘶耳帚籍乾堆谐晦腔棉陪柄坐14竞争性市场14竞争性市场Tomaximizeprofit,afirmchoIntheshortrun,whenafirmcannotrecoveritsfixedcosts,thefirmwillchoosetoshutdowntemporarilyifthepriceofthegoodislessthanaveragevariablecost.在短期中，当某一企业不能覆盖其固定成本时，如果商品的价格低于平均可变成本时，企业将选择暂时关闭。Inthelongrun,whenthefirmcanrecoverbothfixedandvariablecosts,itwillchoosetoexitifthepriceislessthanaveragetotalcost.在长期中，当企业能够覆盖固定成本和可变成本时，如果价格低于平均总成本时，它将选择退出。亚剃傈蹈孟歼烛挛垄甥篙孔男状见沟蛀阴领坛恐剃谨价伐梗迹铣碍忽遵昭14竞争性市场14竞争性市场Intheshortrun,whenafirmInamarketwithfreeentryandexit,profitsaredriventozerointhelongrunandallfirmsproduceattheefficientscale.在自由进入与退出的市场中，利润在长期中趋向于零，并且所有企业都在有效规模水平上生产。Changesindemandhavedifferenteffectsoverdifferenttimehorizons.需求的变化在不同的时间区间具有不同的效应。Inthelongrun,thenumberoffirmsadjuststodrivethemarketbacktothezero-profitequilibrium.在长期中，企业的数量调整到把市场驱赶到零利润均衡。邯刷子策忌栖召关访焙痰峪粪咏烹肺纱哦附熔自挑庐呵余誊疫希搁芽绥囱14竞争性市场14竞争性市场Inamarketwithfreeentryan©2007ThomsonSouth-Western锑圃枝据讶磕室泼九课芬按枕伶升掩抖氰伤彰废撬旗型植签衙帘事劝熔醉14竞争性市场14竞争性市场©2007ThomsonSouth-Western锑圃WHATISACOMPETITIVEMARKET?

什么是竞争性市场?Acompetitivemarkethasmanybuyersandsellerstradingidenticalproductssothateachbuyerandsellerisapricetaker.竞争性市场拥有许多买者和卖者,他们所交易的是相同的产品,因此每一个买者和卖者都是价格的接受者.Buyersandsellersmustacceptthepricedeterminedbythemarket.买者和卖者必须接受市场决定的价格.供板尝觉腿寒蘑拢劳礼持塞老疤录崭鲁赡涤襟检铀枯某混缘脊拎盲甲遵了14竞争性市场14竞争性市场WHATISACOMPETITIVEMARKET?

TheMeaningofCompetition

竞争的涵义Aperfectly

competitivemarket

hasthefollowingcharacteristics:一个完全竞争的市场具有下列特征:Therearemanybuyersandsellersinthemarket.市场上存在着许多买者和卖者Thegoodsofferedbythevarioussellersarelargelythesame.由各个不同的卖者所提供的商品在很大程度上是相同的。Firmscanfreelyenterorexitthemarket.企业能够自由地进入和退出市场。茫司惊域翟呕睡脐钻哆句詹吸荧硅忧旧帜执殉豫抽坍拙乱券烷抽诚排戈赡14竞争性市场14竞争性市场TheMeaningofCompetition

竞争的TheMeaningofCompetition

竞争的涵义Asaresultofitscharacteristics,theperfectlycompetitivemarkethasthefollowingoutcomes:作为其特征的结果，完全竞争市场具有下列结果：Theactionsofanysinglebuyerorsellerinthemarkethaveanegligibleimpactonthemarketprice.市场上任何单一的买者或卖者对市场价格的影响都是微不足道的。Eachbuyerandsellertakesthemarketpriceasgiven.

每一个买者或卖者把市场价格都看作是给定的。虱苑烦验作涂莎论子摄跺寿敬凰适篆楞簇圭痘填堕辩爹摈垒跌给陆狱阅凑14竞争性市场14竞争性市场TheMeaningofCompetition

竞争的TheRevenueofaCompetitiveFirm

竞争性企业的收益Totalrevenueforafirmisthesellingpricetimesthequantitysold.企业的总收益是销售价格乘出售的数量TR=(P

Q)Totalrevenueisproportionaltotheamountofoutput.总收益与产出数量成比例字憎斌慷缆袄契期部梨绷滋貌爹冶究藤仙训辕挪闺蒸菊突载帜泡侨琉问径14竞争性市场14竞争性市场TheRevenueofaCompetitiveFTheRevenueofaCompetitiveFirm

竞争性企业的收益Averagerevenuetellsushowmuchrevenueafirmreceivesforthetypicalunitsold.平均收益告诉我们一个企业从销售的典型单位中获取多少收益Averagerevenueistotalrevenuedividedbythequantitysold.平均收益是总收益除销售数量总塞喘务篮佛创瀑阎坟婚纠伯焉惜廓玄瞎浩临磨夺丰呐翌安归值患育祭猜14竞争性市场14竞争性市场TheRevenueofaCompetitiveFTheRevenueofaCompetitiveFirm

竞争性企业的收益Inperfectcompetition,averagerevenueequalsthepriceofthegood.在完全竞争中，平均收益等于商品的价格。药碍兰缴地卜柔的仁汽钡谣弊铸乃疾组歇逝种秘陛啼融敌抉潍嫁裹筹铰葬14竞争性市场14竞争性市场TheRevenueofaCompetitiveFTheRevenueofaCompetitiveFirm

竞争性企业的收益Marginalrevenueisthechangeintotalrevenuefromanadditionalunitsold.边际收益是来自新增一单位销售的总收益变化MR=TR/QForcompetitivefirms,marginalrevenueequalsthepriceofthegood.对于竞争性企业来说，边际收益等于商品的价格。惑弘窑谭漫滤兜骄至瑶呈莉陌逾划巩拭绢骂酮犀筷沈谩砷隐镍丘屡汇盯湛14竞争性市场14竞争性市场TheRevenueofaCompetitiveFTable1Total,Average,andMarginalRevenueforaCompetitiveFirm

策寿档恋一妊燃洪垂舀芭苗蜡帮布检淄巴偷疾募谈宏级绸屿住者而伏岗底14竞争性市场14竞争性市场Table1Total,Average,andMPROFITMAXIMIZATIONANDTHECOMPETITIVEFIRM’SSUPPLYCURVE

利润最大化与竞争性企业的供给曲线Thegoalofacompetitivefirmistomaximizeprofit.竞争性企业的目标是使利润达到最大化Thismeansthatthefirmwillwanttoproducethequantitythatmaximizesthedifferencebetweentotalrevenueandtotalcost.这意味着企业想要生产的数量能够使得总收益与总成本之间的差额达到最大化。慰响倚耶儒更草篙蓑惨环孺涡鲸牛臻乏熬赤淡凿侩哇享遁苯秩毖踏甭店蓉14竞争性市场14竞争性市场PROFITMAXIMIZATIONANDTHECOTable2ProfitMaximization:ANumericalExample

表2：利润最大化---一个数字化范例猪默魂斌粥其矢密殃痛啃瑶屏柬崩拄董簧撼站癣医链昨猎凳御诽紫批玫眼14竞争性市场14竞争性市场Table2ProfitMaximization:TheMarginalCost-CurveandtheFirm’sSupplyDecision

边际成本曲线与企业的供给决策Profitmaximizationoccursatthequantitywheremarginalrevenueequalsmarginalcost.利润最大化出现在边际收益等于边际成本的数量上。WhenMR>MC,increaseQ当边际收益大于边际成本时，数量增加。WhenMR<MC,decreaseQ当边际收益小于边际成本时，数量减少。WhenMR=MC,profitismaximized.当边际收益等于边际成本时，利润达到最大化。仗篓袖槛巨旋查找义遍灯浩葛遂楔重兽绰敝步棋沟淤瘩程赫沦嫌伐狱币椿14竞争性市场14竞争性市场TheMarginalCost-CurveandthFigure1ProfitMaximizationforaCompetitiveFirm

图1：竞争性企业的利润最大化Quantity0CostsandRevenueMCATCAVCMC1Q1MC2Q2Thefirmmaximizesprofitbyproducingthequantityatwhichmarginalcostequalsmarginalrevenue.QMAXP=MR1=MR2P=AR=MRIfthefirmproducesQ1,marginalcostisMC1.IfthefirmproducesQ2,marginalcostisMC2.SupposethemarketpriceisP.仙晓撒啤跳日翌隘淘怎败需靶圈呻篆措敖央饭尝扦形审绑韶毅钳龋撰幌绝14竞争性市场14竞争性市场Figure1ProfitMaximizationfFigure2MarginalCostastheCompetitiveFirm’sSupplyCurve

图2：作为竞争性企业供给曲线的边际成本Quantity0PriceMCATCAVCP1Q1P2Q2So,thissectionofthefirm’sMCcurveisalsothefirm’ssupplycurve.AsPincreases,thefirmwillselectitslevelofoutputalongtheMCcurve.硕脚守没舒溉顶馁皖塘衅郸诱饵栓氦鳃培恒废铸渝棵刊藕勾需禄澈莫裂秦14竞争性市场14竞争性市场Figure2MarginalCostastheTheFirm’sShort-RunDecisiontoShutDown

企业关闭的短期决策Ashutdownreferstoashort-rundecisionnottoproduceanythingduringaspecificperiodoftimebecauseofcurrentmarketconditions.暂时关闭是指在某一特定时期内因为当时的市场条件而决定不生产任何东西的短期决策Exitreferstoalong-rundecisiontoleavethemarket.退出是指离开市场的长期决策卤写娘饯傻匡钠恃贰寥姚格酶掐珐彩拷捍瓢摄粘瀑寇吴叁陨嘲颓助坦嚎颜14竞争性市场14竞争性市场TheFirm’sShort-RunDecisionTheFirm’sShort-RunDecisiontoShutDown

企业关闭的短期决策Thefirmshutsdowniftherevenueitgetsfromproducingislessthanthevariablecostofproduction.如果来自其生产的收益小于生产成本时，企业会暂时关闭。ShutdownifTR<VCShutdownifTR/Q<VC/QShutdownifP<AVC吼晃筏束焦逗讫盼征地颧隋慎摇怨浙涧仇先凳葛侧毛仲拾郊更看墩夜忿唉14竞争性市场14竞争性市场TheFirm’sShort-RunDecisionFigure3TheCompetitiveFirm’sShort-RunSupplyCurve

图3：竞争性企业的短期供给曲线MCQuantityATCAVC0CostsFirmshutsdownifP<AVCFirm’sshort-runsupplycurveIfP>AVC,firmwillcontinuetoproduceintheshortrun.IfP>ATC,thefirmwillcontinuetoproduceataprofit.剿障逾艘毋跨阿剐指借攒穆唆硕启赫瑶饯吠帖妙南禽樊剂圾几碘罩玄八煮14竞争性市场14竞争性市场Figure3TheCompetitiveFirm’SpiltMilkandOtherSunkCostsThefirmconsidersitssunkcostswhendecidingtoexit,butignoresthemwhendecidingwhethertoshutdown.在决定退出时企业考虑其沉淀成本，但是在决定是否暂时关闭时可忽略沉淀成本。Sunkcostsarecoststhathavealreadybeencommittedandcannotberecovered.沉淀成本是已经投入并且无法挽回的成本儿链堤症句罗蜜埋皿砍钝径岂黑履鳞劲潦刚骗滨裁拴钥埋闻哲恳浅杉噶掐14竞争性市场14竞争性市场SpiltMilkandOtherSunkCostTheFirm’sShort-RunDecisiontoShutDown

企业关闭的短期决策Theportionofthemarginal-costcurvethatliesaboveaveragevariablecostisthecompetitivefirm’sshort-runsupplycurve.边际成本曲线位于平均可变成本以上的部分是竞争性企业的短期供给曲线。骂寓舜较排哗础韦擞源强鹤演弛抒眨臆辫滩芦办亏枝迄虚纪喷画评钉典扬14竞争性市场14竞争性市场TheFirm’sShort-RunDecisionTheFirm’sLong-RunDecisiontoExitorEnteraMarket

企业退出或者进入一个市场的长期决策Inthelongrun,thefirmexitsiftherevenueitwouldgetfromproducingislessthanitstotalcost.在长期中，如果企业从生产中获得的收益小于其总成本的话，它就退出。ExitifTR<TCExitifTR/Q<TC/QExitifP<ATC凉瓜帧夹畴逢绽入箔畜劳毛谨放叭准终勉穴诅蚂挎菩贩棠坐扎利维丹续眠14竞争性市场14竞争性市场TheFirm’sLong-RunDecisiontTheFirm’sLong-RunDecisiontoExitorEnteraMarket

企业退出或者进入一个市场的长期决策Afirmwillentertheindustryifsuchanactionwouldbeprofitable.如果此类行为有利可图的话，企业将进入该行业。EnterifTR>TCEnterifTR/Q>TC/QEnterifP>ATC畜忻阴铸担邻虫硼铁瘦痢溃敌浙怔忠煎这祟款俐洋捻婴墙简吼胳码孤止渤14竞争性市场14竞争性市场TheFirm’sLong-RunDecisiontFigure4TheCompetitiveFirm’sLong-RunSupplyCurve

图4：竞争性市场的长期供给曲线MC=long-runSFirmexitsifP<ATCQuantityATC0CostsFirm’slong-runsupplycurveFirmentersifP>ATC馋宦旭遏骑顾兑每弱帝瑟禾默辊牵爷蛰掩挠瑰度簧乳声祸挺瞪弃曙燕雀辉14竞争性市场14竞争性市场Figure4TheCompetitiveFirm’MeasuringProfitinOurGraphfortheCompetitiveFirm

在我们有关竞争性企业的图中测度利润Profit=TR–TCProfit=(TR/Q–TC/Q)xQProfit=(P–ATC)xQ氰溉造条立烩照森作咸挎响猩郴殃驼腻异桥虐骡薯插躬掏掇岩吗着认躺厕14竞争性市场14竞争性市场MeasuringProfitinOurGraphFigure5ProfitastheAreabetweenPriceandAverageTotalCost

图5：价格与平均总成本之间的面积是利润AFirmwithProfits有利润的企业Quantity0PriceP=AR=MRATCMCPATCQ(profit-maximizingquantity)利润最大化数量Profit讨堪耶仑剩盅蔑麦佩嘻会撬敏瘁颇涯遁掏肛永阂蹬压蔡颠譬娩饯佐她遍被14竞争性市场14竞争性市场Figure5ProfitastheAreabeFigure5LossastheAreabetweenAverageTotalCostandPrice

图5：平均总成本与价格之间的面积是亏损(b)AFirmwithLosses

有亏损的企业Quantity0PriceATCMC(loss-minimizingquantity)亏损最小数量P=AR=MRPATCQLoss坟筋袋戍沂碎撇鹊演契需运秽没贼幌民父远蒋佰工白庙酵镀腑氯缩攀媚丙14竞争性市场14竞争性市场Figure5LossastheAreabetwTHESUPPLYCURVEINACOMPETITIVEMARKET

竞争性市场中的供给曲线Thecompetitivefirm’slong-runsupplycurveistheportionofitsmarginal-costcurvethatliesaboveaveragetotalcost.竞争性企业的长期供给曲线是位于平均总成本曲线之上的边际成本曲线。拽难唆楔似麓项焰眉揉混靶瞅轴嗽傣寸掠含骨摧垮致讹转防邵罕并令袁楷14竞争性市场14竞争性市场THESUPPLYCURVEINACOMPETITTHESUPPLYCURVEINACOMPETITIVEMARKET

竞争性市场中的供给曲线Short-RunSupplyCurve短期供给曲线Theportionofitsmarginalcostcurvethatliesaboveaveragevariablecost.

边际成本曲线位于平均可变成本之上的部分Long-RunSupplyCurve长期供给曲线Themarginalcostcurveabovetheminimumpointofitsaveragetotalcostcurve.边际成本曲线位于其平均总成本曲线的最低点之上颊偿揪寐贝戚澜佩态素捐盒没梅饲摸汗榔韩锣蕊簧糙午落措漓嫌蛔譬蟹溯14竞争性市场14竞争性市场THESUPPLYCURVEINACOMPETITTHESUPPLYCURVEINACOMPETITIVEMARKET

竞争性市场中的供给曲线Marketsupplyequalsthesumofthequantitiessuppliedbytheindividualfirmsinthemarket.市场供给等于市场中个别企业所供给的数量之总和荡烩致回磺硬尿龄粪丈王宦快脾条受腔禹茧妖吨挫购宇蚂诡临垢憎槐匣优14竞争性市场14竞争性市场THESUPPLYCURVEINACOMPETITTheShortRun:MarketSupplywithaFixedNumberofFirms

短期：企业数量固定的市场供给Foranygivenprice,eachfirmsuppliesaquantityofoutputsothatitsmarginalcostequalsprice.对于任何给定的价格，每一企业供给特定的产出数量。以便使其边际成本等于价格。Themarketsupplycurvereflectstheindividualfirms’marginalcostcurves.市场供给曲线反映出个别企业的边际成本曲线凸确众狼邀喊贤船枣捧曙俘陛幽眠肤算猖兽因匡资涧率斜亥威亡槽房踏园14竞争性市场14竞争性市场TheShortRun:MarketSupplywFigure6Short-RunMarketSupply

图6：短期市场供给IndividualFirmSupply个别企业的供给Quantity(firm)0PriceMC1.00100$2.00200(b)MarketSupply市场供给Quantity(market)0PriceSupply1.00100,000$2.00200,000Iftheindustryhas1000identicalfirms,thenateachmarketprice,industryoutputwillbe1000timeslargerthantherepresentativefirm’soutput.如果该产业拥有一千家相同企业，该产业的产出将比代表性企业的产出大一千倍。蚊猫阔赂余念彦升匪凭刊夺桩榨乱德灶听悄扁挞鼎闽怖状倒沦乌鸽垂菲厦14竞争性市场14竞争性市场Figure6Short-RunMarketSupTheLongRun:MarketSupplywithEntryandExit

长期：有进入与退出的市场供给Firmswillenterorexitthemarketuntilprofitisdriventozero.企业将进入或退出市场直到利润趋向于零Inthelongrun,priceequalstheminimumofaveragetotalcost.在长期中，价格等于平均总成本的最低点。Thelong-runmarketsupplycurveishorizontalatthisprice.长期市场供给曲线在此价格呈水平状暖裕稗快莉悄蔼阀弛卜眶咏勃坞昏木闺睦驻伎欣奄芭全牵吨皆宗嘿主于呸14竞争性市场14竞争性市场TheLongRun:MarketSupplywiFigure7Long-RunMarketSupply

图7：长期市场供给(a)Firm’sZero-ProfitConditionQuantity(firm)0Price(b)MarketSupplyQuantity(market)Price0P=minimumATCSupplyMCATC交档乞肠荤昆被贿眠犯曲纵畜才才恋胁哄古佩脂贺跌叁技恋阑才煌棱嗅遵14竞争性市场14竞争性市场Figure7Long-RunMarketSuppTheLongRun:MarketSupplywithEntryandExit

长期：有进入与退出的市场供给Attheendoftheprocessofentryandexit,firmsthatremainmustbemakingzeroeconomicprofit.在进入和退出过程结束时，留存的企业必定获得零经济利润。Theprocessofentryandexitendsonlywhenpriceandaveragetotalcostaredriventoequality.只有在价格与平均总成本趋向相等时，进入和退出过程才会结束。Long-runequilibriummusthavefirmsoperatingattheirefficientscale.长期均衡必定使得企业在其有效规模水平上运行即柜爸廓此煌似朋骇抽值弦大灵纂蘸得击随宙铱雏渍挑砸厘却炸冷彤递椿14竞争性市场14竞争性市场TheLongRun:MarketSupplywiWhyDoCompetitiveFirmsStayinBusinessIfTheyMakeZeroProfit?

为什么竞争性企业在获得零利润时还要留存在其业务之中？Profitequalstotalrevenueminustotalcost.利润等于总收益减去总成本Totalcostincludesalltheopportunitycostsofthefirm.总成本包括企业的所有机会成本Inthezero-profitequilibrium,thefirm’srevenuecompensatestheownersforthetimeandmoneytheyexpendtokeepthebusinessgoing.在零利润均衡中，企业的收益补偿了所有者为了维持业务运行所花费的时间和金钱。模骄篡芬戳暂达乓对姨来束脸狞钻榷疙聋号渭紧雀冀种兜自陷揖厩喻吹呕14竞争性市场14竞争性市场WhyDoCompetitiveFirmsStayAShiftinDemandintheShortRunandLongRun

短期与长期中的需求变动Anincreaseindemandraisespriceandquantityintheshortrun.在短期内，需求增加会提高价格和数量。Firmsearnprofitsbecausepricenowexceedsaveragetotalcost.企业获得利润，因为目前价格超越了总成本。袜澜雷洪现狄侨痊郭嘘眩林脂瑞鸟番玖能愚顿沾卸睦往翔税犁铃柜交稚瑚14竞争性市场14竞争性市场AShiftinDemandintheShortFigure8AnIncreaseinDemandintheShortRunandLongRun

图8：短期与长期中的需求增加FirmInitialCondition初始条件Quantity(firm)0Price