微观经济学——第八章

第一页，共55页。CHAPTER8OUTLINE8.1PerfectlyCompetitiveMarkets8.2ProfitMaximization8.3MarginalRevenue,MarginalCost,andProfitMaximization8.4ChoosingOutputintheShortRun8.5TheCompetitiveFirm’sShort-RunSupplyCurve8.6TheShort-RunMarketSupplyCurve8.7ChoosingOutputintheLongRun8.8TheIndustry’sLong-RunSupplyCurve第二页，共55页。PERFECTLYCOMPETITIVEMARKETS8.1Themodelofperfectcompetitionrestsonthreebasicassumptions:(1)pricetaking,(2)producthomogeneity,and(3)freeentryandexit.PriceTakingBecauseeachindividualfirmsellsasufficientlysmallproportionoftotalmarketoutput,itsdecisionshavenoimpactonmarketprice.●pricetakerFirmthathasnoinfluenceovermarketpriceandthustakesthepriceasgiven.ProductHomogeneityWhentheproductsofallofthefirmsinamarketareperfectlysubstitutablewithoneanother—thatis,whentheyarehomogeneous—nofirmcanraisethepriceofitsproductabovethepriceofotherfirmswithoutlosingmostorallofitsbusiness.第三页，共55页。PERFECTLYCOMPETITIVEMARKETS8.1FreeEntryandExit●freeentry(orexit)Conditionunderwhichtherearenospecialcoststhatmakeitdifficultforafirmtoenter(orexit)anindustry.WhenIsaMarketHighlyCompetitive?Becausefirmscanimplicitlyorexplicitlycollude(或明或暗地串通(chuàntōng))insettingprices,thepresenceofmanyfirmsisnotsufficientforanindustrytoapproximateperfectcompetition.Conversely,thepresenceofonlyafewfirmsinamarketdoesnotruleoutcompetitivebehavior.第四页，共55页。股票市场是不是完全(wánquán)竞争纽约证卷交易所的交易量约占上市公司股票总量的80%纳斯达克（Nasdaq）（全国(quánɡuó)证卷经销商协会自动报价系统）是一个数千家未上市公司股票的电子交易系统，其股票是以及百家经纪商和经销商为基础进行的交易第五页，共55页。PROFITMAXIMIZATION8.2DoFirmsMaximizeProfit?Theassumptionofprofitmaximizationisfrequentlyusedinmicroeconomicsbecauseitpredictsbusinessbehaviorreasonablyaccuratelyandavoidsunnecessaryanalyticalcomplications.Forsmallerfirmsmanagedbytheirowners,profitislikelytodominatealmostalldecisions.Inlargerfirms,however,managerswhomakeday-to-daydecisionsusuallyhavelittlecontactwiththeowners(i.e.thestockholders).Inanycase,firmsthatdonotcomeclosetomaximizingprofitarenotlikelytosurvive.Firmsthatdosurviveincompetitiveindustriesmakelong-runprofitmaximizationoneoftheirhighestpriorities.AlternativeFormsofOrganization●cooperativeAssociationofbusinessesorpeoplejointlyownedandoperatedbymembersformutualbenefit.第六页，共55页。DoFirmsMaximizeProfit?追求利润是企业生存的必要条件(bìyàotiáojiàn)。企业行为在短期内可能会偏离利润目标，但长期而言，在激烈竞争的市场上它就会被淘汰一个补贴公共电视台的企业似乎看起来是有公益精神和利他主义的，但这一慈善行为可能正是该企业的长期经济利益之所在，因为它给企业及其产品创造了商誉。第七页，共55页。MARGINALREVENUE,MARGINALCOST,ANDPROFITMAXIMIZATION8.3●profitDifferencebetweentotalrevenueandtotalcost.π(q)=R(q)−C(q)●marginalrevenueChangeinrevenueresultingfromaone-unitincreaseinoutput.ProfitMaximizationintheShortRunAfirmchoosesoutputq*,sothatprofit,thedifferenceABbetweenrevenueRandcostC,ismaximized.Atthatoutput,marginalrevenue(theslopeoftherevenuecurve)isequaltomarginalcost(theslopeofthecostcurve).Δπ/Δq=ΔR/Δq−ΔC/Δq=0MR(q)=MC(q)第八页，共55页。利润(lìrùn)最大化的条件Maxπ(q)=R(q)-C(q)方程(fāngchéng)对q求导，令其值为0dπ(q)/dq=dR(q)/dq-dC(q)/dq=0dR(q)/dq=dC(q)/dq利润最大时有：MR=MC第九页，共55页。MARGINALREVENUE,MARGINALCOST,ANDPROFITMAXIMIZATION8.3DemandandMarginalRevenueforaCompetitiveFirmDemandCurveFacedbyaCompetitiveFirmAcompetitivefirmsuppliesonlyasmallportionofthetotaloutputofallthefirmsinanindustry.Therefore,thefirmtakesthemarketpriceoftheproductasgiven,choosingitsoutputontheassumptionthatthepricewillbeunaffectedbytheoutputchoice.In(a)thedemandcurvefacingthefirmisperfectlyelastic,eventhoughthemarketdemandcurvein(b)isdownwardsloping.第十页，共55页。MARGINALREVENUE,MARGINALCOST,ANDPROFITMAXIMIZATION8.3Thedemanddcurvefacinganindividualfirminacompetitivemarketisbothitsaveragerevenuecurveanditsmarginalrevenuecurve.Alongthisdemandcurve,marginalrevenue,averagerevenue,andpriceareallequal.ProfitMaximizationbyaCompetitiveFirmMC(q)=MR=PDemandandMarginalRevenueforaCompetitiveFirm第十一页，共55页。CHOOSINGOUTPUTINTHESHORTRUN8.4Short-RunProfitMaximizationbyaCompetitiveFirmMarginalrevenueequalsmarginalcostatapointatwhichthemarginalcostcurveisrising.OutputRule:Ifafirmisproducinganyoutput,itshouldproduceatthelevelatwhichmarginalrevenueequalsmarginalcost.第十二页，共55页。CHOOSINGOUTPUTINTHESHORTRUN8.4TheShort-RunProfitofaCompetitiveFirmACompetitiveFirmMakingaPositiveProfitIntheshortrun,thecompetitivefirmmaximizesitsprofitbychoosinganoutputq*atwhichitsmarginalcostMCisequaltothepriceP(ormarginalrevenueMR)ofitsproduct.TheprofitofthefirmismeasuredbytherectangleABCD.Anychangeinoutput,whetherloweratq1orhigheratq2,willleadtolowerprofit.第十三页，共55页。选择短期(duǎnqī)产量MC=MR处的产量水平(shuǐpíng)使利润最大Q1处利润损失：AR=MR=PMCQ0Q1Q2PQQ2处还可以(kěyǐ)增加的利润为：第十四页，共55页。竞争性厂商的短期(duǎnqī)赢利能力平均利润=[R(Q)-C(Q)]/Q=R(Q)/Q--C(Q)/Q=AR-AC线段AB代 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 平均利润总利润=平均利润×产量为绿色(lǜsè)矩形AR=MR=PMCATCQ0AB第十五页，共55页。CHOOSINGOUTPUTINTHESHORTRUN8.4TheShort-RunProfitofaCompetitiveFirmACompetitiveFirmIncurringLossesAcompetitivefirmshouldshutdownifpriceisbelowAVC.Thefirmmayproduceintheshortrunifpriceisgreaterthanaveragevariablecost.Shut-DownRule:Thefirmshouldshutdownifthepriceoftheproductislessthantheaveragevariablecostofproductionattheprofit-maximizingoutput.第十六页，共55页。何时退出(tuìchū)行业当PAVC，企业还会继续产生当P 书 关于书的成语关于读书的排比句社区图书漂流公约怎么写关于读书的小报汉书pdf 馆、一个酒吧和5个可容纳80名宾客的大宴会厅。“冲突乐队（TheFray）”的26岁主唱艾萨克·史雷德幸运继承他价值750万英镑(约合1482万美元)的豪华庄园。第十九页，共55页。曼索尔庄园的维护费用十分(shífēn)昂贵，仅一个月的供暖费用就需要1000英镑(1975美元)，而本杰明却没有任何儿女继承人，一旦本杰明去世，曼索尔庄园将面临无人继承和照管的凄惨境地。本杰明称：“事实上，只要有人愿意支付维护费用，并且照管好这个地方，我并不介意谁来继承它。但是我的亲戚都拥有自己的豪宅，没有一个人愿接受这样一座‘旧房子’。”该庄园属于英国文物遗产，修理任何地方都必须报英国遗产部门批准，让许多富翁望而却步。”第二十页，共55页。THECOMPETITIVEFIRM’SSHORT-RUNSUPPLYCURVE8.5Thefirm’ssupplycurveistheportionofthemarginalcostcurveforwhichmarginalcostisgreaterthanaveragevariablecost.TheShort-RunSupplyCurveforaCompetitiveFirmIntheshortrun,thefirmchoosesitsoutputsothatmarginalcostMCisequaltopriceaslongasthefirmcoversitsaveragevariablecost.Theshort-runsupplycurveisgivenbythecrosshatchedportionofthemarginalcostcurve.第二十一页，共55页。THECOMPETITIVEFIRM’SSHORT-RUNSUPPLYCURVE8.5TheResponseofaFirmtoaChangeinInputPriceWhenthemarginalcostofproductionforafirmincreases(fromMC1toMC2),thelevelofoutputthatmaximizesprofitfalls(fromq1toq2).Theshadedareainthefiguregivesthetotalsavingstothefirm(orequivalently,thereductioninlostprofit)associatedwiththereductioninoutputfromq1toq2.TheShort-RunProfitofaCompetitiveFirm第二十二页，共55页。THECOMPETITIVEFIRM’SSHORT-RUNSUPPLYCURVE8.5Althoughplentyofcrudeoilisavailable,theamountthatyourefinedependsonthecapacityoftherefineryandthecostofproduction.TheShort-RunProductionofPetroleumProductsAstherefineryshiftsfromoneprocessingunittoanother,themarginalcostofproducingpetroleumproductsfromcrudeoilincreasessharplyatseverallevelsofoutput.Asaresult,theoutputlevelcanbeinsensitivetosomechangesinpricebutverysensitivetoothers.第二十三页，共55页。短期供应(gōngyìng)曲线的移动当投入要素(yàosù)价格变化时，同样产量水平的MC会改变，供应曲线将发生移动DMCQP第二十四页，共55页。启示(qǐshì)：竞争性厂商的短期赢利能力价格是市场供求总量决定，企业是价格的接受者短期(duǎnqī)赢利能力决定于生产的企业的边际成本和平均成本进一步决定于生产要素的价格和企业技术和管理水平决定的要素的边际产品第二十五页，共55页。定位(dìngwèi)在全球生产网络价值链的低端处于市场、资金、品牌、技术全部依靠国外，而自己只是加工生产的发展状况一个芭比娃娃，在美国卖价是10美元，从中国出口的价格大约为3美元，其中头发进口于日本，橡胶来自(láizì)东南亚，布料来自(láizì)越南，中国只赚取0.35美元的加工费.没有价格决定能力第二十六页，共55页。资源依赖型经济(jīngjì)增长以单位GDP产出能耗量表征的能源利用效率，我国与发达国家差距(chājù)非常之大。日本为1，意大利为1.33，法国为1.5，德国为1.5，英国为2.17，美国为2.67，加拿大为3.5，而我国高达11.5。每吨 标准 excel标准偏差excel标准偏差函数exl标准差函数国标检验抽样标准表免费下载红头文件格式标准下载 煤的产出率，我国相当于美国的29.6%，欧盟的16.8%。日本的10.3%。----摘自中国城市环境卫生协会《环卫信息》第二十七页，共55页。对资源(zīyuán)的定价能力低同济大学教授：为什么我国作为铁矿石的一个重要采购大国却不具有对铁矿石价格的议价权？回答：1、铁矿石价格的谈判历史有30~40年，中国进入才3年，谈判规则是别人制定的，中国人目前只能执行，处于不利地位。2、价格谈判是三家对三家，中、日、英对巴西、澳大利亚的三家大矿山(kuàngshān)，日、英产品的附加值高，对价格上涨的承受力高，成本价格上涨对其最终产品价格的影响只有8%0，它们也希望借价格上涨打压中国企业，谈判不出力中国企业不团结，一方面价格谈判希望降价，另一方面有的企业又囤积购买，待价而沽，破坏谈判第二十八页，共55页。PMCACMC’Q1Q2AC’第二十九页，共55页。THESHORT-RUNMARKETSUPPLYCURVE8.6IndustrySupplyintheShortRunTheshort-runindustrysupplycurveisthesummationofthesupplycurvesoftheindividualfirms.Becausethethirdfirmhasaloweraveragevariablecostcurvethanthefirsttwofirms,themarketsupplycurveSbeginsatpriceP1andfollowsthemarginalcostcurveofthethirdfirmMC3untilpriceequalsP2,whenthereisakink.ForP2andallpricesaboveit,theindustryquantitysuppliedisthesumofthequantitiessuppliedbyeachofthethreefirms.ElasticityofMarketSupplyEs=(ΔQ/Q)/(ΔP/P)第三十页，共55页。价格上升(shàngshēng)对行业供应量的影响产品价格上升有两种效应(xiàoyìng)：产品供应量增加原材料成本上升，MC上升，供应曲线内移动，供应量降低（中国资源依赖型经济增长带动原材料价格上涨，进一步阻碍中国经济增长）行业供应曲线反应的是这两者的中和第三十一页，共55页。THESHORT-RUNMARKETSUPPLYCURVE8.6Table8.1TheWorldCopperIndustry(2006)CountryAustraliaCanadaChileIndonesiaPeruPolandRussiaUSZambiaCountry9506005,4008001,0505307201,220540AnnualProduction(ThousandMetricTons)CountryMarginalCost(DollarsPerPound)SourceforAnnualProductionData:U.S.GeologicalSurvey,MineralCommoditySummaries,January2007.SourceforMarginalCostData:CharlesRiverAssociates’Estimates.第三十二页，共55页。THESHORT-RUNMARKETSUPPLYCURVE8.6TheShort-RunWorldSupplyofCopperThesupplycurveforworldcopperisobtainedbysummingthemarginalcostcurvesforeachofthemajorcopper-producingcountries.Thesupplycurveslopesupwardbecausethemarginalcostofproductionrangesfromalowof65centsinRussiatoahighof$1.30inCanada.第三十三页，共55页。THESHORT-RUNMARKETSUPPLYCURVE8.6ProducerSurplusintheShortRun●producersurplusSumoverallunitsproducedbyafirmofdifferencesbetweenthemarketpriceofagoodandthemarginalcostofproduction.ProducerSurplusforaFirmTheproducersurplusforafirmismeasuredbytheyellowareabelowthemarketpriceandabovethemarginalcostcurve,betweenoutputs0andq*,theprofit-maximizingoutput.Alternatively,itisequaltorectangleABCDbecausethesumofallmarginalcostsuptoq*isequaltothevariablecostsofproducingq*.第三十四页，共55页。THESHORT-RUNMARKETSUPPLYCURVE8.6ProducerSurplusintheShortRunProducerSurplusforaMarketTheproducersurplusforamarketistheareabelowthemarketpriceandabovethemarketsupplycurve,between0andoutputQ*.ProducerSurplusversusProfitProducersurplus=PS=R−VCProfit=π=R−VC−FC第三十五页，共55页。MC生产者剩余(shèngyú)Q*0P生产者剩余为绿矩形(jǔxíng)面积生产者剩余=R（Q*）-VC（Q*）AVC第三十六页，共55页。CHOOSINGOUTPUTINTHELONGRUN8.7Long-RunProfitMaximizationOutputChoiceintheLongRunThefirmmaximizesitsprofitbychoosingtheoutputatwhichpriceequalslong-runmarginalcostLMC.Inthediagram,thefirmincreasesitsprofitfromABCDtoEFGDbyincreasingitsoutputinthelongrun.Thelong-runoutputofaprofit-maximizingcompetitivefirmisthepointatwhichlong-runmarginalcostequalstheprice.第三十七页，共55页。CHOOSINGOUTPUTINTHELONGRUN8.7Long-RunProfitMaximizationOutputChoiceintheLongRunThefirmmaximizesitsprofitbychoosingtheoutputatwhichpriceequalslong-runmarginalcostLMC.Inthediagram,thefirmincreasesitsprofitfromABCDtoEFGDbyincreasingitsoutputinthelongrun.Thelong-runoutputofaprofit-maximizingcompetitivefirmisthepointatwhichlong-runmarginalcostequalstheprice.第三十八页，共55页。CHOOSINGOUTPUTINTHELONGRUN8.7Long-RunCompetitiveEquilibriumAccountingProfitandEconomicProfitπ=R−wL−rKZeroEconomicProfit●zeroeconomicprofitAfirmisearninganormalreturnonitsinvestment—i.e.,itisdoingaswellasitcouldbyinvestingitsmoneyelsewhere.第三十九页，共55页。CHOOSINGOUTPUTINTHELONGRUN8.7Long-RunCompetitiveEquilibriumEntryandExitLong-RunCompetitiveEquilibriumInitiallythelong-runequilibriumpriceofaproductis$40perunit,shownin(b)astheintersectionofdemandcurveDandsupplycurveS1.In(a)weseethatfirmsearnpositiveprofitsbecauselong-runaveragecostreachesaminimumof$30(atq2).PositiveprofitencouragesentryofnewfirmsandcausesashifttotherightinthesupplycurvetoS2,asshownin(b).Thelong-runequilibriumoccursatapriceof$30,asshownin(a),whereeachfirmearnszeroprofitandthereisnoincentivetoenterorexittheindustry.第四十页，共55页。厂商与市场(shìchǎng)的协调QPQPDS1ACMC（S）……S2SDP*厂商(chǎngshāng)的情况市场(shìchǎng)的情况第四十一页，共55页。厂商的长期(chángqī)均衡QPQPDS’ACMC（S）S’’SDP*厂商(chǎngshāng)的情况市场(shìchǎng)的情况D’D’’长期均衡：边际成本=平均成本=市场价格第四十二页，共55页。CHOOSINGOUTPUTINTHELONGRUN8.7Long-RunCompetitiveEquilibriumEntryandExitInamarketwithentryandexit,afirmenterswhenitcanearnapositivelong-runprofitandexitswhenitfacestheprospectofalong-runloss.●long-runcompetitiveequilibriumAllfirmsinanindustryaremaximizingprofit,nofirmhasanincentivetoenterorexit,andpriceissuchthatquantitysuppliedequalsquantitydemanded.Along-runcompetitiveequilibriumoccurswhenthreeconditionshold:Allfirmsintheindustryaremaximizingprofit.2.Nofirmhasanincentiveeithertoenterorexittheindustrybecauseallfirmsareearningzeroeconomicprofit.3.Thepriceoftheproductissuchthatthequantitysuppliedbytheindustryisequaltothequantitydemandedbyconsumers.第四十三页，共55页。CHOOSINGOUTPUTINTHELONGRUN8.7Long-RunCompetitiveEquilibriumFirmsHavingIdenticalCostsToseewhyalltheconditionsforlong-runequilibriummusthold,assumethatallfirmshaveidenticalcosts.Nowconsiderwhathappensiftoomanyfirmsentertheindustryinresponsetoanopportunityforprofit.Theindustrysupplycurvewillshiftfurthertotheright,andpricewillfall.FirmsHavingDifferentCostsNowsupposethatallfirmsintheindustrydonothaveidenticalcostcurves.Thedistinctionbetweenaccountingprofitandeconomicprofitisimportanthere.Ifapatentisprofitable,otherfirmsintheindustrywillpaytouseit.Theincreasedvalueofapatentthusrepresentsanopportunitycosttothefirmthatholdsit.第四十四页，共55页。CHOOSINGOUTPUTINTHELONGRUN8.7Long-RunCompetitiveEquilibriumTheOpportunityCostofLandThereareotherinstancesinwhichfirmsearningpositiveaccountingprofitmaybeearningzeroeconomicprofit.Suppose,forexample,thataclothingstorehappenstobelocatednearalargeshoppingcenter.Theadditionalflowofcustomerscansubstantiallyincreasethestore’saccountingprofitbecausethecostofthelandisbasedonitshistoricalcost.EconomicRent●economicrentAmountthatfirmsarewillingtopayforaninputlesstheminimumamountnecessarytoobtainit.第四十五页，共55页。CHOOSINGOUTPUTINTHELONGRUN8.7Inthelongrun,inacompetitivemarket,theproducersurplusthatafirmearnsontheoutputthatitsellsconsistsoftheeconomicrentthatitenjoysfromallitsscarceinputs.ProducerSurplusintheLongRun第四十六页，共55页。CHOOSINGOUTPUTINTHELONGRUN8.7FirmsEarnZeroProfitinLong-RunEquilibriumInlong-runequilibrium,allfirmsearnzeroeconomicprofit.In(a),abaseballteaminamoderate-sizedcitysellsenoughticketssothatprice($7)isequaltomarginalandaveragecost.In(b),thedemandisgreater,soa$10pricecanbecharged.Theteamincreasessalestothepointatwhichtheaveragecostofproductionplustheaverageeconomicrentisequaltotheticketprice.Whentheopportunitycostassociatedwithowningthefranchise(专营权)istakenintoaccount,theteamearnszeroeconomicprofit.ProducerSurplusintheLongRun第四十七页，共55页。THEINDUSTRY’SLONG-RUNSUPPLYCURVE8.8Constant-CostIndustry●constant-costindustryIndustrywhoselong-runsupplycurveishorizontal.Long-RunSupplyinaConstant-CostIndustryIn(b),thelong-runsupplycurveinaconstant-costindustryisahorizontallineSL.Whendemandincreases,initiallycausingapricerise(representedbyamovefrompointAtopointC),thefirminitiallyincreasesitsoutputfromq1toq2,asshownin(a).Buttheentryofnewfirmscausesashifttotherightinindustrysupply.Becauseinputpricesareunaffectedbytheincreasedoutputoftheindustry,entryoccursuntiltheoriginalpriceisobtained(atpointBin(b)).Thelong-runsupplycurveforaconstant-costindustryis,therefore,ahorizontallineatapricethatisequaltothelong-runminimumaveragecostofproduction.第四十八页，共55页。THEINDUSTRY’SLONG-RUNSUPPLYCURVE8.8Increasing-CostIndustry●increasing-costindustryIndustrywhoselong-runsupplycurveisupwardsloping.Long-RunSupplyinanIncreasing-CostIndustryIn(b),thelong-runsupplycurveinanincreasing-costindustryisanupward-slopingcurveSL.Whendemandincreases,initiallycausingapricerise,thefirmsincreasetheiroutputfromq1toq2in(a).Inthatcase,theentryofnewfirmscausesashifttotherightinsupplyfromS1toS2.Becauseinputpricesincreaseasaresult,thenewlong-runequilibriumoccursatahigherpricethantheinitialequilibrium.Inanincreasing-costindustry,thelong-runindustrysupplycurveisupwardsloping.第四十九页，共55页。成本(chéngběn)递减行业投入品价格(jiàgé)由于规模效应的影响将随着产量的增加而下降，MC线下移P3 总结 初级经济法重点总结下载党员个人总结TXt高中句型全总结.doc高中句型全总结.doc理论力学知识点总结pdf CHAPTER8OUTLINE。Theassumptionofprofitmaximizationisfrequentlyusedinmicroeconomicsbecauseitpredictsbusinessbehaviorreasonablyaccuratelyandavoidsunnecessaryanalyticalcomplications.第五十五页，共55页。