英文9--完全竞争

MarketstructureWhatismarket?Howtodividethemarket？Thebuyers’quantityandscaleThesellers’quantityandscaleTheproductEntrybarrieAnyforcethatpreventsfirmsfromenteringanewmarketExamples:monopolyoverinputs,largefixedinvestment,distributionnetwork,legalentrybarriers(copyrights,patent),(illegal)anti-competitivepracticesInformationFourMarketstructuresPerfectlycompetitivemarketMonopolisticcompetitionoligopolymonopolyCompetitiveintensityCompetitiveintensityCompetitiveintensitydependsmoreonthenatureofcompetitionthanthenumberofcompetitors.Competitionismostintensewhenfirmscompeteonprice.Themoreintensecompetitionis,thelowerisfirmprofitability.市场结构：许多企业完全竞争完全垄断寡头垄断企业数量？几家企业垄断竞争有差别产品一家企业产品类型相同产品5MarketstructureoverviewNumberTypeofPoweroffirmExamplesMarketofsellersproductoverpriceStructureoneuniqueconsiderablepublicutilitiesmonopolyafewsameordifferentsomeoil,airlineoligopolymanydifferentiatedsomeretailtrademonopolisticcompetitionmanysamenoneagricultureperfectcompetition6市场结构及其特征表厂商个数产品同质性进入条件信息的完全性完全竞争大量同质自由完全信息完全垄断唯一无相近的替代品封锁难以获得信息寡头垄断少数同质或有差别困难不完全信息垄断竞争大量有差别自由不完全信息TheMeaningofCompetitionAperfectlycompetitivemarkethasthefollowingcharacteristics:Therearemanybuyersandsellersinthemarket.Thegoodsofferedbythevarioussellersarelargelythesame.Firmscanfreelyenterorexitthemarket.perfectcompetitivemarket/CompetitiveMarket4characteristicsofperfectcompetitivemarket:P154TheMeaningofCompetitionAsaresultofitscharacteristics,theperfectlycompetitivemarkethasthefollowingoutcomes:Theactionsofanysinglebuyerorsellerinthemarkethaveanegligibleimpactonthemarketprice.Eachbuyerandsellertakesthemarketpriceasgiven.TheMeaningofCompetitionBuyersandsellersincompetitivemarketsaresaidtobepricetakers.Buyersandsellersmustacceptthepricedeterminedbythemarket.Qp12ＰＱＰＱ（Demandcurve）Lawofdemand?DDSRevenueofaCompetitiveFirmTotalrevenueforafirmisthesellingpricetimesthequantitysold.TR=PXQTotalrevenueisproportionaltotheamountofoutput.RevenueofaCompetitiveFirmAveragerevenuetellsushowmuchrevenueafirmreceivesforthetypicalunitsold.QRevenueofaCompetitiveFirmInperfectcompetition,averagerevenueequalsthepriceofthegood.Averagerevenue=TotalrevenueQuantity=(PriceQuantity)Quantity=PriceQaveragerevenueRevenueofaCompetitiveFirmMarginalrevenueisthechangeintotalrevenuefromanadditionalunitsold.MR=dTR/dQ=PForcompetitivefirms,marginalrevenueequalsthepriceofthegood.RevenueofaCompetitiveFirmAR=TR/Q=P·Q/Q=PMR=dTR/dQ=P结论：平均收益、边际收益和需求曲线三线重合为一条水平线。QpTotal,Average,andMarginalRevenueforaCompetitiveFirmQuantity(Q)Price(P)TotalRevenue(TR=PxQ)AverageRevenue(AR=TR/Q)MarginalRevenue(MR=)1$6.00$6.00$6.002$6.00$12.00$6.00$6.003$6.00$18.00$6.00$6.004$6.00$24.00$6.00$6.005$6.00$30.00$6.00$6.006$6.00$36.00$6.00$6.007$6.00$42.00$6.00$6.008$6.00$48.00$6.00$6.00QTRDD/ProfitMaximizationfortheCompetitiveFirmThegoalofacompetitivefirmistomaximizeprofit.Thismeansthatthefirmwillwanttoproducethequantitythatmaximizesthedifferencebetweentotalrevenueandtotalcost.ProfitMaximization:ANumericalExamplePrice(P)Quantity(Q)TotalRevenue(TR=PxQ)TotalCost(TC)Profit(TR-TC)MarginalRevenue(MR=)MarginalCostMC=0$0.00$3.00-$3.00$6.001$6.00$5.00$1.00$6.00$2.00$6.002$12.00$8.00$4.00$6.00$3.00$6.003$18.00$12.00$6.00$6.00$4.00$6.004$24.00$17.00$7.00$6.00$5.00$6.005$30.00$23.00$7.00$6.00$6.00$6.006$36.00$30.00$6.00$6.00$7.00$6.007$42.00$38.00$4.00$6.00$8.00$6.008$48.00$47.00$1.00$6.00$9.00QTRDD/QTCDD/P=AR=MRProfitMaximizationfortheCompetitiveFirm...CostsandRevenueACMRQ*QMCProfitMaximizationfortheCompetitiveFirmProfitmaximizationoccursatthequantitywheremarginalrevenueequalsmarginalcost.WhenMR=MC，Profitismaximized.P=MR,P=MCTheFirm’sShort-RunDecisiontoShutDownAshutdownreferstoashort-rundecisionnottoproduceanythingduringaspecificperiodoftimebecauseofcurrentmarketconditions.Exitreferstoalong-rundecisiontoleavethemarket.TheFirm’sShort-RunDecisiontoShutDownThefirmconsidersitssunkcostswhendecidingtoexit,butignoresthemwhendecidingwhethertoshutdown.Sunkcostsarecoststhathavealreadybeencommittedandcannotberecovered.TheFirm’sShort-RunDecisiontoShutDownThefirmshutsdowniftherevenueitgetsfromproducingislessthanthevariablecostofproduction.ShutdownifTRVCShutdownifTR/QVC/QShutdownifPAVC26a.P1AC(ATC)P1P2P3ACAVCMCIfPATC,keepproducingataprofit.TheFirm’sShort-RunDecisiontoShutDown...QuantityATCAVC0CostsMCIfPAVC,keepproducingintheshortrun.IfPATC,keepproducingataprofit.Firm’sshort-runsupplycurve.b.P2AC,AVCACAVCP1P2P3IfPAVC,keepproducingintheshortrun.29c.IfP3AVC0,shutdown.ACAVCP1P2P3TheFirm’sShort-RunDecisiontoShutDownTheportionofthemarginal-costcurvethatliesaboveaveragevariablecostisthecompetitivefirm’sshort-runsupplycurve.TheMarginal-CostCurveandtheFirm’sSupplyDecision...CostsandRevenueThissectionofthefirm’sMCcurveisalsothefirm’ssupplycurve.MCACP=MR=AROQTheFirm’sLong-RunDecisiontoExitorEnteraMarketInthelong-run,thefirmexitsiftherevenueitwouldgetfromproducingislessthanitstotalcost.ExitifTRTCExitifTR/QTC/QExitifPATCTheFirm’sLong-RunDecisiontoExitorEnteraMarketAfirmwillentertheindustryifsuchanactionwouldbeprofitable.Enteri