英文9--完全竞争.ppt

Marketstructure Whatismarket Howtodividethemarket Thebuyers quantityandscaleThesellers quantityandscaleTheproductEntrybarrieAnyforcethatpreventsfirmsfromenteringanewmarketExamples monopolyoverinputs largefixedinvestment distributionnetwork legalentrybarriers copyrights patent illegal anti competitivepracticesInformation FourMarketstructures PerfectlycompetitivemarketMonopolisticcompetitionoligopolymonopoly Competitiveintensity Competitiveintensity Competitiveintensitydependsmoreonthenatureofcompetitionthanthenumberofcompetitors Competitionismostintensewhenfirmscompeteonprice Themoreintensecompetitionis thelowerisfirmprofitability 市场结构 5 Marketstructureoverview 6 市场结构及其特征表 TheMeaningofCompetition Aperfectlycompetitivemarkethasthefollowingcharacteristics Therearemanybuyersandsellersinthemarket Thegoodsofferedbythevarioussellersarelargelythesame Firmscanfreelyenterorexitthemarket perfectcompetitivemarket CompetitiveMarket 4characteristicsofperfectcompetitivemarket P154 TheMeaningofCompetition Asaresultofitscharacteristics theperfectlycompetitivemarkethasthefollowingoutcomes Theactionsofanysinglebuyerorsellerinthemarkethaveanegligibleimpactonthemarketprice Eachbuyerandsellertakesthemarketpriceasgiven TheMeaningofCompetition Buyersandsellersincompetitivemarketsaresaidtobepricetakers Buyersandsellersmustacceptthepricedeterminedbythemarket p 12 Demandcurve Lawofdemand D D S RevenueofaCompetitiveFirm Totalrevenueforafirmisthesellingpricetimesthequantitysold TR PXQ Totalrevenueisproportionaltotheamountofoutput RevenueofaCompetitiveFirm Averagerevenuetellsushowmuchrevenueafirmreceivesforthetypicalunitsold RevenueofaCompetitiveFirm Inperfectcompetition averagerevenueequalsthepriceofthegood RevenueofaCompetitiveFirm Marginalrevenueisthechangeintotalrevenuefromanadditionalunitsold MR dTR dQ P Forcompetitivefirms marginalrevenueequalsthepriceofthegood RevenueofaCompetitiveFirm AR 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 p Total Average andMarginalRevenueforaCompetitiveFirm ProfitMaximizationfortheCompetitiveFirm Thegoalofacompetitivefirmistomaximizeprofit Thismeansthatthefirmwillwanttoproducethequantitythatmaximizesthedifferencebetweentotalrevenueandtotalcost ProfitMaximization ANumericalExample P AR MR ProfitMaximizationfortheCompetitiveFirm ProfitMaximizationfortheCompetitiveFirm Profitmaximizationoccursatthequantitywheremarginalrevenueequalsmarginalcost WhenMR MC Profitismaximized P MR P MC TheFirm sShort RunDecisiontoShutDown Ashutdownreferstoashort rundecisionnottoproduceanythingduringaspecificperiodoftimebecauseofcurrentmarketconditions Exitreferstoalong rundecisiontoleavethemarket TheFirm sShort RunDecisiontoShutDown Thefirmconsidersitssunkcostswhendecidingtoexit butignoresthemwhendecidingwhethertoshutdown Sunkcostsarecoststhathavealreadybeencommittedandcannotberecovered TheFirm sShort RunDecisiontoShutDown Thefirmshutsdowniftherevenueitgetsfromproducingislessthanthevariablecostofproduction ShutdownifTR VCShutdownifTR Q VC QShutdownifP AVC 26 a P1 AC ATC IfP ATC keepproducingataprofit TheFirm sShort RunDecisiontoShutDown Quantity ATC AVC 0 Costs b P2AVC IfP AVC keepproducingintheshortrun 29 c IfP3 AVC0 shutdown TheFirm sShort RunDecisiontoShutDown Theportionofthemarginal costcurvethatliesaboveaveragevariablecostisthecompetitivefirm sshort runsupplycurve TheMarginal CostCurveandtheFirm sSupplyDecision Thissectionofthefirm sMCcurveisalsothefirm ssupplycurve TheFirm sLong RunDecisiontoExitorEnteraMarket Inthelong run thefirmexitsiftherevenueitwouldgetfromproducingislessthanitstotalcost ExitifTR TCExitifTR Q TC QExitifP ATC TheFirm sLong RunDecisiontoExitorEnteraMarket Afirmwillentertheindustryifsuchanactionwouldbeprofitable EnterifTR TCEnterifTR Q TC QEnterifP ATC TheCompetitiveFirm sLong RunSupplyCurve Quantity MC Long runS ATC AVC 0 Costs TheCompetitiveFirm sLong RunSupplyCurve Thecompetitivefirm slong runsupplycurveistheportionofitsmarginal costcurvethatliesaboveaveragetotalcost TheFirm sShort RunandLong RunSupplyCurves Short RunSupplyCurveTheportionofitsmarginalcostcurvethatliesaboveaveragevariablecost Long RunSupplyCurveThemarginalcostcurveabovetheminimumpointofitsaveragetotalcostcurve MeasuringProfitintheGraphfortheCompetitiveFirm Quantity 0 Price P AR MR ATC MC P Profit maximizingquantity a AFirmwithProfits MeasuringProfitintheGraphfortheCompetitiveFirm Quantity 0 Price P AR MR ATC MC P Q Loss minimizingquantity b AFirmwithLosses SupplyinaCompetitiveMarket Marketsupplyequalsthesumofthequantitiessuppliedbytheindividualfirmsinthemarket TheShortRun MarketSupplywithaFixedNumberofFirms Foranygivenprice eachfirmsuppliesaquantityofoutputsothatitsmarginalcostequalsprice Themarketsupplycurvereflectstheindividualfirms marginalcostcurves TheShortRun MarketSupplywithaFixedNumberofFirms a IndividualFirmSupply Quantity firm 0 Price b MarketSupply Quantity market Price 0 Supply MC 1 00 2 00 100 200 1 00 2 00 100 000 200 000 TheLongRun MarketSupplywithEntryandExit Firmswillenterorexitthemarketuntilprofitisdriventozero Inthelongrun priceequalstheminimumofaveragetotalcost Thelong runmarketsupplycurveishorizontalatthisprice TheLongRun MarketSupplywithEntryandExit a Firm sZero ProfitCondition Quantity firm 0 Price P minimumATC b MarketSupply Quantity market Price 0 Supply MC ATC TheLongRun MarketSupplywithEntryandExit Attheendoftheprocessofentryandexit firmsthatremainmustbemakingzeroeconomicprofit Theprocessofentry exitendsonlywhenpriceandaveragetotalcostaredriventoequality Long runequilibriummusthavefirmsoperatingattheirefficientscale FirmsStayinBusinesswithZeroProfit Profitequalstotalrevenueminustotalcost Totalcostincludesalltheopportunitycostsofthefirm Inthezero profitequilibrium thefirm srevenuecompensatestheownersforthetimeandmoneytheyexpendtokeepthebusinessgoing IncreaseinDemandintheShortRun Anincreaseindemandraisespriceandquantityintheshortrun Firmsearnprofitsbecausepricenowexceedsaveragetotalcost IncreaseinDemandintheShortRun Market Firm Quantity firm 0 Price MC ATC P1 Quantity market Price 0 D1 P1 Q1 A S 1 Long runsupply a InitialCondition P IncreaseinDemandintheShortRun Market Firm Quantity firm 0 Price MC ATC P1 Quantity market Price 0 D1 P1 Q1 A S1 Long runsupply b Short RunResponse IncreaseinDemandintheShortRun Market Firm Quantity firm 0 Price MC ATC P1 Quantity market Price 0 D1 P1 Q1 A S1 Long runsupply c Long RunResponse D2 B Q2 P2 S2 C Q3 Summary Becauseacompetitivefirmisapricetaker itsrevenueisproportionaltotheamountofoutputitproduces Thepriceofthegoodequalsboththefirm saverag