管理经济学（原书第14版） 课件 第11章　竞争市场上的管理决策

Chapter11ManagerialDecisionsinCompetitiveMarketsMANAGERIALECONOMICSFoundationsofBusinessAnalysisandStrategyFourteenthEditionCHRISTOPHERR.THOMAS©McGrawHillLLC.Allrightsreserved.NoreproductionordistributionwithoutthepriorwrittenconsentofMcGrawHillLLC..LearningObjectives11.1Discussthreecharacteristicsofperfectlycompetitive markets.11.2Explainwhythedemandcurvefacingaperfectlycompetitivefirmisperfectlyelasticandservesasthefirm’smarginalrevenuecurve.11.3Findshort‐runprofit‐maximizingoutputandderivebothfirmandindustrysupplycurves.11.4Explaincharacteristicsoflong‐runcompetitiveequilibriumforafirmandderivelong‐runindustrysupplycurves.11.5Findtheprofit‐maximizinglevelofavariableinput.11.6Employempiricallyestimatedvaluesofmarketprice,averagevariablecost,andmarginalcosttocalculateprofit‐maximizingoutputandprofit.2PerfectCompetitionPerfectcompetitionisamarketstructurethatexistswhen:Firmsareprice-takers.Eachfirmproducesonlyaverysmallportionoftotalmarketorindustryoutput.Allfirmsproduceahomogeneousproduct.Entryintoandexitfromthemarketareunrestricted.3DemandforaPrice-TakingFirmDemandcurveisperfectlyelasticHorizontaldemandfacingasingle,price-takingfirminacompetitivemarket,atthepricedeterminedbyintersectionofmarketdemandandsupplyMarginalrevenueequalspriceDemandcurveisalsomarginalrevenuecurve,(D=MR).CansellalltheywantatthemarketpriceEachadditionalunitofsalesaddstototalrevenueanamountequaltoprice.4Figure11.1DemandandMarginalRevenueFacingaCitrusProducerAccessthetextalternativeforslideimages.5Figure11.2DerivationofDemandforaPrice-TakingFirmAccessthetextalternativeforslideimages.6ProfitMaximizationintheShortRunIntheshortrun,managersmustmaketwodecisions:Produceorshutdown?Ifshutdown,producenooutputandhirenovariableinputs.Ifshutdown,firmmuststillpayforsunkfixedinputcosts.Inmakingthedecisiontoproduceorshutdown,thefirmconsidersonlytheavoidablecostsandignoressunkcosts.2. Ifproduce,whatistheoptimaloutputlevel?Iffirmdoesproduce,thenhowmuch?Produceamountthatmaximizeseconomicprofit.EconomicProfit

=

π

=

TR−TC7ProfitMargin(orAverageProfit)Levelofoutputthatmaximizestotalprofitoccursatahigherlevelthantheoutputthatmaximizesprofitmargin(andaverageprofit).Averageprofitmeasuresprofitperunitandisequivalenttoprofitmarginwhenallunitssellforthesameprice.Managersshouldignoreprofitmargin(averageprofit)whenmakingoptimaldecisions.8Figure11.3MaximizingProfitintheShortRunAccessthetextalternativeforslideimages.9Short-RunOutputDecisionFirmwillproduceoutputwhereP=SMC

aslongas:Totalrevenue≥totalavoidablecostortotalvariablecost

(TR≥TVC).Equivalently,thefirmshouldproduceifP≥AVC.Thefirmwillshutdownif:Totalrevenuecannotcovertotalavoidablecost(TR<TVC)

or,equivalently,P

AVC.Producezerooutputandloseonlytotalsunkfixedcosts.ShutdownpriceisminimumAVC.Break-evenpointsareoutputlevelswhereP=ATCandprofitequalszero(PointsUandVinFigure11.4).10Figure11.4ProfitMaximizationWhenP=$36Accessthetextalternativeforslideimages.11Figure11.5CommonMistake:MaximizingProfitMargin(P−ATC)Accessthetextalternativeforslideimages.12Figure11.6LossMinimizationintheShortRunAccessthetextalternativeforslideimages.13Fixed,Sunk,andAverageCostsFixed,sunk,andaveragecostsareirrelevantintheproductiondecision.Fixedcostshavenoeffectonmarginalcostorminimumaveragevariablecost—thusoptimallevelofoutputisunaffected.Sunkcostsareforeverunrecoverableandcannotaffectcurrentorfuturedecisions.Onlymarginalcosts,notaveragecosts,matterfortheoptimallevelofoutput.14Table11.1TheIrrelevanceofFixedCosts(1)(2)(3)(4)(5)(6)(7)(8)TotalFixedCostsPriceOutputTotalRevenueTotalVariableCostsRevenueRemainingAfterPayingVariableCostsProfit(Loss)ifQ=300Profit(Loss)ifQ=0$200$10.50300$3,150$2,700$450$250$−2002,40010.503003,1502,700450-1,900-2,4003,00010.503003,1502,700450-2,550-3,00010,00010.503003,1502,700450-9,550-10,000100,00010,503003,1502,700450-99,550-100,00015SummaryofShort-RunOutputDecisionAVC

tellswhethertoproduce.ShutdownifpricefallsbelowminimumAVC.SMCtellshowmuchtoproduce.IfP

minimumAVC,producetheoutputatwhichP=SMC.ATCtellshowmuchprofit/lossifthefirmchoosestoproduce.

π=(P–ATC)Q16Short-RunSupplyCurvesForanindividualprice-takingfirm:Short-runsupplycurveistheportionoffirm’smarginalcostcurveaboveminimumAVC.ForpricesbelowminimumAVC,quantitysuppliediszero.Foracompetitiveindustry:Horizontalsumofsupplycurvesofallindividualfirms;alwaysupward-sloping.Supplypricesgivemarginalcostsofproductionforeveryfirm.17Figure11.7Short-RunFirmandIndustrySupplyAccessthetextalternativeforslideimages.18Figure11.8Profit-MaximizingEquilibriumintheLongRunAccessthetextalternativeforslideimages.19Long-RunCompetitiveEquilibriumLong-runcompetitiveequilibriumistheconditioninwhichallfirmsareproducingwhereP=LMCandeconomicprofitsarezero(P=LAC).Occursbecauseofentry/exitoffirmsin/outofindustry.MarketadjustssoP=LMC=LAC.20Figure11.9Long-RunEquilibriumforaFirminaCompetitiveIndustryAccessthetextalternativeforslideimages.21Long-RunIndustrySupplyLong-runindustrysupplycurvecanbeflat(perfectlyelastic)orupward-sloping.Dependsonwhetherconstantcostindustryorincreasingcostindustry.Economicprofitiszeroforallpointsonthelong-runindustrysupplycurveforbothtypesofindustries.Constantcostindustry:Asindustryoutputexpands,inputpricesremainconstant,andminimumLACisunchanged.P=minimumLAC,socurveishorizontal(perfectlyelastic).Increasingcostindustry:Asindustryoutputexpands,inputpricesrise,andminimumLACrises.Long-runsupplypricerises,andcurveisupward-sloping.22Figure11.10Long-RunIndustrySupplyforaConstantCostIndustryAccessthetextalternativeforslideimages.23Figure11.11Long-RunIndustrySupplyforanIncreasingCostIndustryAccessthetextalternativeforslideimages.24Profit-MaximizingInputUsageMarginalrevenueproduct(MRP)

istheadditionalrevenueearnedwhenthefirmhiresonemoreunitoftheinput.Ifchoosetoproduce:IftheMRP

ofanadditionalunitofinputisgreaterthanthepriceofinput,thatunitshouldbehired.EmployamountofinputwhereMRP

=inputprice=w.Profit-maximizinglevelofinputusageproducesexactlythatlevelofoutputthatmaximizesprofit.25AverageRevenueProductandtheShutdownDecisionAveragerevenueproduct(ARP)

istheaveragerevenueperworker:ShutdowninshortrunifARP<MRPWhenARP<MRP,TR<TVC.26Figure11.12Profit-MaximizingInputUsageAccessthetextalternativeforslideimages.27ImplementingtheProfit-MaximizingOutputDecision(Steps1and2)GeneralrulesforimplementationShouldthefirmproduceorshutdown?Ifproduce,howmuchshouldthefirmproduce?Step1:ForecastproductpriceUsestatisticaltechniquesfromChapter7.Step2:EstimateAVC

andSMC••28ImplementingtheProfit-MaximizingOutputDecision(Step3)Step3:ChecktheshutdownruleIfthenproduce.Ifthenshutdown.TofindsubstituteintoAVCequation29ImplementingtheProfit-MaximizingOutputDecision(Step4)Step4:IffindoutputwhereP=SMCSetforecastedpriceequaltoestimatedmarginalcostandsolveforQ*.30ImplementingtheProfit-MaximizingOutputDecision(Step5)Step5:ComputationofprofitorlossProfit

=π=TR−TC=(PxQ*)−[(AVCxQ*)−TFC]=(P−AVC)Q*−TFCIffirmshutsdownandπ=−TFC.31Summary1Perfectcompetitorsareprice-takers,producehomogenousoutput,andhavenobarrierstoentry.Thedemandcurveforaperfectlycompetitivefirmisperfectlyelastic(orhorizontal)atthemarketdeterminedequilibriumprice,andmarginalrevenueequalsprice.Managersmaketwodecisionsintheshortrun:(1)produceorshutdownand(2)ifproduce,howmuchtoproduce.Whenpositiveprofitispossible,profitismaximizedattheoutputwhereP=SMC.WhenmarketpricefallsbelowminimumAVC,

thefirmshutsdownandproducesnothing,losingonlyTFC.32Summary2Inlong-runcompetitiveequilibrium,allfirmsareinprofit-maximizingequilibrium(P=LMC).Noincentiveforfirmstoenterorexittheindustrybecauseeconomicprofitiszero(P=LAC).Choosingeitheroutputorinputusageleadstothesameoptimaloutputdecisionandprofitlevel.Fivestepstofindtheprofit-maximizingrateofproductionandthelevelofprofitforacompetitivefirm:Forecastthepriceoftheproduct.Estimateaveragevariablecostandmarginalcost.Checktheshutdownrule.IffindtheoutputlevelwhereP=SMC.Computeprofitorloss.33EndofMainContent©McGrawHillLLC.Allrightsreserved.NoreproductionordistributionwithoutthepriorwrittenconsentofMcGrawHillLLC.AccessibilityContent:TextAlternativesforImages35Figure11.1DemandandMarginalRevenueFacingaCitrusProducer

-TextAlternativeReturntoparent-slidecontainingimages.Theverticalaxisislabeledasthepriceindollarsperpound.Thehorizontalaxisislabeledasquantityinpounds.AhorizontallinelabeledDequalsMPequalsP,beginsatapoint(0,1.75),andextendsrightward.Twodotsareplottedonthelineat(50,000,1.75)and(500,000,1.75).Twoverticaldashedlinesconnectdotsonthelinewith(50,000,0)and(500,000,0).Notethatalltheabove-mentionedvaluesareapproximate.Returntoparent-slidecontainingimages.36Figure11.2DerivationofDemandforaPrice-TakingFirm

-TextAlternativeReturntoparent-slidecontainingimages.ThefirstgraphistitledPanelA-Market.Theverticalaxisislabeledaspriceindollars.Thehorizontalaxisislabeledasquantityinpounds.AdecreasingdiagonallineandanincreasingdiagonallinelabeledDandS,intersecteachotherat(Qnaught,Pnaught).Notethatalltheabove-mentionedvaluesareapproximate.Ahorizontaldashedlinebeginsat(0,Pnaught)andpassesthroughtheintersectionpoint.Averticaldashedsegmentbeginsat(Qnaught,0)andmeetstheintersectionpoint.ThesecondgraphistitledPanelB-demandcurvefacingapricetaker.Theverticalaxisislabeledaspriceindollars.Thehorizontalaxisislabeledasquantityinpounds.AhorizontallinelabeledDequalsMR,beginsat(0,Pnaught)andextendsrightward.Notethatalltheabove-mentionedvaluesareapproximate.Returntoparent-slidecontainingimages.37Figure11.3MaximizingProfitintheShortRun

-TextAlternativeReturntoparent-slidecontainingimages.Theverticalaxisislabeledpriceandcostindollarsperunit.Thehorizontalaxisislabeledoutputintheshortrun(q).AhorizontallinelabeledDcolonMRequalsPequals36dollars,beginsat(0,36)andextendsrightward.AconcaveupwardcurvelabeledATCentersfromthetop,intersectsthehorizontallineatpoint(100,36)labeledu,fallslefttotheright,reachesalowpoint(400,16)labeledN,thenrisesthroughthepoints(600,19)labeledBand(950,36)labeledv.AnotherconcaveupwardcurvelabeledSMC,beginsat(1,14),fallslefttotheright,throughthepoint(100,8),reachesalowpoint,thenrisesthroughthepoints(300,9.5),(400,16)labeledNand(600,36)labeledA.AdashedconcaveupwardcurvelabeledAVCbeginsneartheverticalaxisandpassesthrough(100,13),(300,9.5),and(600,15)labeledC.Arectangularportionbelowthelinehasitsverticesrat(0,36),Aat(600,36),Bat(600,19),andtat(0,19),whichisshadedandlabeledasprofitequals10,200dollars.Notethatallthevaluesmentionedaboveareapproximate.Returntoparent-slidecontainingimages.38Figure11.4ProfitMaximizationWhenP=$36-TextAlternativeReturntoparent-slidecontainingimages.ThefirstgraphistitledTotalRevenueandtotalcost.Theverticalaxisislabeledastotalrevenueandcostindollarsandrangesfrom0to34,200.Thehorizontalaxisislabeledasquantityandrangesfrom0to950.AlinelabeledTR(Pequals36dollars)hasanincreasingslope,beginsattheorigin,passesthroughpointsUat(100,2,500),pointJat(600,21,600),andpointVat(950,34,200).Aconcave-upincreasingcurve,labeledTC,startsatthe(0,2,400)andintersectslineTRatapointlabeledU,risesfromthelefttotheright,passesthroughpointKat(600,11,400)andpointVat(950,34,200).ThepointsUandVarelabeledasbreak-evenpoints.AtangentTTprimeisdrawnonthecurveatpointK.Theslopeofthetangentandthelineisthesamewhichisshownbyasmallrighttriangledrawnonthemshowing1runand36rise.ThesecondgraphistitledpanelB-theprofitcurvewhenthepriceis36dollars.Thesecondgraphistitledtheprofitcurvewhenthepriceis36dollars.Theverticalaxisislabeledasprofitindollarsandrangesfromnegative2,400to10,200.Thehorizontalaxisislabeledasquantityandrangesfrom0to950.Thecurvelabeledpibeginsat(0,negative2,400),riseslinearlyfromlefttotheright,intersectsthex-axisonpointUprimeat(100,0),thenbecomesconcave-downandpassesthrough(400,8,000),pointAprimeat(600,10,200),thenfallslefttotheright,intersectsthex-axisatpointVprimeat(950,0).AtangentlinebetweenTandTprimepassesthroughthepointUprimeat(100,0).Arighttriangleisformedherewithabaseof1andaheightof28.Notethatthevaluesmentionedaboveareapproximate.Returntoparent-slidecontainingimages.39Figure11.5CommonMistake:MaximizingProfitMargin(P−ATC)-TextAlternativeReturntoparent-slidecontainingimages.Theverticalaxisislabeledpriceandcostindollarsperunit.Thehorizontalaxisislabeledoutputintheshortrun(q).AhorizontallinelabeledDcolonMRequalsPequals36dollars,beginsat(0,36)andextendsrightward.AconcaveupwardcurvelabeledATCentersfromthetop,intersectsthehorizontallineatpoint(100,36)labeledu,fallslefttotheright,reachesalowpoint(400,16)labeledN,thenrisesthroughthepoints(600,19)labeledBandextendsattheright.AnotherconcaveupwardcurvelabeledSMCbeginsat(1,14),fallslefttotheright,throughthepoint(100,8),reachesalowpoint,thenrisesthroughthepoints(300,9.5),(400,16)labeledNand(600,36)labeledA.Arectangularportionbelowthelinehasitsverticesrat(0,36),Fat(400,36),Nat(400,16),andsat(0,16),isshadedandlabeledasprofitequals8,000dollars.TheadjacenttriangularregionAFNisshadedandlabeledaslostprofitequals2,200dollars.ThedistancebetweenFNislabeledasprofitmarginequals20dollars.Notethatallthevaluesmentionedaboveareapproximate.Returntoparent-slidecontainingimages.40Figure11.6LossMinimizationintheShortRun-TextAlternativeReturntoparent-slidecontainingimages.Theverticalaxisislabeledpriceandcostindollarsperunit.Thehorizontalaxisislabeledoutputintheshortrun(q).AhorizontallinelabeledDcolonMRequalsPequals11dollars,beginsat(0,11)andextendsrightward.AconcaveupwardcurvelabeledATCentersfromthetop,fallsfromlefttoright,passesthroughapointHat(340,16.66),reachesalowpointslightlyrighttopointH,andthenrisestotheright.AnothercurvelabeledSMCbeginsneartheorigin,fallsfromlefttoright,reachesalowpoint,thenriseslinearlytotheright,passesthroughpointIat(340,11),andpointsNonthecurve.AdashedconcaveupwardcurvelabeledAVC,beginsnearandbelowthehorizontalaxisapproximatelyat(160,10.5),andpassesthroughpointS,pointJat(340,9.50),risestotherightthroughthehorizontalline.PointJdenotes9.60dollars.Arectangularregionhasitsverticesat(0,16.66),(340,16.66),(340,11),and(0,11)anditisshadedandlabeledasprofit(loss)equalsnegative1,924dollars.Notethatallthevaluesmentionedaboveareapproximate.Returntoparent-slidecontainingimages.41Figure11.7Short-RunFirmandIndustrySupply-TextAlternativeReturntoparent-slidecontainingimages.ThefirstgraphistitledPanelA-supplycurveforthefirm.Theverticalaxisislabeledpriceandcostindollars.ThehorizontalaxisislabeledastheFirm'soutputq.AparaboliccurvelabeledSMCequalsS,beginsat(0,9),fallslefttotheright,reachesalowpointat(60,4),thenrisestotherightthroughthepoints'a'at(80,5),bat(107,9),andcat(120,12).Theportionofthecurvebetweentheoriginto(80,0)isdashed.AnothercurvelabeledAVCbeginsat(0,9),concaveup,fallslefttotheright,reachespoint'a'at(80,5),thenrisestotheright.ThesecondgraphistitledPanel-Bshort-runindustrysupplycurve(100firmswithidenticalcosts).Theverticalaxisislabeledpriceoutputandthehorizontalaxisislabeledindustryoutput(Qequalsnq).ThecurvelabeledSsubscriptSR,beginsat(0,5)andextendshorizontallytopointAat(8,000,5)thenriseslefttorightthroughpointBat(10,700,9)andpointCat(12,000,12).Notethatthevaluesmentionedaboveareapproximate.Returntoparent-slidecontainingimages.42Figure11.8Profit-MaximizingEquilibriumintheLongRun-TextAlternativeReturntoparent-slidecontainingimages.Theverticalaxisislabeledpriceandcostindollars.Thehorizontalaxisislabeledquantity.AhorizontallinelabeledDequalsMRequals17,beginsat(0,17)andextendsrightward.AconcaveupwardcurvelabeledLACentersfromthetopneartheverticalaxis,intersectsthehorizontallineatpointBat(20,17),fallslefttotheright,reachesalowpointMat(140,10),thenrisesthroughthepointsR(240,12)andpointBprimeat(290,17)thenextendstopright.AnotherconcaveupwardcurvelabeledLMCbeginsat(30,8),riseslefttotheright,throughpointMat(140,10),andpointSat(240,17).ArectangularportionbelowthelinehasitsverticesTat(0,17),Sat(240,17),Rat(240,12),andUat(0,12),whichisshaded.Notethatthevaluesmentionedaboveareapproximate.Returntoparent-slidecontainingimages.43Figure11.9Long-RunEquilibriumforaFirminaCompetitiveIndustry-TextAlternativeReturntoparent-slidecontainingimages.Theverticalaxisislabeledpriceandcostindollars.Thehorizontalaxisislabeledquantity.AhorizontallinelabeledDequalsMRequals10,beginsat(0,10)andextendsrightward.AconcaveupwardcurvelabeledLACentersfromthetopneartheverticalaxisabovethehorizontalline,fallslefttotheright,touchesthelineMRatitslowerpointMat(140,10),andthenrisestowardsthetopright.AnotherconcaveupwardcurvelabeledLMCbeginsat(30,8),riseslefttotheright,throughpointMat(140,10),andextendstopright.AnothercurvelabeledSMCbeginsneartheorigin,concaveup,passesthroughpointM,andextendsupwardtoacertainpoint.AnothercurvelabeledATCissimilartothefirstcurve,concaveupward,andpassesthroughpointM.Notethatthevaluesmentionedaboveareapproximate.Returntoparent-slidecontainingimages.44Figure11.10Long-RunIndustrySupplyforaConstantCostIndustry-TextAlternativeReturntoparent-slidecontainingimages.ThefirstgraphistitledPanelA,atypicalfirminlong-runequilibrium.Theverticalaxisislabeledpriceandcostindollars.ThehorizontalaxisislabeledFirm'soutput,q.AparaboliccurvelabeledLACopensupward,beginsnearthey-axis,hasitslowpointMat(140,10),andthenrisestotheright.ThesecondgraphistitledPanelB,Theindustryinlong-runequilibrium.Theverticalaxisislabeledpriceandcostindollarsandthehorizontalaxisislabeledindustryoutput(Qequalsnq).AhorizontallinelabeledSsubscriptLRequalsLACsubscriptmin,beginsat(0,10)andextendsrightward.ThreedecliningparallellinesegmentsintersectthehorizontallineatpointsAat(28,000,10),Bat(105,000,10),andCat(140,000,10).ThefirstlinethroughpointAislabeledasDsubscriptA,andthevalueatpointAshowsnequals200.ThesecondlinethroughpointBislabeledasDsubscriptB,andthevalueatpointBshowsnequals750.ThethirdlinethroughpointCislabeledasDsubscriptC,andthevalueatpointcshowsnequals1,000.Returntoparent-slidecontainingimages.45Figure11.11Long-RunIndustrySupplyforanIncreasingCostIndustry-TextAlternativeReturntop