MBA管理经济学.ppt

Chapter11ManagerialDecisionsinCompetitiveMarkets LearningObjectives Discuss3characteristicsofperfectlycompetitivemarketsExplainwhythedemandcurvefacingaperfectlycompetitivefirmisperfectlyelasticandservesasthefirm smarginalrevenuecurveFindshort runprofit maximizingoutput derivefirmandindustrysupplycurves andidentifyproducersurplusExplaincharacteristicsoflong runcompetitiveequilibriumforafirm derivelong runindustrysupply andidentifyeconomicrentandproducersurplusFindtheprofit maximizinglevelofavariableinputEmployempiricallyestimatedvaluesofmarketprice averagevariablecost andmarginalcosttocalculateprofit maximizingoutputandprofit PerfectCompetition Firmsareprice takersEachproducesonlyaverysmallportionoftotalmarketorindustryoutputAllfirmsproduceahomogeneousproductEntryinto exitfromthemarketisunrestricted DemandforaCompetitivePrice Taker Demandcurveishorizontalatpricedeterminedbyintersectionofmarketdemand supplyPerfectlyelasticMarginalrevenueequalspriceDemandcurveisalsomarginalrevenuecurve D MR CansellalltheywantatthemarketpriceEachadditionalunitofsalesaddstototalrevenueanamountequaltoprice DemandforaCompetitivePrice TakingFirm Figure11 2 D S Quantity Price dollars Quantity Price dollars PanelA Market PanelB Demandcurvefacingaprice taker 0 0 Profit MaximizationintheShortRun Intheshortrun managersmustmaketwodecisions Produceorshutdown Ifshutdown producenooutputandhiresnovariableinputsIfshutdown firmlosesamountequaltoTFCIfproduce whatistheoptimaloutputlevel Iffirmdoesproduce thenhowmuch Produceamountthatmaximizeseconomicprofit Profit TR TC Intheshortrun thefirmincurscoststhatare UnavoidableandmustbepaidevenifoutputiszeroVariablecoststhatareavoidableifthefirmchoosestoshutdownInmakingthedecisiontoproduceorshutdown thefirmconsidersonlythe avoidable variablecosts ignoresfixedcosts Profit MaximizationintheShortRun ProfitMargin orAverageProfit Levelofoutputthatmaximizestotalprofitoccursatahigherlevelthantheoutputthatmaximizesprofitmargin averageprofit Managersshouldignoreprofitmargin averageprofit whenmakingoptimaldecisions Short RunOutputDecision FirmwillproduceoutputwhereP SMCaslongas Totalrevenue totalavoidablecostortotalvariablecost TR TVC Equivalently thefirmshouldproduceifP AVC Short RunOutputDecision Thefirmwillshutdownif Totalrevenuecannotcovertotalavoidablecost TR TVC or equivalently P AVCProducezerooutputLoseonlytotalfixedcostsShutdownpriceisminimumAVC Fixed Sunk AverageCosts Fixed sunk averagecostsareirrelevantintheproductiondecisionFixedcostshavenoeffectonmarginalcostorminimumaveragevariablecost thusoptimallevelofoutputisunaffectedSunkcostsareforeverunrecoverableandcannotaffectcurrentorfuturedecisionsOnlymarginalcosts notaveragecosts matterfortheoptimallevelofoutput ProfitMaximization P 36 Figure11 3 ProfitMaximization P 36 Figure11 3 PanelA Totalrevenue totalcost PanelB ProfitcurvewhenP 36 ProfitMaximization P 36 Figure11 4 Break evenpoint Break evenpoint Short RunLossMinimization P 10 50 Figure11 5 Totalrevenue 10 50 x300 3 150 Profit 3 150 5 100 1 950 SummaryofShort RunOutputDecision AVCtellswhethertoproduceShutdownifpricefallsbelowminimumAVCSMCtellshowmuchtoproduceIfP minimumAVC produceoutputatwhichP SMCATCtellshowmuchprofit lossifproduce P ATC Q Short RunSupplyCurves Foranindividualprice takingfirmPortionoffirm smarginalcostcurveaboveminimumAVCForpricesbelowminimumAVC quantitysuppliediszeroForacompetitiveindustryHorizontalsumofsupplycurvesofallindividualfirms alwaysupwardslopingSupplypricesgivemarginalcostsofproductionforeveryfirm Short RunProducerSurplus Short runproducersurplusistheamountbywhichTRexceedsTVCTheareaabovetheshort runsupplycurvethatisbelowmarketpriceovertherangeofoutputsuppliedExceedseconomicprofitbytheamountofTFC ComputingShort RunProducerSurplus Figure11 6 Short RunFirm IndustrySupply Figure11 6 Long RunProfit MaximizingEquilibrium Figure11 7 Profit 17 12 x240 1 200 Long RunCompetitiveEquilibrium Allfirmsareinprofit maximizingequilibrium P LMC Occursbecauseofentry exitoffirmsin outofindustryMarketadjustssoP LMC LAC Long RunCompetitiveEquilibrium Figure11 8 Long RunIndustrySupply Long runindustrysupplycurvecanbeflat perfectlyelastic orupwardslopingDependsonwhetherconstantcostindustryorincreasingcostindustryEconomicprofitiszeroforallpointsonthelong runindustrysupplycurveforbothtypesofindustries ConstantcostindustryAsindustryoutputexpands inputpricesremainconstant minimumLACisunchangedP minimumLAC socurveishorizontal perfectlyelastic IncreasingcostindustryAsindustryoutputexpands inputpricesrise minimumLACrisesLong runsupplypricerises curveisupwardsloping Long RunIndustrySupply Long RunIndustrySupplyforaConstantCostIndustry Figure11 9 Long RunIndustrySupplyforanIncreasingCostIndustry Figure11 10 Firm soutput EconomicRent Paymenttotheownerofascarce superiorresourceinexcessoftheresource sopportunitycostInlong runcompetitiveequilibriumfirmsthatemploysuchresourcesearnzeroeconomicprofitPotentialeconomicprofitispaidtotheresourceaseconomicrentInincreasingcostindustries alllong runproducersurplusispaidtoresourcesuppliersaseconomicrent EconomicRentinLong RunCompetitiveEquilibrium Figure11 11 Profit MaximizingInputUsage Profit maximizinglevelofinputusageproducesexactlythatlevelofoutputthatmaximizesprofit Marginalrevenueproduct MRP MRPofanadditionalunitofavariableinputistheadditionalrevenuefromhiringonemoreunitoftheinput Ifchoosetoproduce IftheMRPofanadditionalunitofinputisgreaterthanthepriceofinput thatunitshouldbehiredEmployamountofinputwhereMRP inputprice Profit MaximizingInputUsage Averagerevenueproduct ARP Averagerevenueperworker ShutdowninshortrunifARP MRPWhenARP MRP TR TVC Profit MaximizingInputUsage Profit MaximizingLaborUsage Figure11 12 ImplementingtheProfit MaximizingOutputDecision Step1 ForecastproductpriceUsestatisticaltechniquesfromChapter7Step2 EstimateAVC SMCAVC a bQ cQ2SMC a 2bQ 3cQ2 Step3 CheckshutdownruleIfP AVCminthenproduceIfP AVCminthenshutdownTofindAVCminsubstituteQminintoAVCequation ImplementingtheProfit MaximizingOutputDecision Step4 IfP AVCmin findoutputwhereP SMCSetforecastedpriceequaltoestimatedmarginalcost solveforQ ImplementingtheProfit MaximizingOutputDecision P a 2bQ 3cQ 2 Step5 ComputeprofitorlossProfit TR TC PxQ AVCxQ TFC P AVC Q TFC IfP AVCmin firmshutsdown profitis TFC ImplementingtheProfit MaximizingOutputDecision Profit LossatBeauApparel Figure11 13 Profit LossatBeauApparel Figure11 13 Summary Perfectcompetitorsareprice takers producehomogenousoutput andhavenobarrierstoentryThedemandcurveforaperfectlycompetitivefirmisperfectlyelastic orhorizontal atthemarketdeterminedequilibriumprice andmarginalrevenueequalsp