第14章-竞争市场上企业-曼昆经济学原理第七版

第14章-竞争市场上企业-曼昆经济学原理第七版第一页，共33页。WhatisaCompetitiveMarket?CompetitivemarketPerfectlycompetitivemarketMarketwithmanybuyersandsellersTradingidenticalproductsEachbuyerandsellerisapricetakerFirmscanfreelyenterorexitthemarket©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.2第二页，共33页。WhatisaCompetitiveMarket?FirminacompetitivemarketTriestomaximizeprofitProfitTotalrevenueminustotalcostTotalrevenue,TR=PˣQPricetimesquantityProportionaltotheamountofoutput©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.3第三页，共33页。WhatisaCompetitiveMarket?Averagerevenue,AR=TR/QTotalrevenuedividedbythequantitysoldMarginalrevenue,MR=∆TR/∆QChangeintotalrevenuefromanadditionalunitsoldForcompetitivefirmsAR=PMR=P©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.4第四页，共33页。Table15©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.Total,Average,andMarginalRevenueforaCompetitiveFirm第五页，共33页。ProfitMaximizationMaximizeprofitProducequantitywheretotalrevenueminustotalcostisgreatestComparemarginalrevenuewithmarginalcostIfMR>MC:increaseproductionIfMR<MC:decreaseproductionMaximizeprofitwhereMR=MC©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.6第六页，共33页。Table27©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.ProfitMaximization:ANumericalExample第七页，共33页。ProfitMaximizationThemarginal-costcurveandthefirm’ssupplydecisionMCcurveisupwardslopingATCcurveisU-shapedMCcurvecrossestheATCcurveattheminimumofATCcurveThepricelineishorizontal:P=AR=MR©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.8第八页，共33页。Figure19©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.ProfitMaximizationforaCompetitiveFirmCostsandRevenueThisfigureshowsthemarginal-costcurve(MC),theaverage-total-costcurve(ATC),andtheaverage-variable-costcurve(AVC).Italsoshowsthemarketprice(P),whichforacompetitivefirmequalsbothmarginalrevenue(MR)andaveragerevenue(AR).AtthequantityQ1,marginalrevenueMR1exceedsmarginalcostMC1,soraisingproductionincreasesprofit.AtthequantityQ2,marginalcostMC2isabovemarginalrevenueMR2,soreducingproductionincreasesprofit.Theprofit-maximizingquantityQMAXisfoundwherethehorizontallinerepresentingthepriceintersectsthemarginal-costcurve.Quantity0ATCAVCP=AR=MRP=MR1=MR2MCMC1MC2Q2Q1QMAXThefirmmaximizesprofitbyproducingthequantityatwhichmarginalcostequalsmarginalrevenue.第九页，共33页。ProfitMaximizationRulesforprofitmaximization:IfMR>MC,firmshouldincreaseoutputIfMC>MR,firmshoulddecreaseoutputIfMR=MC,profit-maximizinglevelofoutputMarginal-costcurveDeterminesthequantityofthegoodthefirmiswillingtosupplyatanypriceIsthesupplycurve©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.10第十页，共33页。Figure211©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.MarginalCostastheCompetitiveFirm’sSupplyCurvePriceAnincreaseinthepricefromP1toP2leadstoanincreaseinthefirm’sprofit-maximizingquantityfromQ1toQ2.Becausethemarginal-costcurveshowsthequantitysuppliedbythefirmatanygivenprice,itisthefirm’ssupplycurve.Quantity0ATCAVCMCP1P2Q2Q1第十一页，共33页。ProfitMaximizationShutdownShort-rundecisionnottoproduceanythingDuringaspecificperiodoftimeBecauseofcurrentmarketconditionsFirmstillhastopayfixedcostsExitLong-rundecisiontoleavethemarketFirmdoesn’thavetopayanycosts©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.12第十二页，共33页。ProfitMaximizationThefirm’sshort-rundecisiontoshutdownTR=totalrevenueVC=variablecostsFirm’sdecision:ShutdownifTR<VC(P<AVC)Competitivefirm’sshort-runsupplycurveTheportionofitsmarginal-costcurveThatliesaboveaveragevariablecost©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.13第十三页，共33页。Figure314©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.TheCompetitiveFirm’sShort-RunSupplyCurveCostsIntheshortrun,thecompetitivefirm’ssupplycurveisitsmarginal-costcurve(MC)aboveaveragevariablecost(AVC).Ifthepricefallsbelowaveragevariablecost,thefirmisbetteroffshuttingdowntemporarily.Quantity0ATCMCAVC1.Intheshortrun,thefirmproducesontheMCcurveifP>AVC,...2....butshutsdownifP<AVC.第十四页，共33页。ProfitMaximizationSunkcostAcostthathasalreadybeencommittedandcannotberecoveredShouldbeignoredwhenmakingdecisions“Don’tcryoverspiltmilk”“Letbygonesbebygones”Intheshortrun,fixedcostsaresunkcosts©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.15第十五页，共33页。Near-emptyrestaurants&off-seasonminiaturegolfRestaurant–stayopenforlunch?FixedcostsNotrelevantAresunkcostsinshortrunVariablecosts–relevantShutdownifrevenuefromlunch<variablecostsStayopenifrevenuefromlunch>variablecosts16©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.Stayingopencanbeprofitable,evenwithmanytablesempty.第十六页，共33页。Near-emptyrestaurants&off-seasonminiaturegolfOperatorofaminiature-golfcourseIgnorefixedcostsShutdownifRevenue<variablecostsStayopenifRevenue>variablecosts17©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.第十七页，共33页。ProfitMaximizationFirm’slong-rundecisionExitthemarketifTotalrevenue<totalcosts;TR<TCSameas:P<ATCEnterthemarketifTotalrevenue>totalcosts;TR>TCSameas:P>ATCCompetitivefirm’slong-runsupplycurveTheportionofitsmarginal-costcurvethatliesaboveaveragetotalcost©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.18第十八页，共33页。Figure419©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.TheCompetitiveFirm’sLong-RunSupplyCurveCostsInthelongrun,thecompetitivefirm’ssupplycurveisitsmarginal-costcurve(MC)aboveaveragetotalcost(ATC).Ifthepricefallsbelowaveragetotalcost,thefirmisbetteroffexitingthemarket.Quantity0MC1.Inthelongrun,thefirmproducesontheMCcurveifP>ATC,...2....butexitsifP<ATCATC第十九页，共33页。ProfitMaximizationMeasuringprofitIfP>ATCProfit=TR–TC=(P–ATC)ˣQIfP<ATCLoss=TC-TR=(ATC–P)ˣQ=Negativeprofit©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.20第二十页，共33页。Figure521©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.ProfitastheAreabetweenPriceandAverageTotalCostPriceTheareaoftheshadedboxbetweenpriceandaveragetotalcostrepresentsthefirm’sprofit.Theheightofthisboxispriceminusaveragetotalcost(P–ATC),andthewidthoftheboxisthequantityofoutput(Q).Inpanel(a),priceisaboveaveragetotalcost,sothefirmhaspositiveprofit.Inpanel(b),priceislessthanaveragetotalcost,sothefirmincursaloss.Quantity0(a)AfirmwithprofitsProfitMCATCP=AR=MRPQ(profit-maximizingquantity)ATCPriceQuantity0(b)AfirmwithlossesLossMCATCP=AR=MRPQ(loss-minimizingquantity)ATC第二十一页，共33页。SupplyCurveShortrun:marketsupplywithafixednumberoffirmsShortrun:numberoffirmsisfixedEachfirmsuppliesquantitywhereP=MCForP>AVC:supplycurveisMCcurveMarketsupplyAddupquantitysuppliedbyeachfirm©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.22第二十二页，共33页。Figure623©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.Short-RunMarketSupplyPriceIntheshortrun,thenumberoffirmsinthemarketisfixed.Asaresult,themarketsupplycurve,showninpanel(b),reflectstheindividualfirms’marginal-costcurves,showninpanel(a).Here,inamarketof1,000firms,thequantityofoutputsuppliedtothemarketis1,000timesthequantitysuppliedbyeachfirm.Quantity(firm)0(a)IndividualfirmsupplyMC100$2.00PriceQuantity(market)0(b)Marketsupply2001.00Supply100,000$2.00200,0001.00第二十三页，共33页。SupplyCurveLongrunFirmscanenterandexitthemarketIfP>ATC,firmsmakepositiveprofitNewfirmsenterthemarketIfP<ATC,firmsmakenegativeprofitFirmsexitthemarket©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.24第二十四页，共33页。SupplyCurveLongrunProcessofentryandexitendswhenFirmsstillinmarketmakezeroeconomicprofit(P=ATC)BecauseMC=ATC:EfficientscaleLongrunsupplycurveisperfectlyelasticHorizontalatminimumATC©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.25第二十五页，共33页。Figure726©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.Long-RunMarketSupplyPriceInthelongrun,firmswillenterorexitthemarketuntilprofitisdriventozero.Asaresult,priceequalstheminimumofaveragetotalcost,asshowninpanel(a).Thenumberoffirmsadjuststoensurethatalldemandissatisfiedatthisprice.Thelong-runmarketsupplycurveishorizontalatthisprice,asshowninpanel(b).Quantity(firm)0(a)Firm’sZero-ProfitConditionMCATCPriceQuantity(market)0(b)MarketsupplyP=minimumATCSupply第二十六页，共33页。SupplyCurveWhydocompetitivefirmsstayinbusinessiftheymakezeroprofit?Profit=totalrevenue–totalcostTotalcostincludesallopportunitycostsZero-profitequilibriumEconomicprofitiszeroAccountingprofitispositive©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.27“We’reanonprofitorganization-wedon’tintendtobe,butweare!”第二十七页，共33页。SupplyCurveMarketinlongrunequilibriumP=minimumATCZeroeconomicprofitIncreaseindemandDemandcurveshiftsoutwardShortrunHigherquantityHigherprice:P>ATC–positiveeconomicprofit©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.28第二十八页，共33页。SupplyCurvePositiveeconomicprofitinshortrunLongrun–firmsenterthemarketShortrunsupplycurve–shiftsrightPrice–decreasesbacktominimumATCQuantity–increasesBecausetherearemorefirmsinthemarketEfficientscale©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.29第二十九页，共33页。Figure830©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.AnIncreaseinDemandintheShortRunandLongRun(a)PricePriceThemarketstartsinalong-runequilibrium,shownaspointAinpanel(a).Inthisequilibrium,eachfirmmakeszeroprofit,andthepriceequalstheminimumaveragetotalcost.Quantity(market)0MarketQuantity(firm)0FirmATCMC(a)InitialConditionShort-runsupply,S1Demand,D1Q1P1Long-runsupplyP1A1.Amarketbeginsinlong-runequilibrium…2.…withthefirmearningzeroprofit.第三十页，共33页。Figure831©2015CengageLearning.