平狄克微观经济学课件(英文)08

Fernando&YvonnQuijanoPreparedby:ProfitMaximizationandCompetitiveSupply8CHAPTERCopyright©2009PearsonEducation,Inc.PublishingasPrenticeHall•Microeconomics•Pindyck/Rubinfeld,7e.Chapter8:ProfitMaximizationandCompetitiveSupply2of37Copyright©2009PearsonEducation,Inc.PublishingasPrenticeHall•Microeconomics•Pindyck/Rubinfeld,7e.CHAPTER8OUTLINE8.1PerfectlyCompetitiveMarkets8.2ProfitMaximization8.3MarginalRevenue,MarginalCost,andProfitMaximization8.4ChoosingOutputintheShortRun8.5TheCompetitiveFirm’sShort-RunSupplyCurve8.6TheShort-RunMarketSupplyCurve8.7ChoosingOutputintheLongRun8.8TheIndustry’sLong-RunSupplyCurveChapter8:ProfitMaximizationandCompetitiveSupply3of37Copyright©2009PearsonEducation,Inc.PublishingasPrenticeHall•Microeconomics•Pindyck/Rubinfeld,7e.PERFECTLYCOMPETITIVEMARKETS8.1Themodelofperfectcompetitionrestsonthreebasicassumptions:(1)pricetaking,(2)producthomogeneity,and(3)freeentryandexit.PriceTakingBecauseeachindividualfirmsellsasufficientlysmallproportionoftotalmarketoutput,itsdecisionshavenoimpactonmarketprice.●pricetakerFirmthathasnoinfluenceovermarketpriceandthustakesthepriceasgiven.ProductHomogeneityWhentheproductsofallofthefirmsinamarketareperfectlysubstitutablewithoneanother—thatis,whentheyarehomogeneous—nofirmcanraisethepriceofitsproductabovethepriceofotherfirmswithoutlosingmostorallofitsbusiness.Chapter8:ProfitMaximizationandCompetitiveSupply4of37Copyright©2009PearsonEducation,Inc.PublishingasPrenticeHall•Microeconomics•Pindyck/Rubinfeld,7e.PERFECTLYCOMPETITIVEMARKETS8.1FreeEntryandExit●freeentry(orexit)Conditionunderwhichtherearenospecialcoststhatmakeitdifficultforafirmtoenter(orexit)anindustry.WhenIsaMarketHighlyCompetitive?Becausefirmscanimplicitlyorexplicitlycolludeinsettingprices,thepresenceofmanyfirmsisnotsufficientforanindustrytoapproximateperfectcompetition.Conversely,thepresenceofonlyafewfirmsinamarketdoesnotruleoutcompetitivebehavior.Chapter8:ProfitMaximizationandCompetitiveSupply5of37Copyright©2009PearsonEducation,Inc.PublishingasPrenticeHall•Microeconomics•Pindyck/Rubinfeld,7e.PROFITMAXIMIZATION8.2DoFirmsMaximizeProfit?Theassumptionofprofitmaximizationisfrequentlyusedinmicroeconomicsbecauseitpredictsbusinessbehaviorreasonablyaccuratelyandavoidsunnecessaryanalyticalcomplications.Forsmallerfirmsmanagedbytheirowners,profitislikelytodominatealmostalldecisions.Inlargerfirms,however,managerswhomakeday-to-daydecisionsusuallyhavelittlecontactwiththeowners(i.e.thestockholders).Inanycase,firmsthatdonotcomeclosetomaximizingprofitarenotlikelytosurvive.Firmsthatdosurviveincompetitiveindustriesmakelong-runprofitmaximizationoneoftheirhighestpriorities.AlternativeFormsofOrganization●cooperativeAssociationofbusinessesorpeoplejointlyownedandoperatedbymembersformutualbenefit.Chapter8:ProfitMaximizationandCompetitiveSupply6of37Copyright©2009PearsonEducation,Inc.PublishingasPrenticeHall•Microeconomics•Pindyck/Rubinfeld,7e.PROFITMAXIMIZATION8.2Nationwide,condosareafarmorecommonthanco-ops,outnumberingthembyafactorofnearly10to1.Inthisregard,NewYorkCityisverydifferentfromtherestofthenation—co-opsaremorepopular,andoutnumbercondosbyafactorofabout4to1.WhataccountsfortherelativepopularityofhousingcooperativesinNewYorkCity?Partoftheanswerishistorical.HousingcooperativesareamucholderformoforganizationintheU.S.ThebuildingrestrictionsinNewYorkhavelongdisappeared,andyettheconversionofapartmentsfromco-opstocondoshasbeenrelativelyslow.Thetypicalcondominiumapartmentisworthabout15.5percentmorethanaequivalentapartmentheldintheformofaco-op.ItappearsthatinNewYork,manyownershavebeenwillingtoforgosubstantialamountsofmoneyinordertoachievenon-monetarybenefits.Chapter8:ProfitMaximizationandCompetitiveSupply7of37Copyright©2009PearsonEducation,Inc.PublishingasPrenticeHall•Microeconomics•Pindyck/Rubinfeld,7e.MARGINALREVENUE,MARGINALCOST,ANDPROFITMAXIMIZATION8.3●profitDifferencebetweentotalrevenueandtotalcost.π(q)=R(q)−C(q)●marginalrevenueChangeinrevenueresultingfromaone-unitincreaseinoutput.ProfitMaximizationintheShortRunFigure8.1Afirmchoosesoutputq*,sothatprofit,thedifferenceABbetweenrevenueRandcostC,ismaximized.Atthatoutput,marginalrevenue(theslopeoftherevenuecurve)isequaltomarginalcost(theslopeofthecostcurve).Δπ/Δq=ΔR/Δq−ΔC/Δq=0MR(q)=MC(q)Chapter8:ProfitMaximizationandCompetitiveSupply8of37Copyright©2009PearsonEducation,Inc.PublishingasPrenticeHall•Microeconomics•Pindyck/Rubinfeld,7e.MARGINALREVENUE,MARGINALCOST,ANDPROFITMAXIMIZATION8.3DemandandMarginalRevenueforaCompetitiveFirmBecauseeachfirminacompetitiveindustrysellsonlyasmallfractionoftheentireindustryoutput,howmuchoutputthefirmdecidestosellwillhavenoeffectonthemarketpriceoftheproduct.Becauseitisapricetaker,thedemandcurvedfacinganindividualcompetitivefirmisgivenbyahorizontalline.Chapter8:ProfitMaximizationandCompetitiveSupply9of37Copyright©2009PearsonEducation,Inc.PublishingasPrenticeHall•Microeconomics•Pindyck/Rubinfeld,7e.MARGINALREVENUE,MARGINALCOST,ANDPROFITMAXIMIZATION8.3DemandandMarginalRevenueforaCompetitiveFirmDemandCurveFacedbyaCompetitiveFirmFigure8.2Acompetitivef