中财-微观经济学-第八章-利润最大化和竞争性供给

1第八章利润最大化和竞争性供给本章概要完全竞争市场的利润最大化以及短期、长期均衡2假设：厂商追求利润最大化不符合三条件定义：完全竞争市场分析框架：结论短期供给线；三种长期供给线经验研究()()()()MRqMCqMRqMCqPMRAR符合三条件竞争市场利润最大化与均衡短期均衡：短期供给线、生产者剩余长期均衡：长期供给线长期利润最大化受冲击：税收效应31.1厂商追求利润最大化的假设()()()max()qRqTCqq42.1完全竞争市场的定义符合下面三个特征的市场称为完全竞争市场：（1）产品同质（Producthomogeneity）；（2）厂商和消费者都是价格接受者（Pricetaking）；（3）厂商无成本进入与退出（Freeentryandexit）5IndustryD$4SPrice$perbushelOutput(millionsofbushels)100（1）产品同质：存在市场均衡价格P6d$4Output(bushels)Price$perbushel100200FirmIndustryD$4SPrice$perbushelOutput(millionsofbushels)100DPP（2）价格接受者：厂商面临的需求线为7d$4Output(bushels)Price$perbushel100200FirmijPAVCiPAVCj（3）厂商无成本进退：，退出；，进入AVCiAVCj8P=MR=AROutput(bushels)Price$perbushel100200Firm2.2完全竞争市场的重要性质PMRAR9证明()()()RqPqdRqMRPdqRqARPqPqMRARP对某厂商在完全竞争上某企业的与没有关系：103.1.分析框架：数学解221.1:()()()max()()()()()(max()0()())()0MRqMCqMRqRqTCqqdqdRqdTCqdqqMCdqdqqdqdqq由的一阶条件：的二阶条件：1.2:PMRAR由1.2()()()(:)MRqMCqMRqMCqPMRAR由1.1;11q210203040Price50MCAVCAC01234567891011Outputq*AR=MR=PAq1:MRMCq2:MCMRq*:MC=MRq1LostProfitforq2q*LostProfitforq2q*3.2.分析框架：几何解12•当MRMC时•增加产量所增加的收益大于所增加的成本，因而总利润可以增加；•当MRMC时•减少产量所减少的收益小于所减少的成本，因而总利润可以增加；•当MR=MC时•无论怎样调整产量，总利润都只会减少而不会增加。1310203040Price5001234567891011OutputMCAVCACq*AR=MR=PA4.1.短期均衡MR=MC情形1：利润为正()0qARqACq1410203040Price5001234567891011OutputMCAVCACq*AR=MR=PA情形2：利润为0()0qARqACq1510203040Price5001234567891011OutputMCAVCACq*AR=MR=PA情形3：弥补全部可变成本之外还能弥补部分固定成本()0qARqACq1610203040Price5001234567891011OutputMCAVCACq*AR=MR=PA情形4：刚好弥补全部可变成本，不能弥补一点固定成本()0qARqACq1710203040Price5001234567891011OutputMCAVCACq*AR=MR=PA情形5：甚至不能弥补全部可变成本，更谈不上弥补一点固定成本()0qARqACq18关于短期均衡的总结•短期均衡的条件是：SMC=SMR=P•短期均衡中利润可能为正，为零，为负。19Price($perunit)OutputMCAVCACP=AVCP2q2P1q1S4.2.1由短期均衡的五种情形可推导出完全竞争厂商的短期供给线：几何204.2.2由短期均衡的五种情形可推导出完全竞争厂商的短期供给线：数学11(1)min:()()(2)min:0(),min0,minPSAVCPSMCqqSMCPPSAVCqqSMCPPSAVCqPSAVC21ProducerSurplusPrice($perunitofoutput)OutputAVCMCABPq*4.3.1由短期条件理解生产者剩余的定义：几何CD224.3.2由短期条件理解生产者剩余的定义：数学000(())()()[()(0)]()()00qqqPSPMCqdqPqMCqdqdTCqPqdqdqPqTCqTCPqVCqPqAVCqqABqDCqABCD23生产者剩余与经济利润的区别PSRVCRVCFC24DP*q*ProducerSurplusPrice($perunitofoutput)OutputS市场的生产者剩余25q1BCADPriceOutputP=MR=AR$40SACSMCq3LACLMC4.4.1从长期利润最大化到长期均衡()LMRPLMC长期利润最大化条件：26PriceOutputP=MR=AR$40q3LACLMC4.4.2从长期利润最大化到长期均衡()();;minLMRPLMCSMRPSMCSMCSACPLAC长期均衡(零经济利润)条件：；P=MR=AR$40274.5行业的长期供给曲线11111111;;;;tttttKLttttttttKKLLttttKKLLttttKKLLPKPLCKKLLPPPPPPPPPPPP比如：时：成本不变行业：成本递增行业：成本递减行业：28LACSMCq1D1S1Q1P1D2P2P2q2S2Q2OutputOutput$$P1SL（1）成本不变行业29OutputOutput$$D1S1q1P1Q1P1SLSMC1LAC1SMC2LAC2P3S2P3Q3q2P2D2Q2P2（2）成本递增行业30S2SLP3Q3P3SMC2LAC2OutputOutput$$P1D1S1P1Q1q1SMC1LAC1q2P2D2Q2P2（3）成本递减行业31Price($perunitofoutput)OutputAVC1MC1P1q1tMC2=MC1+taxAVC24.5长期利润最大化受到税收冲击的情形q2321212121290min:min:0PPAVCqqPAVCq教材的意思：33TheSverigesRiksbankPrizeinEconomicSciencesinMemoryofAlfredNobel2009ElinorOstrom1/2USAIndianaUniversityBloomington,IN,USAb.1933forheranalysisofeconomicgovernance,especiallythecommons34TheSverigesRiksbankPrizeinEconomicSciencesinMemoryofAlfredNobel2009OliverE.Williamson1/2USAUniversityofCaliforniaBerkeley,CA,USAb.1932forhisanalysisofeconomicgovernance,especiallytheboundariesofthefirm3536Economicgovernance:theorganizationofcooperationElinorOstromhasdemonstratedhowcommonpropertycanbesuccessfullymanagedbyuserassociations.PressRelease12October200937OliverWilliamsonhasdevelopedatheorywherebusinessfirmsserveasstructuresforconflictresolution.38Overthelastthreedecadestheseseminalcontributionshaveadvancedeconomicgovernanceresearchfromthefringetotheforefrontofscientificattention.39Economictransactionstakeplacenotonlyinmarkets,butalsowithinfirms,associations,households,andagencies.Whereaseconomictheoryhascomprehensivelyilluminatedthevirtuesandlimitationsofmarkets,ithastraditionallypaidlessattentiontootherinstitutionalarrangements.40•TheresearchofElinorOstromandOliverWilliamsondemonstratesthateconomicanalysiscanshedlightonmostformsofsocialorganization.41ElinorOstromhaschallengedtheconventionalwisdomthatcommonpropertyispoorlymanagedandshouldbeeitherregulatedbycentralauthoritiesorprivatized.Basedonnumerousstudiesofuser-managedfishstocks,pastures,woods,lakes,andgroundwaterbasins,Ostromconcludesthattheoutcomesare,moreoftenthannot,betterthanpredictedbystandardtheories.42Sheobservesthatresourceusersfrequentlydevelopsophisticatedmechanismsfordecision-makingandruleenforcementtohandleconflictsofinterest,andshecharacterizestherulesthatpromotesuccessfuloutcomes.43OliverWilliamsonhasarguedthatmarketsandhierarchicalorganizations,suchasfirms,representalternativegovernancestructureswhichdifferintheirapproachestoresolvingconflictsofinterest.44Thedrawbackofmarketsisthattheyoftenentailhagglinganddisagreement.Thedrawbackoffirmsisthatauthority,whichmitigatescontention,canbeabused.Competitivemarketsworkrelativelywellbecausebuyersandsellerscanturntoothertradingpartnersincaseofdissent.45Butwhenmarketcompetitionislimited,firmsarebettersuitedforconflictresolut