范里安微观第23章讲义.ppt

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1、ChapterTwenty-ThreeIndustrySupply行业供给StructureMarketsupplyShort-runsupplyandequilibriumLong-runsupplyandequilibriumLong-runimplicationsfortaxationFixedinputsandeconomicrent(经济租金)SupplyFromACompetitiveIndustryHowarethesupplydecisionsofthemanyindividua

2、lfirmsinacompetitiveindustrytobecombinedtodiscoverthemarketsupplycurvefortheentireindustry?SupplyFromACompetitiveIndustrySinceeveryfirmintheindustryisaprice-taker,totalquantitysuppliedatagivenpriceisthesumofquantitiessuppliedatthatpricebytheindividua

3、lfirms.Short-RunSupplyInashort-runthenumberoffirmsintheindustryis,temporarily,fixed.Letnbethenumberoffirms;i=1,…,n.Si(p)isfirmi’ssupplyfunction.Short-RunSupplyInashort-runthenumberoffirmsintheindustryis,temporarily,fixed.Letnbethenumberoffirms;i=1,

4、…,n.Si(p)isfirmi’ssupplyfunction.Theindustry’sshort-runsupplyfunctionisSupplyFromACompetitiveIndustrypS1(p)pS2(p)Firm1’sSupplyFirm2’sSupplySupplyFromACompetitiveIndustrypS1(p)pS2(p)pp’p’S1(p’)S1(p’)Firm1’sSupplyFirm2’sSupplyS(p)=S1(p)+S2(p)Industry’s

5、SupplySupplyFromACompetitiveIndustrypS1(p)pS2(p)pS(p)=S1(p)+S2(p)p”p”S1(p”)S1(p”)+S2(p”)S2(p”)Firm1’sSupplyFirm2’sSupplyIndustry’sSupplySupplyFromACompetitiveIndustrypS1(p)pS2(p)pFirm1’sSupplyFirm2’sSupplyS(p)=S1(p)+S2(p)Industry’sSupplyShort-RunIndu

6、stryEquilibriumInashort-run,neitherentrynorexitcanoccur.Consequently,inashort-runequilibrium,somefirmsmayearnpositiveeconomicsprofits,othersmaysuffereconomiclosses,andstillothersmayearnzeroeconomicprofit.Short-RunIndustryEquilibriumMarketdemandShort-

7、runindustrysupplypseYseYShort-runequilibriumpriceclearsthemarketandistakenasgivenbyeachfirm.Short-RunIndustryEquilibriumy1y2y3ACsACsACsMCsMCsMCsy1*y2*y3*pseFirm1Firm2Firm3Short-RunIndustryEquilibriumy1y2y3ACsACsACsMCsMCsMCsy1*y2*y3*pseFirm1Firm2Fir

8、m3P1>0P2<0P3=0Short-RunIndustryEquilibriumy1y2y3ACsACsACsMCsMCsMCsy1*y2*y3*pseFirm1Firm2Firm3Firm1wishestoremainintheindustry.Firm2wishestoexitfromtheindustry.Firm3isindifferent.P1>0P2<0P3=0Long-RunIndustrySupplyInthelong-runeveryfirmnowintheind