微觀經(jīng)濟學(xué)（第八版-英文）課件：Markets for Factor Inputs

14.1

CompetitiveFactorMarkets14.2

EquilibriuminaCompetitiveFactorMarket14.3

FactorMarketswithMonopsonyPower14.4

FactorMarketswithMonopolyPower

MarketsforFactorInputsCHAPTEROUTLINECompetitiveFactorMarkets14.1DemandforaFactorInputWhenOnlyOneInputIsVariable●marginalrevenueproductAdditionalrevenueresultingfromthesaleofoutputcreatedbytheuseofoneadditionalunitofaninput.HowdowemeasuretheMRPL?It’stheadditionaloutputobtainedfromtheadditionalunitofthislabor,multipliedbytheadditionalrevenuefromanextraunitofoutput.●deriveddemandDemandforaninputthatdependson,andisderivedfrom,boththefirm’slevelofoutputandthecostofinputs.(14.1)Thisimportantresultholdsforanycompetitivefactormarket,whetherornottheoutputmarketiscompetitive.Inacompetitiveoutputmarket,afirmwillsellallitsoutputatthemarketpriceP.Inthiscase,themarginalrevenueproductoflaborisequaltothemarginalproductoflabortimesthepriceoftheproduct:(14.2)

MARGINALREVENUEPRODUCTFIGURE14.1Inacompetitivefactormarketinwhichtheproducerisapricetaker,thebuyer’sdemandforaninputisgivenbythemarginalrevenueproductcurve.TheMRPcurvefallsbecausethemarginalproductoflaborfallsashoursofworkincrease.Whentheproduceroftheproducthasmonopolypower,thedemandfortheinputisalsogivenbytheMRPcurve.Inthiscase,however,theMRPcurvefallsbecauseboththemarginalproductoflaborandmarginalrevenuefall.Notethatthemarginalrevenueproducttellsushowmuchthefirm

shouldbewillingtopaytohireanadditionalunitoflabor.AslongastheMRPL

isgreaterthanthewagerate,thefirmshouldhiremorelabor.Ifthemarginalrevenueproductislessthanthewagerate,thefirmshouldlayoffworkers.Theprofit-maximizingconditionistherefore

(14.3)

HIRINGBYAFIRMINTHELABORMARKET(WITHFIXEDCAPITAL)FIGURE14.2Inacompetitivelabormarket,afirmfacesaperfectlyelasticsupplyoflaborSL

andcanhireasmanyworkersasitwantsatawageratew*.Thefirm’sdemandforlaborDL

isgivenbyitsmarginalrevenueproductoflaborMRPL.Theprofit-maximizingfirmwillhireL*unitsoflaboratthepointwherethemarginalrevenueproductoflaborisequaltothewagerate.ASHIFTINTHESUPPLYOFLABORFIGURE14.3WhenthesupplyoflaborfacingthefirmsisS1,thefirmhiresL1unitsoflaboratwagew1.ButwhenthemarketwageratedecreasesandthesupplyoflaborshiftstoS2,thefirmmaximizesitsprofitbymovingalongthedemandforlaborcurveuntilthenewwageratew2isequaltothemarginalrevenueproductoflabor.Asaresult,L2unitsoflaborarehired.(14.4)Factormarketsaresimilartooutputmarketsinmanyways.Forexample,thefactormarketprofit-maximizingconditionthatthemarginalrevenueproductoflaborbeequaltothewagerateisanalogoustotheoutputmarketconditionthatmarginalrevenuebeequaltomarginalcost.RecallthatMRPL=(MPL)(MR)anddividebothsidesofequationbythemarginalproductoflabor.Then,Equation(14.4)showsthatboththehiringandoutputchoicesofthefirmfollowthesamerule:Inputsoroutputsarechosensothatmarginalrevenue(fromthesaleofoutput)isequaltomarginalcost(fromthepurchaseofinputs).Thisprincipleholdsinbothcompetitiveandnoncompetitivemarkets.

FIRM’SDEMANDCURVEFORLABOR(WITHVARIABLECAPITAL)FIGURE14.4Whentwoormoreinputsarevariable,afirm’sdemandforoneinputdependsonthemarginalrevenueproductofbothinputs.Whenthewagerateis$20,Arepresentsonepointonthefirm’sdemandforlaborcurve.Whenthewageratefallsto$15,themarginalproductofcapitalrises,encouragingthefirmtorentmoremachineryandhiremorelabor.Asaresult,theMRPcurveshiftsfromMRPL1toMRPL2,generatinganewpointConthefirm’sdemandforlaborcurve.ThusAandCareonthedemandforlaborcurve,butBisnot.DemandforaFactorInputWhenSeveralInputsAreVariableTheMarketDemandCurveAfactorinputsuchasskilledlaborisdemandedbyfirmsinmanydifferentindustries.Moreover,aswemovefromindustrytoindustry,wearelikelytofindthatfirms’demandsforlabor(whicharederivedinpartfromthedemandsforthefirms’output)varysubstantially.Therefore,toobtainthetotalmarketdemandforlaborcurve,wemustfirstdetermineeachindustry’sdemandforlabor,andthenaddtheindustrydemandcurveshorizontally.Thesecondstepisstraightforward.Addingindustrydemandcurvesforlabortoobtainamarketdemandcurveforlaborisjustlikeaddingindividualproductdemandcurvestoobtainthemarketdemandcurveforthatproduct.THEINDUSTRYDEMANDFORLABORFIGURE14.5Thedemandcurveforlaborofacompetitivefirm,MRPL1in(a),takestheproductpriceasgiven.Butasthewageratefallsfrom$15to$10perhour,theproductpricealsofalls.Thusthefirm’sdemandcurveshiftsdownwardtoMRPL2.Asaresult,theindustrydemandcurve,shownin(b),ismoreinelasticthanthedemandcurvethatwouldbeobtainediftheproductpricewereassumedtobeunchanged.DETERMININGINDUSTRYDEMANDEXAMPLE14.1THEDEMANDFORJETFUELJetfuelcostshavebeenhighlyvolatileduring

thepastseveraldecades.Understandingthe

demandforjetfuelisimportanttomanagersof

bothoilrefineriesandairlines.Thepriceelasticityofdemandforjetfuel

dependsbothontheabilitytoconservefuel

andontheelasticitiesofdemandandsupplyoftravel.Overall,theresultsshowthatthedemandforjetfuelasaninputtotheproductionofairlineflight-milesisveryinelastic.Intheshortrun,thereisnogoodsubstituteforjetfuel.Thelong-runelasticityofdemandishigher,however,becauseairlinescaneventuallyintroducemoreenergy-efficientairplanes.TABLE14.1

SHORT-RUNPRICEELASTICITYOFDEMANDFORJETFUELAIRLINEELASTICITYAIRLINEELASTICITYAmerican–.06Delta–.15Continental–.09United–.10EXAMPLE14.1THEDEMANDFORJETFUELTHESHORT-ANDLONG-RUNDEMANDFORJETFUELFIGURE11.6Theshort-rundemandforjetfuelMRPSRismoreinelasticthanthelong-rundemandMRPLR.Intheshortrun,airlinescannotreducefuelconsumptionmuchwhenfuelpricesincrease.Inthelongrun,however,theycanswitchtolonger,morefuel-efficientroutesandputmorefuel-efficientplanesintoservice.TheSupplyofInputstoaFirm●marginalexpenditurecurve Curvedescribingtheadditionalcostofpurchasingoneadditionalunitofagood.●

averageexpenditurecurve Supplycurverepresentingthepriceperunitthatafirmpaysforagood.Profitmaximizationrequiresthatmarginalrevenueproductbeequaltomarginalexpenditure:Inthecompetitivecase,theconditionforprofitmaximizationisthatthepriceoftheinputbeequaltomarginalexpenditure:(14.6)(14.5)

AFIRM’SINPUTSUPPLYINACOMPETITIVEFACTORMARKETFIGURE14.7Inacompetitivefactormarket,afirmcanbuyanyamountoftheinputitwantswithoutaffectingtheprice.Therefore,thefirmfacesaperfectlyelasticsupplycurveforthatinput.Asaresult,thequantityoftheinputpurchasedbytheproduceroftheproductisdeterminedbytheintersectionoftheinputdemandandsupplycurves.In(a),theindustryquantitydemandedandquantitysuppliedoffabricareequatedatapriceof$10peryard.In(b),thefirmfacesahorizontalmarginalexpenditurecurveatapriceof$10peryardoffabricandchoosestobuy50yards.TheMarketSupplyofInputsBACKWARD-BENDINGSUPPLYOFLABORFIGURE14.8Whenthewagerateincreases,thehoursofworksuppliedincreaseinitiallybutcaneventuallydecreaseasindividualschoosetoenjoymoreleisureandtoworkless.

Thebackward-bendingportionofthelaborsupplycurveariseswhentheincomeeffectofthehigherwage(whichencouragesmoreleisure)isgreaterthanthesubstitutioneffect(whichencouragesmorework).SUBSTITUTIONANDINCOMEEFFECTSOFAWAGEINCREASEFIGURE14.9Whenthewagerateincreasesfrom$10to$30perhour,theworker’sbudgetlineshiftsfromPQtoRQ.Inresponse,theworkermovesfromAtoBwhiledecreasingworkhoursfrom8to5.Thereductioninhoursworkedarisesbecausetheincomeeffectoutweighsthesubstitutioneffect.Inthiscase,thesupplyoflaborcurveisbackwardbending.720EXAMPLE14.2LABORSUPPLYFORONE-ANDTWO-EARNERHOUSEHOLDSTABLE14.2

ELASTICITIESOFLABORSUPPLY(HOURSWORKED)GROUPHEAD’SHOURS

WITHRESPECTTO

HEAD’SWAGESPOUSE’SHOURSWITHRESPECTTO

SPOUSE’SWAGEHEAD’SHOURS

WITHRESPECTTO

SPOUSE’SWAGEUnmarriedmales,nochildren.026Unmarriedfemales,children.106Unmarriedfemales,nochildren.011One-earnerfamily,children–.078One-earnerfamily,nochildren.007Two-earnerfamilychildren–.002–.086–.004Two-earnerfamily,nochildren–.107–.028–.059Oneofthemostdramaticchangesinthelabormarketinthetwentiethcenturyhasbeentheincreaseinwomen’sparticipationinthelaborforce.Onewaytodescribetheworkdecisionsofthevariousfamilygroupsistocalculatelaborsupplyelasticities.Whenahigherwagerateleadstofewerhoursworked,thelaborsupplycurveisbackwardbending:Theincomeeffect,whichencouragesmoreleisure,outweighsthesubstitutioneffect,whichencouragesmorework.Theelasticityoflaborsupplyisthennegative.EquilibriuminaCompetitiveFactorMarket14.2LABORMARKETEQUILIBRIUMFIGURE14.10Inacompetitivelabormarketinwhichtheoutputmarketiscompetitive,theequilibriumwagewcisgivenbytheintersectionofthedemandforlaborandthesupplyoflaborcurve(pointA).Whentheproducerhasmonopolypower,themarginalvalueofaworkervMisgreaterthanthewagewM.Thustoofewworkersareemployed.(PointBdeterminesthequantityoflaborthatthefirmhiresandthewageratepaid.)EconomicRentForafactormarket,economicrentisthedifferencebetweenthepaymentsmadetoafactorofproductionandtheminimumamountthatmustbespenttoobtaintheuseofthatfactor.ECONOMICRENTFIGURE14.11Theeconomicrentassociatedwiththeemploymentoflaboristheexcessofwagespaidabovetheminimumamountneededtohireworkers.

TheequilibriumwageisgivenbyA,attheintersectionofthelaborsupplyandlabordemandcurves.Becausethesupplycurveisupwardsloping,someworkerswouldhaveacceptedjobsforawagelessthanw*.

Thegreen-shadedareaABw*istheeconomicrentreceivedbyallworkers.LANDRENTFIGURE14.12Whenthesupplyoflandisperfectlyinelastic,themarketpriceoflandisdeterminedatthepointofintersectionwiththedemandcurve.Theentirevalueofthelandisthenaneconomicrent.WhendemandisgivenbyD1,theeconomicrentperacreisgivenbys1,andwhendemandincreasestoD2,rentperacreincreasestos2.EXAMPLE14.3PAYINTHEMILITARYTodealwithashortageofskilledlabor,the

militarychangeditswagestructureto

maintainaneffectivefightingforce.Toreduce

theshortage,themilitaryofferedpayraises,

reenlistmentbonusestargetedatskilledjobs,

andemphasisonthebenefitsofsubsidizedhousing,food,medicalcare,education,andtechnicaltraining.THESHORTAGEOFSKILLEDMILITARYPERSONNELFIGURE11.13Whenthewagew*ispaidtomilitarypersonnel,thelabormarketisinequilibrium.Whenthewageiskeptbeloww*,atw0,thereisashortageofpersonnelbecausethequantityoflabordemandedisgreaterthanthequantitysupplied.FactorMarketswithMonopsonyPower14.3Insomefactormarkets,individualbuyershavebuyerpowerthatallowsthemtoaffectthepricestheypay.Oftenthishappenseitherwhenonefirmisamonopsonybuyerorthereareonlyafewbuyers,inwhichcaseeachfirmhassomemonopsonypower.Firmswithmonopsonypowerbuylargequantitiesandcannegotiatelowerpricesthanthosechargedsmallerpurchasers.Inothercases,theremightbeonlytwoorthreesellersofafactorandadozenormorebuyers,buteachbuyernonethelesshasbargainingpower—itcannegotiatelowpricesbecauseitmakeslargeandinfrequentpurchasesandcanplaythesellersoffagainsteachotherwhenbargainingoverprice.Throughoutthissection,wewillassumethattheoutputmarketisperfectlycompetitive.Inaddition,becauseasinglebuyeriseasiertovisualizethanseveralbuyerswhoallhavesomemonopsonypower,wewillrestrictourattentionatfirsttopuremonopsony.MonopsonyPower:MarginalandAverageExpenditureMARGINALANDAVERAGEEXPENDITUREFIGURE14.14Whenthebuyerofaninputhasmonopsonypower,themarginalexpenditurecurveliesabovetheaverageexpenditurecurvebecausethedecisiontobuyanextraunitraisesthepricethatmustbepaidforallunits,notjustforthelastone.ThenumberofunitsofinputpurchasedisgivenbyL*,attheintersectionofthemarginalrevenueproductandmarginalexpenditurecurves.Thecorrespondingwageratew*islowerthanthecompetitivewagewc.LCPurchasingDecisionswithMonopsonyPowerBargainingPowerAbuyerwithmonopsonypowermaximizesnetbenefit(utilitylessexpenditure)fromapurchasebybuyinguptothepointwheremarginalvalue(MV)isequaltomarginalexpenditure:Forafirmbuyingafactorinput,MVisjustthemarginalrevenueproductofthefactorMRP.(14.7)Theamountofbargainingpowerthatabuyerorsellerhasisdeterminedinpartbythenumberofcompetingbuyersandcompetingsellers.Butitisalsodeterminedbythenatureofthepurchaseitself.EXAMPLE14.4MONOPSONYPOWERINTHEMARKETFORBASEBALLPLAYERSIntheUnitedStates,majorleaguebaseballisexempt

fromtheantitrustlaws.Thisexemptionallowed

baseballteamowners(before1975)tooperatea

monopsonisticcartel.Likeallcartels,thisonedependedonanagreement

amongowners.Theagreementinvolvedanannual

draftofplayersandareserveclausethateffectivelytiedeachplayertooneteamforlife,therebyeliminatinginterteamcompetitionforplayers.Asaresult,baseballownershadmonopsonypowerinnegotiatingnewcontractswiththeirplayers.Duringthe1960sandearly1970s,baseballplayers’salarieswerefarbelowthemarketvalueoftheirmarginalproducts.Fortunatelyfortheplayers,andunfortunatelyfortheowners,therewasastrikein1972followedbyalawsuitbyoneplayerandanarbitratedlabor-managementagreement.Thisprocesseventuallyledin1975toanagreementbywhichplayerscouldbecomefreeagentsafterplayingforateamforsixyears.Theresultwasaninterestingexperimentinlabormarketeconomics.Between1975and1980,themarketforbaseballplayersadjustedtoanewpost-reserveclauseequilibrium.Theaverageplayer’ssalarydoubledinrealterms.EXAMPLE14.5TEENAGELABORMARKETSANDTHEMINIMUMWAGEIncreasesinthenationalminimumwagerate(which

was$4.50inearly1996and$7.20in2011)were

controversial,raisingthequestionofwhetherthecost

ofanyunemploymentthatmightbegeneratedwould

beoutweighedbythebenefitofhigherincomesto

thosewhosewageshavebeenincreased.Astudyoftheeffectsoftheminimumwageonemploymentinfast-foodrestaurantsinNewJerseyfoundthatemploymenthadactuallyincreasedby13percentaftertheminimumwagewentup.Onepossibilityisthatrestaurantsrespondedtothehigherminimumwagebyreducingfringebenefitsandprovidinglesson-the-job-training.AnalternativeexplanationfortheincreasedNewJerseyemploymentholdsthatthelabormarketforteenage(andother)unskilledworkersisnothighlycompetitive.Thereisnoevidenceofmonopsonypowerinthefast-foodindustry.Iffirmsdohavemonopsonypowerbutthefast-foodmarketiscompetitive,thentheincreaseintheminimumwageshouldhavenoeffectonthepriceoffastfood.Theanalysisoftheminimumwageremainshotlydebated.Newempiricalstudiesshouldshedmorelightontheeffectsoftheminimumwage.FactorMarketswithMonopolyPower14.4MonopolyPowerovertheWageRateMONOPOLYPOWEROFSELLERSOFLABORFIGURE14.15Whenalaborunionisamonopolist,itchoosesamongpointsonthebuyer’sdemandforlaborcurveDL.Thesellercanmaximizethenumberofworkershired,atL*,byagreeingthatworkerswillworkatwagew*.ThequantityoflaborL1thatmaximizestherentearnedbyemployeesisdeterminedbytheintersectionofthemarginalrevenueandsupplyoflaborcurves;unionmemberswillreceiveawagerateofw1.Finally,iftheunionwishestomaximizetotalwagespaidtoworkers,itshouldallowL2unionmemberstobeemployedatawagerateofw2.Atthatpoint,themarginalrevenuetotheunionwillbezero.UnionizedandNonunionizedWorkersWAGEDISCRIMINATIONINUNIONIZEDANDNONUNIONIZEDSECTORSFIGURE14.16Whenamonopolisticunionraisesthewageintheunionizedsectoroftheeconomyfromw*towU,employmentinthatsectorfalls,asshownbythemovementalongthedemandcurveDU.Forthetotalsupplyoflabor,givenbySL,toremainunchanged,thewageinthenonunionizedsectormustfallfromw*towNU,asshownbythemovementalongthedemandcurveDNU.EXAMPLE14.6THEDECLINEOFPRIVATE-SECTORUNIONISMForseveraldecades,themembershipoflaborunionshasbeendeclining.Aswemovedintothe21stcenturytherateofdeclinebegantodiminishandithasstabilizedinrecentyearsatabout12percent.In2010,unionizationinthepublicsector,was36.2percent,andonly6.9%intheprivatesector.Duringthepasttwodecades,anumberofeconomicforceshaveledtoafurthernarrowingoftheunion-nonunionwagedifferential.Thedemandforunionizedemployeeshasbecomeincreasinglyelasticovertimeasfirmshavefounditeasiertosubstitutecapitalforskilledlaborintheproductionprocess.Globalizationhasmeantthatmanycompanieswereabletoorganizetheirproductionprocessessoastohirenon-unionlabor,eitherwithinoroutsidetheUnitedStates.Facedwithanelasticde