管經(jīng)-管理經(jīng)濟學課件

第12章：具有市場力企業(yè)的決策LearningObjectivesDefinemarketpoweranddescribemeasurementofmarketpowerExplainwhyentrybarriersarenecessaryforlongrunmarketpoweranddiscussmajortypesofentrybarriersFindtheprofit‐maximizingoutput,price,andinputusageforamonopolistandmonopolisticcompetitorEmployempiricallyestimatedorforecasteddemand,averagevariablecost,andmarginalcosttocalculateprofit‐maximizingoutputandpriceformonopolisticormonopolisticallycompetitivefirmsSelectproductionlevelsatmultipleplantstominimizethetotalcostofproducingagiventotaloutputforafirm壟斷Monopoly市場只有一個企業(yè)生產(chǎn)和銷售沒有相近替代品的差異化產(chǎn)品或服務(wù)新企業(yè)被阻止進入市場TheBiggestContract

intheentirehistoryofGazpromThe30-yearcontractstipulatesthat38billioncubicmetersofRussiangaswillbeannuallysuppliedtoChinaTheAntitrustCaseAgainstMicrosoftSoftwarepioneer,monopolist,orboth?IsGoogleaMonopoly?

In2011,Microsoftfiledacomplaintwith

theEuropeanCommissionthatGoogle

wasusingitsdominantpositionasan

Internetsearchenginetocreatean

effectivemonopolybyexcludingcompetitors.Googlearguesthatitsdominantmarketshareisduetothehigherqualityofitssearchengine,notanyattemptsthecompanyhasmadetoreducetheaccessofothersearchenginestoonlinecontent.市場力MarketPower企業(yè)提高價格而不失去全部銷售量的能力任何面臨向下傾斜需求曲線的企業(yè)都具有一定的市場力使得企業(yè)能夠定價高于平均成本并且獲取經(jīng)濟利潤

（如果需求和成本情況允許）市場界定市場界定：在一定的地理區(qū)域內(nèi)，識別所有的競爭廠商和競爭產(chǎn)品及服務(wù)。一個市場由所有生產(chǎn)相似產(chǎn)品的廠商構(gòu)成。一個正確定義的市場，必須能夠包括所有消費者認同可以相互替代的產(chǎn)品和服務(wù)?？梢酝ㄟ^價格上升的影響來界定相近替代品：如果對市場的定義十分狹隘，那么價格的上升會使廠商的銷量和利潤大幅下降，說明市場界定過?。粩U大市場范圍，直到利潤上升為止。如可口可樂的市場（DrPepperin1986）市場力的度量市場力的程度與需求價格彈性反向相關(guān)企業(yè)需求越缺乏彈性，企業(yè)的市場力就越大企業(yè)產(chǎn)品越缺乏相應的替代品，需求價格彈性（絕對值）越小，企業(yè)的市場力越大當完全彈性需求（水平需求）時，企業(yè)沒有市場力市場力的度量勒納指數(shù)（Lernerindex）估計價格水平與完全競爭條件下價格的偏離范圍

：市場力的度量勒納指數(shù)完全競爭條件下等于零隨著市場力水平的提高而增加也等于

–1/E，表明指數(shù)（市場力）與需求價格彈性反向相關(guān)需求價格彈性（絕對值）越小，指數(shù)越大，市場力水平也越高市場力的度量如果消費者認為兩種產(chǎn)品是可以替代的，那么需求的交叉價格彈性

(EXY)

為正產(chǎn)品的交叉價格彈性越高，兩種產(chǎn)品的替代性越強，生產(chǎn)這兩種產(chǎn)品的公司擁有的市場力就越弱集中度的衡量（赫芬達爾-赫希曼指數(shù)）TheDepartmentofJusticeandtheFederalTradeCommissionMergerGuidelinesMEASUREOFCONCENTRATION(Herfindahl-HirschmanIndex,HHI)1firm,100%marketshare(amonopoly):HHI=1002=10,0002firms,eachwitha50%marketshare:HHI=502+502=5,0004firms,withmarketsharesof30%,30%,20%,and20%:

HHI=302+302+202+202=2,60010firms,eachwithmarketsharesof10%:HHI=10(102)=1,000合并標準MERGERSTANDARDS合并后的HHI指數(shù)低于1,000.該市場不是集中的,因此合并不會遭到挑戰(zhàn)；合并后的HHI指數(shù)介于1,000和1,800之間.這些市場的集中度不高，如果合并使HHI指數(shù)的提高低于100，這一合并不會受到挑戰(zhàn)；如果合并使HHI指數(shù)提高大于100，則可能受到挑戰(zhàn).合并后HHI指數(shù)高于1,800.這些市場是高度集中的。使HHI指數(shù)提高低于50的合并，不會受到挑戰(zhàn)；提高幅度在50到100之間的合并可能受到挑戰(zhàn)；提高幅度超過100的合并必然受到挑戰(zhàn).1992年兼并指南下的兼并安全港安全不安全不安全安全安全不安全安全安全安全兼并后的HHIHHI增長1800100010050市場力的決定因素新廠商進入市場，會增加替代品的數(shù)量，從而削弱目前企業(yè)的市場力只有當存在比較強的進入壁壘時，市場中的廠商才能擁有較高水平的市場力強進入壁壘阻礙了新廠商的進入，從而保證了市場現(xiàn)存廠商的利潤常見的進入壁壘政府設(shè)置的壁壘特許權(quán)或執(zhí)照（電力、自來水、出租車等）專利和版權(quán)等自然壟斷NaturalMonopoly（或者，規(guī)模經(jīng)濟Economiesofscale）在與產(chǎn)品需求相關(guān)的產(chǎn)量范圍內(nèi)，如果廠商的長期平均成本曲線是呈下降趨勢的，那么會產(chǎn)生很強的進入壁壘沉沒成本的進入壁壘W(wǎng)ithanaturalmonopoly,theaveragetotalcostcurve

isstillfallingwhenitcrosses

thedemandcurve(pointA).Ifonlyonefirmisproducing

electricpowerinthemarket,anditproduceswherethe

averagecostcurve

intersectsthedemandcurve,averagetotalcostwillequal

$0.04perkilowatt-hourof

electricityproduced.Ifthemarketisdivided

betweentwofirms,eachproducing15billion

kilowatt-hours,theaveragecostofproducingelectricityrisesto$0.06perkilowatt-hour(pointB).Inthiscase,ifonefirmexpandsproduction,itcanmovedowntheaveragetotalcostcurve,loweritsprice,anddrivetheotherfirmoutofbusiness.NaturalmonopolyAsituationinwhicheconomiesofscalearesolargethatonefirmcansupplytheentiremarketataloweraveragetotalcostthancantwoormorefirms.常見的進入壁壘品牌效應Brandloyalties消費者對現(xiàn)有企業(yè)的忠誠度，使那些新進入市場的企業(yè)很難發(fā)現(xiàn)足夠的買者，因而無法進入Realemon濃縮檸檬汁要素壁壘Inputbarriers一個企業(yè)控制了某一生產(chǎn)過程的關(guān)鍵投入要素美國鋁業(yè)（Alcoa），或者資本、渠道等iOSAdiamondisforeverDeBeerspromotedthesentimentalvalueofdiamondsasawaytomaintainitspositioninthediamondmarket.TheEndoftheChristmasPlantMonopolyFormanyyears,thePaulEckeRanchinEncinitas,

Californiahadamonopolyonpoinsettias,whose

strikingredandgreencolorsthatblossominthe

wintermakethemidealforChristmasdecorating.Afterdiscoveringanewtechniqueforgrowingthe

wildflowerthatwaskeptsecretfordecades,the

Eckefamilywasabletomaintainamonopolyonits

commercialproductionwithoutacquiringapatent,untilauniversityresearcherdiscoveredthe

techniqueandpublisheditinanacademicjournal.Asaresult,manynewfirmsquicklyenteredthe

industryandthepriceofpoinsettiasplummeted.常見的進入壁壘網(wǎng)絡(luò)外延Networkexternalities近20年計算機技術(shù)、互聯(lián)網(wǎng)、新軟件發(fā)展迅猛信息產(chǎn)品特點：無成本復制、快速擴散、不變質(zhì)某種產(chǎn)品或服務(wù)的效用會隨著使用人數(shù)的增加而增加，該產(chǎn)品或服務(wù)在消費中存在網(wǎng)絡(luò)效應例子：微信，京東，大眾點評網(wǎng)，標準，信用卡，DVD與碟片，蘋果硬件、系統(tǒng)與軟件，維護等一旦企業(yè)建立了巨大的消費者網(wǎng)絡(luò)，新企業(yè)就難以進入市場，首先建立用戶基礎(chǔ)的企業(yè)具有先入優(yōu)勢POSITIVENETWORKEXTERNALITYinwhichaconsumerwishestopossessagoodinpartbecauseothersdoBandwagonEffect攀比效應Withapositivenetworkexternality,thequantityofagoodthatanindividualdemandsgrowsinresponsetothegrowthofpurchasesbyotherindividuals.Here,asthepriceoftheproductfallsfrom$30to$20,thebandwagoneffectcausesthedemandforthegoodtoshifttotheright,fromD40toD80.NEGATIVENETWORKEXTERNALITYinwhichaconsumerwishestoownanexclusiveoruniquegood.SnobEffect虛榮效應Thesnobeffectisanegativenetworkexternalityinwhichthequantityofagoodthatanindividualdemandsfallsinresponsetothegrowthofpurchasesbyotherindividuals.Here,asthepricefallsfrom$30,000to$15,000andmorepeoplebuythegood,thesnobeffectcausesthedemandforthegoodtoshifttotheleft,fromD2toD6.Althoughnotfirsttomarket,Bicultimatelywasmoresuccessfulthanthefirmthatpioneeredballpointpens.(vs.Reynolds)IsBeingtheFirstFirmintheMarketaKeytoSuccess?Thefirmsthatwerefirsttointroduceaproductultimatelylostouttoerswhodidabetterjobofprovidingconsumerswithproductsthatweremorereliable,lessexpensive,moreconvenient,orotherwiseprovidedgreatervalue.iPodHPLaserJetP&GPampersIE常見的進入壁壘消費者鎖定Consumerlock-in如果潛在的進入者認為昂貴的轉(zhuǎn)換成本使現(xiàn)有消費者不會轉(zhuǎn)向其它品牌時，他們就被阻止進入了轉(zhuǎn)換成本：安裝或入會費；尋找可能替代品及其價格的成本；學習如何使用新的或者不同產(chǎn)品或服務(wù)的成本。高轉(zhuǎn)換成本可能是自然形成的，也可能是企業(yè)戰(zhàn)略性創(chuàng)造的例子：從Office到WPS?從Nikon到Canon？壟斷廠商面臨的需求和邊際收益市場需求曲線就是壟斷企業(yè)的需求曲線壟斷者想要售出更多的產(chǎn)品，就必須降低價格（統(tǒng)一定價時）除了第一件產(chǎn)品，其余每件產(chǎn)品出售帶來的邊際收益都低于其價格當MR

為正值(負值)，需求具有彈性(缺乏彈性)壟斷廠商面臨的需求和邊際收益壟斷下的短期利潤最大化(圖12.3)壟斷下的短期利潤最大化如果部分需求曲線對應的價格水平高于平均變動成本，壟斷廠商在短期內(nèi)會進行生產(chǎn)通過MR=MC時的產(chǎn)出量，可以達到利潤最大化，或虧損最小化壟斷下的短期損失最小化(圖12.4)壟斷下的短期利潤最大化若P>ATC,企業(yè)獲利若ATC>P>AVC,企業(yè)產(chǎn)生虧損，但短期內(nèi)仍繼續(xù)生產(chǎn)若在任何產(chǎn)出水平需求曲線都低于AVC,企業(yè)會停止生產(chǎn)，以使虧損的部分只是固定成本不同于完全競爭市場，這里AVC不是最小值A(chǔ)VC處于下降階段MaximizingProfit

P(Q)=24-Q

C(Q)=Q2+12

MonopolyExampleInversedemandfunction:Canbeusedtofindthemarginalrevenuefunction:

QuadraticSRcostfunction:Canbeusedtofindthemarginalcostfunction:

Profit-maximizingoutputisobtainedbyproducingQ*:SolvingthisexpressionrevealsQ*=6Theinversedemandfunctionindicatesthatpeoplearewillingtopayp=$18for6unitsofoutput.AppleintroduceditsiPodin2001DataMarginalcost=$200Fixedcost=$736millionDemandfunction:P=600-25Q(inmillion)Questions:Whatwereitsprofitmaximizingpriceandquantity,profit,andLernerIndex,priceelasticity?AnswerAC=200+736/QMR=600-50QQ=8million;P=$400Profit=(P-AC)Q=[400-(200+736/8)]*8=$864millionLernerIndex=[P-MC]/P=[400-200]/400=1/2PriceElasticity=-1/LI=-2Graph壟斷下的長期利潤最大化(圖12.5)壟斷下的長期利潤最大化壟斷廠商通過選擇一個能夠使MR=LMC的產(chǎn)出水平只要

PLAC，企業(yè)就實現(xiàn)了利潤最大化如果

P<LAC，企業(yè)就退出市場壟斷廠商將調(diào)整企業(yè)規(guī)模達到最優(yōu)水平在利潤最大化對應的產(chǎn)出水平上，短期平均成本曲線正好與長期成本曲線相切SHIFTSINDEMANDShiftingthedemandcurveshowsthatamonopolisticmarkethasnosupplycurve—i.e.,thereisnoone-to-onerelationshipbetweenpriceandquantityproduced.In(a),thedemandcurveD1shiftstonewdemandcurveD2.ButthenewmarginalrevenuecurveMR2intersectsmarginalcostatthesamepointastheoldmarginalrevenuecurveMR1.Theprofit-maximizingoutputthereforeremainsthesame,althoughpricefallsfromP1toP2.In(b),thenewmarginalrevenuecurveMR2intersectsmarginalcostatahigheroutputlevelQ2.Butbecausedemandisnowmoreelastic,priceremainsthesame.利潤最大化決策的一般原則企業(yè)應該生產(chǎn)還是關(guān)門？對應某一產(chǎn)量水平，只要市場價格超過平均可變成本，就要生產(chǎn)：P>=AVC，否則關(guān)門如果生產(chǎn)，應該生產(chǎn)多少，價格為多少？為了保證利潤最大化，在邊際收益等于邊際成本（MR=MC）點上決定產(chǎn)量，并以此產(chǎn)量按需求曲線決定價格ReplyfromProf.Christopher利潤最大化產(chǎn)量與價格決策的實施Step1:估計需求函數(shù)廣義需求函數(shù)估計（運用第七章的統(tǒng)計技術(shù)）用預測的外生變量的未來值代入估計的需求函數(shù)，得到利潤最大化產(chǎn)量與價格決策的實施Step2:求需求函數(shù)的反函數(shù)解出P利潤最大化產(chǎn)量與價格決策的實施Step3:求邊際收益當需求函數(shù)表示為

P=A+BQ，邊際收益函數(shù)寫為利潤最大化產(chǎn)量與價格決策的實施Step4:估計AVC&SMC運用第十章的統(tǒng)計技術(shù)AVC=a+bQ+cQ2SMC=a+2bQ+3cQ2Step5:找出

MR=SMC的產(chǎn)出水平令邊際收益等于邊際成本，解出

Q*兩個解中大的一個就是利潤最大化的產(chǎn)出量Step6:找出最優(yōu)價格把

Q*

代入反需求函數(shù)，得P*=A+BQ*只有PAVC時，所得出的

Q*&P*

才是最優(yōu)的利潤最大化產(chǎn)量與價格決策的實施利潤最大化產(chǎn)量與價格決策的實施Step7:檢驗關(guān)門法則把

Q*

代入到估計的AVC方程若

P*

AVC*，產(chǎn)出為Q*

且售價為

P*

若P*

<AVC*，短期關(guān)門AVC*=a+bQ*+cQ*2利潤最大化產(chǎn)量與價格決策的實施Step8:計算利潤或虧損Profit=TR–TC

=PxQ*-AVCxQ*-TFC=(P–AVC)Q*-TFC若P<AVC，壟斷企業(yè)關(guān)門并且利潤為-TFCAztecElectronics的利潤最大化因為擁有專利，Aztec擁有市場力銷售高級無線立體聲耳機，市場需求：固定成本$270,000，平均變動成本：

AVC=28–0.005Q+0.000001Q2預計2015年：M=$45,000,PR=$800企業(yè)的利潤最大化決策是什么？AztecElectronics的利潤最大化估計需求和邊際收益函數(shù)AztecElectronics的利潤最大化求反需求函數(shù)AztecElectronics的利潤最大化確定邊際收益函數(shù)P=100–0.002QMR=100–0.004QAztecElectronics的需求和邊際收益AztecElectronics的利潤最大化估計平均變動成本函數(shù)和邊際成本函數(shù)estimatedAVCequation:AVC=28–0.005Q+0.000001Q2Then,SMC=28–(2x0.005)Q+(3x0.000001)Q2=28–0.01Q+0.000003Q2AztecElectronics的利潤最大化確定產(chǎn)量令

MR=MC

并求解

Q*100–0.004Q=28–0.01Q+0.000003Q20=(28–100)+(-0.01+0.004)Q+0.000003Q2=-72–0.006Q+0.000003Q2AztecElectronics的利潤最大化確定產(chǎn)量用二次方程公式解出

Q*AztecElectronics的利潤最大化確定價格把

Q*

代入到反需求函數(shù)P*=100–0.002(6,000)=$88AztecElectronics的利潤最大化關(guān)門決策計算6,000單位時的

AVC:AVC*=28-0.005(6,000)+0.000001(6,000)2=$34BecauseP=$88>$34=ATC,AztecshouldproduceratherthanshutdownAztecElectronics的利潤最大化計算總利潤π

=TR–TVC–TFC=

(P*

xQ*)–(AVC*

xQ*)–TFC=($88x6,000)–($34x6,000)-$270,000=$528,000-$204,000-$270,000=$54,000若人均收入下降，導致企業(yè)需求下降：P=80-0.002Q，成本不變，企業(yè)如何決策？AztecElectronics的利潤最大化ELASTICITYOFDEMANDANDPRICEMARKUPTheRuleofThumbforPricingThemarkup(P?MC)/Pisequaltominustheinverseoftheelasticityofdemand.Ifthefirm’sdemandiselastic,asin(a),themarkupissmallandthefirmhaslittlemonopolypower.Theoppositeistrueifdemandisrelativelyinelastic,asin(b).

MARKUPPRICING:SUPERMARKETSTODESIGNERJEANSAlthoughtheelasticityofmarketdemandforfoodis

small(about?1),nosinglesupermarketcanraiseits

pricesverymuchwithoutlosingcustomerstoother

stores.Theelasticityofdemandforanyonesupermarketis

oftenaslargeas?10.WefindP=MC/(1?0.1)=

MC/(0.9)=(1.11)MC.Themanagerofatypicalsupermarketshouldsetpricesabout11percentabovemarginalcost.Smallconveniencestorestypicallychargehigherpricesbecauseitscustomersaregenerallylesspricesensitive.Becausetheelasticityofdemandforaconveniencestoreisabout?5,themarkupequationimpliesthatitspricesshouldbeabout25percentabovemarginalcost.Withdesignerjeans,demandelasticitiesintherangeof?2to?3aretypical.Thismeansthatpriceshouldbe50to100percenthigherthanmarginalcost.壟斷的福利代價與競爭企業(yè)相比，壟斷者收取高于邊際成本的價格。從消費者的立場看，高價格使壟斷不合意

對企業(yè)擁有者來說，高價格使壟斷非常合意壟斷會降低經(jīng)濟效率嗎?完全競爭與壟斷的比較ComparingMonopolyandPerfectCompetitionEquilibriuminaperfectlycompetitivemarketresultsinthegreatestamountofeconomicsurplus,ortotalbenefittosociety,fromtheproductionofagoodorservice.Amonopolywillproducelessandchargeahigherpricethanwouldaperfectlycompetitiveindustryproducingthesamegood.WhatHappensIfaPerfectlyCompetitiveIndustryesaMonopoly?Inpanel(a),themarketfortabletcomputersisperfectlycompetitive,andpriceandquantityaredeterminedbytheintersectionofthedemandandsupplycurves.Inpanel(b),theperfectlycompetitivetabletcomputerindustryesamonopoly.Asaresult:1.Theindustrysupplycurveesthemonopolist’smarginalcostcurve.2.Themonopolistreducesoutputtowheremarginalrevenueequalsmarginalcost,QM.3.ThemonopolistraisesthepricefromPCtoPM.Amonopolycharges

ahigherprice,PM,andproducesa

smallerquantity,QM,thanaperfectlycompetitiveindustry,whichchargespricePCandproducesQC.Thehigherpricereducesconsumersurplusby

theareaequaltotherectangleAandthetriangleB.Someofthereductioninconsumersurplusiscapturedbythemonopolyasproducersurplus,andsomeesdeadweightloss,whichistheareaequal

totrianglesBandC.TheInefficiencyofMonopoly市場勢力與技術(shù)進步MarketPowerandTechnologicalChangeFirmsareoftenforcedtorelyontheirprofitstofinancetheresearchanddevelopmentneededfornewproducts,butsmallerfirmsdevelopanumberofnewproductsthemselvesaswell.Governmentpolicymakerscontinuetostrugglewiththeissueofwhether,onbalance,largefirmswithmarketpoweraregoodorbadfortheeconomy.AStaticViewofMonopoly:TheMarketforDrugsQuantity0CostsandRevenueDemandMarginalrevenuePriceduringpatentlifeMonopolyquantityPriceafterpatentexpiresMarginalcostCompetitivequantityADynamicViewofMonopoly:TheMarketforPCsMergers:TheTrade-offbetweenMarketPowerandEfficiencyTwofactorscancomplicateregulatinghorizontalmergers:The“market”thatfirmsareinisnotalwaysclear.Thereisthepossibilitythatthenewlymergedfirmmightbemoreefficientthanthemergingfirmswereindividually.Inpractice,thegovernmentdefinestherelevantmarketonthebasisofwhetherthereareclosesubstitutesfortheproductsbeingmadebythemergingfirms.Evenifamergedfirmismoreefficientandhaslowercosts,thatmaynotoffsettheincreasedmarketpowerofthefirmenoughtoincreaseconsumersurplusandeconomicefficiency.HorizontalmergerAmergerbetweenfirmsinthesameindustry.VerticalmergerAmergerbetweenfirmsatdifferentstagesofproduction

ofagood.Thefigureshowstheresultofallthefirmsinaperfectlycompetitiveindustrymergingtoformamonopoly.Ifcostsareunaffectedbythemerger,theresultis:PricerisesfromPCtoPM,quantityfallsfromQCtoQM,consumersurplusdeclines,andalossofeconomicefficiencyresults.If,however,themonopolyhaslowercoststhantheperfectlycompetitivefirms,asshownbythemarginalcostcurveshiftingtoMCafterthemerger,itispossiblethatthepricewillactuallydeclinefromPCtoPMergeandthatoutputwillincreasefromQCtoQMergefollowingthemerger.AMergerThatMakesConsumersBetterOffAlthoughthenewlymergedfirmhasagreatdealofmarketpower,becauseitismoreefficient,consumersarebetteroffandeconomicefficiencyisimproved.政府對壟斷的干預法規(guī)管制公有制無所作為用反托拉斯法增強競爭反托拉斯法是一些旨在抑制壟斷勢力的法規(guī)反托拉斯法允許政府用不同的途徑促進競爭阻止合并分解公司阻止企業(yè)從事減弱市場競爭的活動。管制Regulation政府可以管制壟斷者的定價Governmentmayregulatethepricesthatthemonopolycharges.價格控制（增加產(chǎn)出/減少供給）Ratecontrol平均成本定價Average-costpricing邊際成本定價Marginal-costpricingTHESOCIALCOSTSOFMONOPOLYPOWERIfleftalone,amonopolistproducesQmandchargesPm.WhenthegovernmentimposesapriceceilingofP1thefirm’saverageandmarginalrevenueareconstantandequaltoP1foroutputlevelsuptoQ1.Forlargeroutputlevels,theoriginalaverageandmarginalrevenuecurvesapply.Thenewmarginalrevenuecurveis,therefore,thedarkpurpleline,whichintersectsthemarginalcostcurveatQ1.PriceRegulationTHESOCIALCOSTSOFMONOPOLYPOWERWhenpriceisloweredtoPc,atthepointwheremarginalcostintersectsaveragerevenue,outputincreasestoitsmaximumQc.Thisistheoutputthatwouldbeproducedbyacompetitiveindustry.Loweringpricefurther,toP3reducesoutputtoQ3andcausesashortage,

Q’3?Q3.PriceRegulationRegulatingaNaturalMonopolyAnaturalmonopolythat

isnotsubjectto

governmentregulation

willchargeapriceequal

toPMandproduceQM.Ifgovernmentregulators

wanttoachieve

economicefficiency,theywillsettheregulated

priceequaltoPE,andthemonopolywill

produceQE.Unfortunately,PEis

belowaveragecost,andthemonopolywill

sufferaloss,shownbytheshadedrectangle.Becausethemonopolywillnotcontinuetoproduceinthelongrunifitsuffersaloss,governmentregulatorssetapriceequaltoaveragecost,whichisPRinthefigure.Theresultingproduction,QR,willbebelowtheefficientlevel.Localorstateregulatorycommissionsusuallysetthepricesfornaturalmonopolies.規(guī)制Regulation難以有效規(guī)制政府難以獲得壟斷企業(yè)的邊際、平均成本線；定價不能低到壟斷企業(yè)虧損（p>ac）；在確定價格下壟斷企業(yè)會提供次品，以次充好Marginal-CostPricingforaNaturalMonopoly公有制PublicOwnership政府管制的不是由私人企業(yè)經(jīng)營的自然壟斷，而是自己經(jīng)營自然壟斷。

投票機制不如利潤動機可靠。如美國公交政府制造競爭（招標）。無所作為DoingNothing如果市場失靈的程度遠遠小于政治失靈，政府就不再干預。Governmentcandonothingatallifthemarketfailureisdeemedsmallcomparedtotheimperfectionsofpublicpolicies.美國經(jīng)濟“市場失靈”的程度遠小于根植于現(xiàn)實政治制度中經(jīng)濟政策不完善所引起的“政治失靈”壟斷競爭MonopolisticCompetition壟斷競爭的特征：企業(yè)數(shù)量多而規(guī)模相對較??；產(chǎn)品相似但又彼此有差別；企業(yè)在市場上的進入和退出不受限制。星巴克（Starbucks）

的興衰星巴克：不再差異化？Starbucks:Nolongerdifferentenough?開始的繁榮1971年開出第一家店（西雅圖）1993年在東海岸開店上十年繁榮，全球38個國家經(jīng)營，共有17000家店激烈的競爭和不景氣的經(jīng)濟2008年在美國關(guān)閉600家2009年在美國關(guān)閉300多家降價克服“$4咖啡之家”印象在壟斷競爭的市場，長期維持利潤非常困難！2011年恢復盈利壟斷競爭與完全競爭、壟斷的比較壟斷競爭與完全競爭的差別：在壟斷競爭條件下，企業(yè)生產(chǎn)有差異的產(chǎn)品；壟斷競爭與壟斷的差別：在壟斷競爭條件下，企業(yè)可以自由進出市場。假設(shè)：單個企業(yè)的產(chǎn)出相對于整個市場的銷售來說數(shù)量很小，所以單個企業(yè)的價格與產(chǎn)出決策不會為市場中其他企業(yè)所察覺，企業(yè)之間獨立運作壟斷競爭下的短期利潤最大化(圖12.7)壟斷競爭下的長期均衡(圖12.8)新企業(yè)進入侵蝕利潤壟斷競爭短期均衡等同于壟斷沒有進入退出限制導致了長期均衡當每個廠商的需求曲線與長期平均成本曲線LAC相切時在均衡產(chǎn)出水平下，P=LAC

且

MR=LMC長期均衡更像一種趨勢Starbucks面臨McDonald's競爭Theeffectofentryonprice,quantity,andprofitsatStarbucks.WhatHappenstoProfitsintheLongRun?壟斷競爭廠商的處境類似于查爾斯·狄更斯在《圣誕頌》（ChristmasCarol）中描述的EbenezerScrooge遇到死神的情景。當看到自己死亡景象時，他問死神：那件事（死亡）的預兆是將來必然發(fā)生的，還是僅僅可能會發(fā)生的？利潤終結(jié)的預兆縈繞在每個廠商所有者心中并揮之不去。TheShortRunandtheLongRunforaMonopolisticallyCompetitiveFirmRelationshipbetweenPrice

andAverageTotalCostProfitandLossElasticityofDemandCurveRelationshipbetweenPrice

andMarginalCostShortRunP>MCLongRunP>MCShortRunP>MCShortRunEconomicprofitShortRunLesselasticdemandcurveorP<ATCorEconomiclossLongRunP=MCLongRunZeroeconomicprofitLongRunMoreelasticdemandcurveAbercrombie&Fitch:CantheProductBeTooDifferentiated?DidAbercrombieandFitchnarrowitstargetmarkettoomuch?Afirmwhosestrategyofproductdifferentiationsucceedswillexperienceincreasesinsame-storesales.CanItBeProfitabletoBetheHigh-PriceSeller?Becausethegreaterdemandmorethanoffsetsthehighercosts,thehhgreggstoremakesalargerprofit.MidnightSnackFigure1:Productdifferentiationshiftingthedemand

curveforamonopolisticcompetitorFigure2:“Spreadingtheoverhead”壟斷競爭與完全競爭的長期均衡比較Inpanel(b),amonopolisticallycompetitivefirmproducesatQMC,wherepriceisgreaterthanmarginalcost,andaveragetotalcostisnotataminimum.Asaresult,themonopolisticallycompetitivefirmisneitherallocativelyefficientnorproductivelyefficient.Themonopolisticallycompetitivefirmhasexcesscapacityequaltothedifferencebetweenitsprofit-maximizinglevelofoutputandtheproductivelyefficientlevelofoutput.壟斷競爭與完全競爭的長期均衡比較定價高于其邊際成本，沒有配置效率；不在平均成本最低點上生產(chǎn)，沒有生產(chǎn)效率；增加產(chǎn)量可以降低其平均成本。IsMonopolisticCompetitionInefficient?HowConsumersBenefitfromMonopolisticCompetitionConsumersbenefitfrombeingabletopurchaseaproductthatisdifferentiatedandmorecloselysuitedtotheirtastes.MarketingAlltheactivitiesnecessaryforafirmtosellaproducttoaconsumer.BrandmanagementTheactionsofafirmintendedtomaintainthedifferentiationofaproductovertime.AdvertisingIftheincreaseinrevenuethatresultsfromadvertisingisgreaterthantheincreaseincosts,thefirm’sprofitswillrise.DefendingaBrandNameAfirmcanapplyforatrademark,whichgrantslegalprotectionagainstotherfirmsusingitsproduct’sname.Legallyenforcingtrademarkscanbedifficult.U.S.firmsoftenfinditdifficulttoenforcetheirtrademarksinthecourtsofsomeforeigncountries,Product

Differentiation差異化戰(zhàn)略：品牌與廣告銷售差異化產(chǎn)品的企業(yè)：通?；ㄙM其總收益的10-20%用于廣告。總體上講，企業(yè)大約用其收益的2%作廣告。廣告AdvertisementWhenfirmsselldifferentiatedproductsandchargepricesabovemarginalcost,eachfirmhasanincentivetoadvertiseinordertoattractmorebuyerstoitsparticularproduct.品牌管理BrandManagementBrandManagementTheactionsofafirmintendedtomaintainthedifferentiationofaproductovertime.Inmanymarkets,brandnameproductscoexistwithgenericones.Firmswithbrandnamesusuallyspendmoreonadvertising,chargehigherpricesfortheproducts.Aswithadvertising,thereisdisagreementabouttheeconomicsofbrandnames…

What’sYourOpinions？0TheCritiqueofBrandNamesCriticsofbrandnamesbelieve:Brandnamescauseconsumerstoperceivedifferencesthatdonotreallyexist.Consumers’willingnesstopaymoreforbrandnamesisirrational,fosteredbyadvertising.Eliminatinggovtprotectionoftrademarkswouldreduceinfluenceofbrandnames,

resultinlowerprices.0TheDefenseofBrandNamesDefendersofbrandnamesbelieve:Brandnamesprovideinformationaboutqualitytoconsumers.信息并不在廣告的內(nèi)容中，而僅僅在于廣告的存在與其昂貴的價格中。Companieswithbrandnameshaveincentivetomaintainquality,toprotectthereputationoftheirbrandnames.0EFFECTSOFADVERTISINGTheDecisionWhethertoAdvertiseD（AR）andMRaredemandandmarginalrevenuewhenthefirmdoesn’tadvertise,andACandMCareaverageandmarginalcost.ThefirmproducesQ0andreceivesapriceP0.Itstotalprofitπ0isgivenbythegray-shadedrectangle.Ifthefirmadvertises,itsdemandandmarginalrevenuecurvesshifttotheright.Averagecostrises(toAC′)butmarginalcostremainsthesame.ThefirmnowproducesQ1(whereMR′=MC),andreceivesapriceP1.Itstotalprofit,π1,isnowlarger.HowMuchtoAdvertiseGiventhemaximizationproblem:Theprofit-maximizingo