完全競(jìng)爭市場(chǎng)上的廠商均衡教學(xué)文稿

教學(xué)目標(biāo)Objectives：了解完全競(jìng)爭(jìngzhēng)的市場(chǎng)條件掌握完全競(jìng)爭(jìngzhēng)市場(chǎng)的需求曲線和收益曲線掌握完全競(jìng)爭(jìngzhēng)市場(chǎng)的短期均衡條件掌握完全競(jìng)爭(jìngzhēng)市場(chǎng)的長期均衡條件知識(shí)點(diǎn)Knowledge：完全競(jìng)爭(jìngzhēng)的市場(chǎng)條件、完全競(jìng)爭(jìngzhēng)市場(chǎng)的需求曲線和收益曲線完全競(jìng)爭(jìngzhēng)市場(chǎng)的短期均衡和長期均衡條件技能點(diǎn)Skills：繪制完全競(jìng)爭(jìngzhēng)市場(chǎng)均衡圖第一頁，共18頁。pricetaker

advertising

marketopportunities

idealtype

advantages

shortcomings

government

NormalprofitSupernormalprofitleast-costeconomicprofitabnormalprofithomogeneousproduct

economiesofscale

industry

專業(yè)(zhuānyè)詞匯Professionalterms第二頁，共18頁。一、完全(wánquán)競(jìng)爭的含義與條件Assumptionsl

Firmsarepricetaker.l

Thereiscompletefreedomofentryintotheindustryfornewfirms.l

Allfirmsproduceanidenticalproduct.Theproductishomogeneous,sothereisnobrandingandadvertising.l

Producersandconsumershaveperfectknowledgeofthemarket.Thatis,producersarefullyawareofprices,costsandmarketopportunities.Consumersarefullyawareoftheprice,quantityandavailabilityoftheproduct.第三頁，共18頁。Nevertheless,despitethelackofreal-worldcases,themodelofperfectcompetitionplaysaveryimportantroleineconomicanalysisandpolicy.Itsmajorrelevanceisasan‘idealtype’.Manyonthepoliticalrightarguethatperfectcompetitionbringsanumberofimportantadvantages.Themodelcanthusbeusedasastandardagainstwhichtojudgetheshortcomingsofrealworldindustries.Itcanhelpgovernmenttoformulatepoliciestowardsindustry.第四頁，共18頁。一、完全競(jìng)爭的含義(hányì)與條件實(shí)現(xiàn)完全競(jìng)爭的條件包括：第一，市場(chǎng)上有許多生產(chǎn)者與消費(fèi)者，每一個(gè)生產(chǎn)者的銷售量與消費(fèi)者的購買量只占市場(chǎng)極小的份額。第二，市場(chǎng)上的產(chǎn)品是同質(zhì)的，即不存在產(chǎn)品差別(chābié)。第三，資源完全自由流動(dòng)。第四，市場(chǎng)信息是暢通的。第五頁，共18頁。一、完全競(jìng)爭(jìngzhēng)的含義與條件Theshortrunandthelongrun

l

TheshortrununderperfectcompetitionTheperiodduringwhichthereistoolittletimefornewfirmstoentertheindustry.l

ThelongrununderperfectcompetitionTheperiodoftimethatislongenoughfornewfirmstoentertheindustry.

NormalprofitTheopportunitycostofbeinginbusiness:theprofitthatcouldhavebeenearnedinthenextbestalternativebusiness.Itiscountedasacostofproduction.Supernormalprofit

(alsoknownaspureprofit,economicprofit,abnormalprofitorsimplyprofit)Theexcessoftotalprofitabovenormalprofit.第六頁，共18頁。二、完全競(jìng)爭市場(chǎng)(shìchǎng)上的需求和收益曲線0Q0Q0Q1Q2QTR完全競(jìng)爭市場(chǎng)上的需求曲線與收益曲線PPP0P0DSEd(MR=AR=P)(a)(c)(b)TR2TR1TRQ第七頁，共18頁。三、完全競(jìng)爭(jìngzhēng)市場(chǎng)上的短期均衡完全競(jìng)爭市場(chǎng)均衡圖0QEQPEd（MR=AR=P）PESMC第八頁，共18頁。三、完全競(jìng)爭市場(chǎng)(shìchǎng)上的短期均衡PESMCSACPEd（MR=AR=P）0QEQ完全競(jìng)爭市場(chǎng)廠商盈虧平衡圖廠商(chǎngshāng)獲得正常利潤(normalprofit)第九頁，共18頁。三、完全競(jìng)爭市場(chǎng)(shìchǎng)上的短期均衡廠商(chǎngshāng)獲得超額利潤(supernormalprofit)Fd（MR=AR=P）ESMCSACPPEPF0QEQ完全競(jìng)爭廠商取得超額利潤分析圖第十頁，共18頁。三、完全競(jìng)爭市場(chǎng)上的短期(duǎnqī)均衡廠商(chǎngshāng)遭受虧損SMCSACd（MR=AR=P）FEPPFPE0QEQ完全競(jìng)爭虧損廠商均衡分析圖第十一頁，共18頁。三、完全(wánquán)競(jìng)爭市場(chǎng)上的短期均衡ACBSMCSACAVCPPAPBPCd(AR=MR=PB)虧損企業(yè)經(jīng)營規(guī)模調(diào)整分析圖第十二頁，共18頁。四、完全競(jìng)爭市場(chǎng)上的長期(chángqī)均衡Revenueandcost0QuantityP=AR=MRACMCPQNORMALPROFIT第十三頁，共18頁。五、對(duì)完全競(jìng)爭市場(chǎng)(shìchǎng)的評(píng)論Inmanyindustries,firmsmayhavetobequitelargeiftheyaretoexperiencethefullpotentialeconomiesofscale.Butperfectcompetitionrequirestheretobemanyfirms.Firmsmustthereforebesmallinmostforeconomiesofscale.Onceafirmexpandssufficientlytoachieveeconomiesofscale,itwillusuallygainmarketpower.Itwillbeabletoundercutthepricesofsmallerfirms,whichwillthusbedrivenoutofbusiness.Perfectcompetitionisdestroyed.Perfectcompetitioncouldonlyexistinanyindustry,therefore,iftherewereno(orvirtuallyno)economiesofscale.第十四頁，共18頁。PerfectcompetitionandthepublicinterestThereareanumberoffeaturesofperfectcompetitionwhich,itcouldbeargued,benefitsociety:

l

Priceequalsmarginalcost,whichhasimportantimplicationsfortheallocationofresourcesbetweenalternativeproducts.l

Ifafirmbecomeslessefficientthanotherfirms,itwillmakelessthannormalprofitsandbedrivenoutofbusiness.Ifitismoreefficient,itwillearnsupernormalprofits.Thusthecompetitionbetweenfirmswillactasaspurtoefficiency.l

Similarly,thedesireforsupernormalprofit,andthedesiretoavoidloss,willencouragethedevelopmentofnewtechnology.第十五頁，共18頁。Perfectcompetitionandthepublicinterestl

Thereisnopointinadvertisingunderperfectcompetition,sinceallfirmsproduceahomogeneousproduct.ThisandtheprevioustwofactorswillleadtolowACcurves,andhencetoaneconomicaluseofthenation’sscarceresources.l

Foranygiventechnology,thefirm,inthelongrun,willproduceattheleast-costoutput.l

Theconsumergainsfromlowprices,sincenotonlyarecostskeptlow,butalsotherearenolong-runsupernormalprofitstothesecosts.l

Ifconsumertasteschange,theresultingpricechange,theresultingpricechangewillleadfirmstorespond(purelyoutofself-interest).Anincreasedconsumerdemandwillcallforthextrasupplywithonlyashort-runincreaseinprofit.第十六頁，共18頁。五、對(duì)完全競(jìng)爭市場(chǎng)(shìchǎng)的評(píng)論第一，社會(huì)供給與需求相等，使資源得到最優(yōu)配置，生產(chǎn)者的生產(chǎn)不會(huì)有不足或過剩，消費(fèi)者的需求也得到了充分滿足(mǎnzú)。第二，在長期均衡時(shí)所達(dá)到的平均成本處于最低點(diǎn)，表明可以通過完全競(jìng)爭與資源的自由流動(dòng)，使生產(chǎn)要素的效率得到