經(jīng)濟(jì)學(xué)原理雙語(yǔ)PPT14

1、競(jìng)爭(zhēng)市場(chǎng)上的企業(yè)經(jīng)濟(jì)學(xué)原理 N.格里高利.曼昆 著14Firms in Competitive Markets本章我們將探索這些問(wèn)題的答案：什么是完全競(jìng)爭(zhēng)市場(chǎng)？ 什么是邊際收益？它和總收益與平均收益有什么關(guān)系？競(jìng)爭(zhēng)企業(yè)如何決定利潤(rùn)最大化的產(chǎn)量？短期內(nèi)，競(jìng)爭(zhēng)企業(yè)何時(shí)會(huì)選擇停業(yè)？長(zhǎng)期內(nèi)，競(jìng)爭(zhēng)企業(yè)何時(shí)會(huì)選擇退出市場(chǎng)？短期的市場(chǎng)供給曲線是什么形狀？長(zhǎng)期的呢？12介紹：一個(gè)故事你畢業(yè)三年之后，你開(kāi)始自己做生意你必須決定生產(chǎn)多少，定怎樣的價(jià)格，以及雇傭多少工人等等哪些因素會(huì)影響這些決策？你的成本（前一章我們學(xué)過(guò)的內(nèi)容）你面臨怎樣的競(jìng)爭(zhēng)我們開(kāi)始在完全競(jìng)爭(zhēng)市場(chǎng)中研究企業(yè)的行為03競(jìng)爭(zhēng)的含義The Meanin

2、g of Competition完全競(jìng)爭(zhēng)市場(chǎng)具有下列特征: A perfectly competitive market has the following characteristics:市場(chǎng)上有許多買(mǎi)者和許多賣(mài)者There are many buyers and sellers in the market.各個(gè)賣(mài)者提供的物品大體上是相同的The goods offered by the various sellers are largely the same.企業(yè)能夠自由地進(jìn)入或退出市場(chǎng) Firms can freely enter or exit the market.0競(jìng)爭(zhēng)的含義The

3、 Meaning of Competition這些特征，使得完全競(jìng)爭(zhēng)市場(chǎng)具有如下結(jié)果：As a result of its characteristics, the perfectly competitive market has the following outcomes:The actions of any single buyer or seller in the market have a negligible impact on the market price.Each buyer and seller takes the market price as given.任何一個(gè)買(mǎi)者

4、或賣(mài)者的行動(dòng)對(duì)市場(chǎng)價(jià)格的影響都可以忽略不計(jì)。每一個(gè)買(mǎi)者和賣(mài)者都接受市場(chǎng)決定的價(jià)格。競(jìng)爭(zhēng)的含義The Meaning of Competition競(jìng)爭(zhēng)市場(chǎng)中的買(mǎi)者和賣(mài)者被稱(chēng)為價(jià)格接受者。Buyers and sellers in competitive markets are said to be price takers.完全競(jìng)爭(zhēng)廠商的需求曲線1.完全競(jìng)爭(zhēng)市場(chǎng)的需求曲線（1）完全競(jìng)爭(zhēng)市場(chǎng)的價(jià)格為P0。由整個(gè)行業(yè)的供給和需求曲線的交點(diǎn)所決定。P0一旦確定，個(gè)別廠商和消費(fèi)者只能接受，而不能影響。P0QDSEP完全競(jìng)爭(zhēng)市場(chǎng)上，企業(yè)需求曲線是與橫軸平行的線。市場(chǎng)中對(duì)個(gè)別廠商的需求曲線是一條從既定市場(chǎng)價(jià)

5、格出發(fā)的平行線。2.完全競(jìng)爭(zhēng)市場(chǎng)單個(gè)廠商面對(duì)的需求曲線P0ddQDSEP競(jìng)爭(zhēng)的含義The Meaning of Competition企業(yè)的總收益 (TR)是銷(xiāo)售價(jià)格乘以銷(xiāo)售量。Total revenue for a firm is the selling price times the quantity sold.TR = P x Q收益全部收入，包括成本和利潤(rùn)。收益是出售產(chǎn)品所得到的錢(qián)，而不是所賺取的錢(qián)。 9競(jìng)爭(zhēng)企業(yè)的收益Revenue of a Competitive Firm平均收益(AR)告訴我們一個(gè)企業(yè)從每一典型單位的銷(xiāo)售中得到多少收益。Average revenuetells u

6、s how much revenue a firm receives for the typical unit sold.0競(jìng)爭(zhēng)企業(yè)的收益Revenue of a Competitive Firm對(duì)所有企業(yè)來(lái)說(shuō)，平均收益等于物品的價(jià)格。For allfirms, average revenue equals the price of the good.Average revenue =Total revenue /Quantity =(Price* Quantity)/Quantity = Price競(jìng)爭(zhēng)企業(yè)的收益Revenue of a Competitive Firm邊際收益(MR):增加

7、一單位銷(xiāo)售量引起的總收益的的變動(dòng)。Marginal revenueis the change in total revenue from an additional unit sold.主動(dòng)學(xué)習(xí) 1 計(jì)算 TR, AR, MR12 完成下面這張表格$50$105$40$104$103$102$10$101n/a$100TRPQMRAR$100主動(dòng)學(xué)習(xí) 1 參考答案13 完成下面這張表格$50$105$40$104$103$10$10$10$10$102$10$101n/a$30$20$10$0$100TR = P x QPQTRQMR =TRQAR =$10$10$10$10$10注意MR =

8、 P0FIRMS IN COMPETITIVE MARKETS14對(duì)一個(gè)競(jìng)爭(zhēng)企業(yè)而言： MR = P 一個(gè)競(jìng)爭(zhēng)企業(yè)能夠增加它的產(chǎn)量，而不影響市場(chǎng)價(jià)格因此，每單位產(chǎn)量增加使收益增加P， 也就是 MR = P MR = P 僅對(duì)競(jìng)爭(zhēng)市場(chǎng)上的企業(yè)成立0競(jìng)爭(zhēng)企業(yè)的總收益、平均收益和邊際收益Total, Average, and Marginal Revenue for a Competitive Firm競(jìng)爭(zhēng)企業(yè)的利潤(rùn)最大化Profit Maximization for the Competitive Firm競(jìng)爭(zhēng)企業(yè)的目標(biāo)是利潤(rùn)最大化。The goal of a competitive firm i

9、s to maximize profit.這意味著企業(yè)將生產(chǎn)使總收益和總成本之差最大的產(chǎn)量。This means that the firm will want to produce the quantity that maximizes the difference between total revenue and total cost .FIRMS IN COMPETITIVE MARKETS17競(jìng)爭(zhēng)企業(yè)的利潤(rùn)最大化Profit Maximization for the Competitive Firm企業(yè)利潤(rùn)最大化的產(chǎn)量是多少？ 回答問(wèn)題，我們需要“考慮邊際量 ”如果產(chǎn)量增加一單位，那

10、么收益增加MR， 成本增加MC 如果 MR MC，那增加產(chǎn)量會(huì)提高利潤(rùn)如果MR MC，那增加產(chǎn)量會(huì)提高利潤(rùn)57751$5101010102 024$6121086$4$10如果MR MC，那降低產(chǎn)量會(huì)提高利潤(rùn)0FIRMS IN COMPETITIVE MARKETS19P1MR競(jìng)爭(zhēng)企業(yè)的利潤(rùn)最大化Profit Maximization for the Competitive Firm在Qa, MC MR，因此降低產(chǎn)量會(huì)提高利潤(rùn)在Q1, MC = MR，改變產(chǎn)量會(huì)減少利潤(rùn)Q成本MCQ1QaQb規(guī)則： MR = MC 是利潤(rùn)最大化的產(chǎn)量0利潤(rùn)最大化的數(shù)學(xué)推導(dǎo)表示廠商的利潤(rùn)：=TR-TC 短期：價(jià)格

11、既定，不變要素投入量固定。廠商只能變動(dòng)可變要素，來(lái)調(diào)整產(chǎn)量，實(shí)現(xiàn)MR=MC的利潤(rùn)最大化均衡條件。完全競(jìng)爭(zhēng)市場(chǎng)的短期均衡和供給曲線 短期內(nèi)，完全競(jìng)爭(zhēng)市場(chǎng)，供求作用形成價(jià)格，可能高于、等于、低于廠商的平均成本，廠商可能處于盈利、盈虧平衡或虧損等不同狀態(tài)。 廠商均衡：當(dāng)廠商的生產(chǎn)水平保持不變，既不擴(kuò)大也不縮小時(shí)，廠商處于均衡狀態(tài)。 1.完全競(jìng)爭(zhēng)廠商的短期均衡 利潤(rùn)最大化原則：MR=MCE點(diǎn)為廠商決策點(diǎn)決定產(chǎn)量OM，價(jià)格ON。PQSACSMCMNGEKOddAR=MR=P超額利潤(rùn)GKEN（綠色部分）TR=OMENTC=OMKG （1）行業(yè)供給小于需求，價(jià)格水平比較高。P=ARSAC，廠商處于盈利狀態(tài)。

12、 （2）行業(yè)供給大于需求，價(jià)格水平比較低利潤(rùn)最大化原則MR=MCE點(diǎn)為廠商決策點(diǎn)，決定產(chǎn)量OM，價(jià)格ON。PQSACSMCdd（AR=MR=P）EMONKGTR=OMENTC=OMKG存在虧損GKEN（紅色部分）（3）廠商需求曲線切于SAC最低點(diǎn)P=AR=SAC，廠商的經(jīng)濟(jì)利潤(rùn)恰好為零,處于盈虧平衡狀態(tài) PQSACSMCdd（AR=MR=P）EMONE1：停止?fàn)I業(yè)點(diǎn)AVCPQSACSMCdd（AR=MR =P）E1MOP1EP0完全競(jìng)爭(zhēng)市場(chǎng)，廠商在市場(chǎng)價(jià)格低于平均成本的最低點(diǎn)但高于平均可變成本最低點(diǎn)進(jìn)行生產(chǎn)時(shí)，該廠商將：A處于利潤(rùn)最大化狀態(tài)B處于虧損狀態(tài)C獲得正常利潤(rùn)D仍將繼續(xù)生產(chǎn)2.完全競(jìng)爭(zhēng)

13、廠商的短期供給曲線 完全競(jìng)爭(zhēng)市場(chǎng)，廠商不會(huì)影響價(jià)格；廠商的邊際收益等于價(jià)格。廠商短期利潤(rùn)最大化的產(chǎn)量： P=SMC（Q）為了獲得短期最大利潤(rùn)，最優(yōu)產(chǎn)量確定在價(jià)格和邊際成本相等。在每一短期均衡點(diǎn)，廠商的產(chǎn)量與價(jià)格之間存在一種對(duì)應(yīng)關(guān)系。 完全競(jìng)爭(zhēng)廠商短期供給曲線的推導(dǎo)(d1)AR1=MR1=P1(d2)AR2=MR2=P2(d3)AR3=MR3=P3(d4)AR4=MR4=P4(d5)AR5=MR5=P5QOP.R.CP1P2P3P4P5E1E2 E3 E4E5Q1Q2Q4Q5SMCSACAVCQ3PSQOSMCE1E2E3E4Q4Q3Q1Q2短期中完全競(jìng)爭(zhēng)廠商的供給曲線是MC在AVC之上部分。

14、FIRMS IN COMPETITIVE MARKETS28停止?fàn)I業(yè)與退出市場(chǎng)停止?fàn)I業(yè)： 由于市場(chǎng)條件，企業(yè)決定在某個(gè)特定時(shí)間不生產(chǎn)任何東西的短期決策退出市場(chǎng)： 企業(yè)離開(kāi)市場(chǎng)的長(zhǎng)期決策一個(gè)重要的區(qū)別： 如果在短期內(nèi)停止?fàn)I業(yè)，仍必須支付固定成本如果在長(zhǎng)期內(nèi)退出市場(chǎng)，沒(méi)有任何成本0FIRMS IN COMPETITIVE MARKETS29企業(yè)的短期決策：停止?fàn)I業(yè)停止?fàn)I業(yè)的成本：收益損失= TR停止?fàn)I業(yè)的收益：節(jié)約成本 = VC (企業(yè)仍然必須支付 FC)因此，如果 TR VC ，停止?fàn)I業(yè)等式兩邊除以產(chǎn)量：TR/Q VC/Q因此，企業(yè)停止?fàn)I業(yè)的標(biāo)準(zhǔn)是：如果 P AVC，那企業(yè)將產(chǎn)量定在 P = M

15、C 的地方如果P 100，廠商處于規(guī)模不經(jīng)濟(jì)階段。因?yàn)槠洚a(chǎn)量處于成本最低點(diǎn)右邊。企業(yè)進(jìn)入或退出市場(chǎng)的長(zhǎng)期決策The Firms Long-Run Decision toExit or Enter a Market在長(zhǎng)期，如果從生產(chǎn)中得到的收益將小于它的總成本，企業(yè)就退出。In the long-run, the firm exits if the revenueit would get from producing is less than itstotal cost.如果TR TC，退出如果TR/Q TC/Q，退出如果P TC ，進(jìn)入 如果TR/Q TC/Q ，進(jìn)入如果P ATC，進(jìn)入企業(yè)進(jìn)

16、入或退出市場(chǎng)的長(zhǎng)期決策The Firms Long-Run Decision toExit or Enter a MarketQuantityMC = Long-run SATCAVC0CostsFirm enters if P ATCFirm exitsif P ATC競(jìng)爭(zhēng)企業(yè)的長(zhǎng)期供給曲線The Competitive Firms Long-Run Supply Curve.QuantityMCATCAVC0CostsFirms long-run supply curve競(jìng)爭(zhēng)企業(yè)的長(zhǎng)期供給曲線The Competitive Firms Long-Run Supply Curve競(jìng)爭(zhēng)企業(yè)的長(zhǎng)

17、期供給曲線是邊際成本曲線位于平均總成本曲線之上的那一部分。The competitive firms long-run supply curve is the portion of its marginal-cost curve that lies above average total cost.企業(yè)的短期和長(zhǎng)期供給曲線The Firms Short-Run andLong-Run Supply Curves短期供給曲線Short-Run Supply Curve邊際成本曲線在平均可變成本曲線以上的那一部分。The portion of its marginal cost curve tha

18、t liesabove average variable cost.長(zhǎng)期供給曲線Long-Run Supply Curve邊際成本曲線在平均總成本曲線最低點(diǎn)以上的那一部分。The marginal cost curve above the minimumpoint of its average total cost curve.長(zhǎng)期：有進(jìn)入和退出的市場(chǎng)供給The Long Run: Market Supplywith Entry and Exit假定所有企業(yè)和潛在企業(yè)都有同樣的成本曲線。Suppose that all firms and all potential firms have th

19、e same cost curves.企業(yè)將進(jìn)入或退出市場(chǎng)，直到利潤(rùn)被推向零。Firms will enter or exit the market until profit is driven to zero.只有當(dāng)價(jià)格與平均總成本被推向相等時(shí)，進(jìn)入與退出過(guò)程才結(jié)束。The process of entry & exit ends only when price and average total cost are driven to equality.長(zhǎng)期：有進(jìn)入和退出的市場(chǎng)供給The Long Run: Market Supplywith Entry and Exit因?yàn)閮r(jià)格既要等于邊際

20、成本又要等于平均總成本，因此企業(yè)必然在其有效率規(guī)模處生產(chǎn)。Because price is to equal both marginal cost and average cost, firms must operate at the irefficient scale.在長(zhǎng)期，價(jià)格等于平均總成本的最小值。In the long run, price equals the minimum of average total cost.長(zhǎng)期市場(chǎng)供給曲線是一條在此價(jià)格上的水平線The long-run market supply curve is horizontal at this price.長(zhǎng)

21、期：有進(jìn)入和退出的市場(chǎng)供給The Long Run: Market Supplywith Entry and Exit.(a) Firms Zero-Profit ConditionQuantity(firm)0Price P =minimum ATC(b) Market SupplyQuantity(market)Price0SupplyMCATC需求的增加在短期內(nèi)和長(zhǎng)期內(nèi)的影響Increase in Demand in the ShortRun and in the Long Run因?yàn)槠髽I(yè)在長(zhǎng)期可以進(jìn)入和退出，而在短期卻不能，因此市場(chǎng)對(duì)于需求變動(dòng)的反應(yīng)依賴(lài)于時(shí)間范圍。Because fi

22、rms can enter and exit in the long run but not in the short run, there sponse of a market to a change in demand depends on the time horizon.需求的增加在短期內(nèi)和長(zhǎng)期內(nèi)的影響Increase in Demand in the Short Runand in the Long RunMarketFirmQuantity(firm)0PriceMCATCP1Quantity(market)Price0D1P1Q1AS1Long-runsupply(a) Init

23、ial ConditionPD2需求的增加在短期內(nèi)和長(zhǎng)期內(nèi)的影響Increase in Demand in the Short Runand in the Long RunMarketFirmQuantity(firm)0PriceMCATCP1Quantity(market)Price0D1P1Q1AS1Long-runsupply(b) Short-Run ResponseQ2BP2P2Profit需求的增加在短期內(nèi)和長(zhǎng)期內(nèi)的影響Increase in Demand in the ShortRun and in the Long Run需求的增加在短期內(nèi)提高價(jià)格并增加數(shù)量。An incre

24、ase in demand raises price and quantity in the short run.企業(yè)賺到正利潤(rùn)，因?yàn)閮r(jià)格現(xiàn)在高于平均總成本。Firms earn profits because price now exceeds average total cost.需求的增加在短期內(nèi)和長(zhǎng)期內(nèi)的影響Increase in Demand in the Short Runand in the Long RunMarketFirmQuantity(firm)0PriceMCATCP1Quantity(market)Price0D1P1Q1AS1Long-runsupply(c) L

25、ong-Run ResponseD2BQ2P2S2CQ3需求的增加在短期內(nèi)和長(zhǎng)期內(nèi)的影響Increase in Demand in the ShortRun and in the Long Run隨著時(shí)間的推移，這個(gè)市場(chǎng)的利潤(rùn)鼓勵(lì)新企業(yè)進(jìn)入。Over time, the profit in this market encourages newfirms to enter.隨著企業(yè)數(shù)量和供給的增加，市場(chǎng)價(jià)格下降。As the number of firms grows, the price falls.最后，價(jià)格又向下回到最低平均總成本，利潤(rùn)是零，而且，企業(yè)停止進(jìn)入。Eventually, th

26、e price is driven back down to theminimum of average total cost, profits are zero, andfirms stop entering.每個(gè)企業(yè)仍然在其有效率規(guī)模處生產(chǎn)，但是，企業(yè)的數(shù)目、市場(chǎng)的產(chǎn)量和銷(xiāo)售量都提高了。Each firm is again producing at its efficient scale, butthe number of firms, the quantity produced and soldare both higher.為什么企業(yè)獲得零利潤(rùn)還在經(jīng)營(yíng)？Why Firms Stay i

27、n Businesswith Zero Profit?利潤(rùn)等于總收益減總成本。Profit equals total revenue minus total cost.總成本包括企業(yè)的所有機(jī)會(huì)成本。Total cost includes all the opportunity costs of the firm.在零利潤(rùn)均衡時(shí)，企業(yè)的收益應(yīng)該補(bǔ)償所有者維持經(jīng)營(yíng)的時(shí)間和金錢(qián)。In the zero-profit equilibrium, the firms revenue compensates the owners for the time and money they expend to k

28、eep the business going.經(jīng)濟(jì)利潤(rùn)不同于會(huì)計(jì)利潤(rùn)。Economic profits differ from accounting profits.為什么長(zhǎng)期供給曲線會(huì)向右上方傾斜Why the Long-Run Supply CurveMight Slope Upward一些用于生產(chǎn)的資源數(shù)量可能是有限的。Some resources used in productionmay be available only in limitedquantities.企業(yè)可能有不同的成本。Firms may have different costs.邊際企業(yè)Marginal Firm邊

29、際企業(yè)是如果價(jià)格稍有下降就退出市場(chǎng)的企業(yè)。The marginal firm is the firmthat would exit the market if the price were any lower.總結(jié)Summary由于競(jìng)爭(zhēng)企業(yè)是價(jià)格接受者，所以它的收益與產(chǎn)量是同比例的。Because a competitive firm is a price taker, its revenue is proportional to the amount of output it produces.物品的價(jià)格等于企業(yè)的平均收益和邊際收益。The price of the good equals both the firms average revenue and its margin