经济学原理双语PPT14

1、竞争市场上的企业经济学原理 N.格里高利.曼昆 著14Firms in Competitive Markets本章我们将探索这些问题的答案：什么是完全竞争市场？ 什么是边际收益？它和总收益与平均收益有什么关系？竞争企业如何决定利润最大化的产量？短期内，竞争企业何时会选择停业？长期内，竞争企业何时会选择退出市场？短期的市场供给曲线是什么形状？长期的呢？12介绍：一个故事你毕业三年之后，你开始自己做生意你必须决定生产多少，定怎样的价格，以及雇佣多少工人等等哪些因素会影响这些决策？你的成本（前一章我们学过的内容）你面临怎样的竞争我们开始在完全竞争市场中研究企业的行为03竞争的含义The Meanin

2、g of Competition完全竞争市场具有下列特征: A perfectly competitive market has the following characteristics:市场上有许多买者和许多卖者There are many buyers and sellers in the market.各个卖者提供的物品大体上是相同的The goods offered by the various sellers are largely the same.企业能够自由地进入或退出市场 Firms can freely enter or exit the market.0竞争的含义The

3、 Meaning of Competition这些特征，使得完全竞争市场具有如下结果：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.任何一个买者

4、或卖者的行动对市场价格的影响都可以忽略不计。每一个买者和卖者都接受市场决定的价格。竞争的含义The Meaning of Competition竞争市场中的买者和卖者被称为价格接受者。Buyers and sellers in competitive markets are said to be price takers.完全竞争厂商的需求曲线1.完全竞争市场的需求曲线（1）完全竞争市场的价格为P0。由整个行业的供给和需求曲线的交点所决定。P0一旦确定，个别厂商和消费者只能接受，而不能影响。P0QDSEP完全竞争市场上，企业需求曲线是与横轴平行的线。市场中对个别厂商的需求曲线是一条从既定市场价

5、格出发的平行线。2.完全竞争市场单个厂商面对的需求曲线P0ddQDSEP竞争的含义The Meaning of Competition企业的总收益 (TR)是销售价格乘以销售量。Total revenue for a firm is the selling price times the quantity sold.TR = P x Q收益全部收入，包括成本和利润。收益是出售产品所得到的钱，而不是所赚取的钱。 9竞争企业的收益Revenue of a Competitive Firm平均收益(AR)告诉我们一个企业从每一典型单位的销售中得到多少收益。Average revenuetells u

6、s how much revenue a firm receives for the typical unit sold.0竞争企业的收益Revenue of a Competitive Firm对所有企业来说，平均收益等于物品的价格。For allfirms, average revenue equals the price of the good.Average revenue =Total revenue /Quantity =(Price* Quantity)/Quantity = Price竞争企业的收益Revenue of a Competitive Firm边际收益(MR):增加

7、一单位销售量引起的总收益的的变动。Marginal revenueis the change in total revenue from an additional unit sold.主动学习 1 计算 TR, AR, MR12 完成下面这张表格$50$105$40$104$103$102$10$101n/a$100TRPQMRAR$100主动学习 1 参考答案13 完成下面这张表格$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对一个竞争企业而言： MR = P 一个竞争企业能够增加它的产量，而不影响市场价格因此，每单位产量增加使收益增加P， 也就是 MR = P MR = P 仅对竞争市场上的企业成立0竞争企业的总收益、平均收益和边际收益Total, Average, and Marginal Revenue for a Competitive Firm竞争企业的利润最大化Profit Maximization for the Competitive Firm竞争企业的目标是利润最大化。The goal of a competitive firm i

9、s to maximize profit.这意味着企业将生产使总收益和总成本之差最大的产量。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竞争企业的利润最大化Profit Maximization for the Competitive Firm企业利润最大化的产量是多少？ 回答问题，我们需要“考虑边际量 ”如果产量增加一单位，那

10、么收益增加MR， 成本增加MC 如果 MR MC，那增加产量会提高利润如果MR MC，那增加产量会提高利润57751$5101010102 024$6121086$4$10如果MR MC，那降低产量会提高利润0FIRMS IN COMPETITIVE MARKETS19P1MR竞争企业的利润最大化Profit Maximization for the Competitive Firm在Qa, MC MR，因此降低产量会提高利润在Q1, MC = MR，改变产量会减少利润Q成本MCQ1QaQb规则： MR = MC 是利润最大化的产量0利润最大化的数学推导表示厂商的利润：=TR-TC 短期：价格

11、既定，不变要素投入量固定。厂商只能变动可变要素，来调整产量，实现MR=MC的利润最大化均衡条件。完全竞争市场的短期均衡和供给曲线 短期内，完全竞争市场，供求作用形成价格，可能高于、等于、低于厂商的平均成本，厂商可能处于盈利、盈亏平衡或亏损等不同状态。 厂商均衡：当厂商的生产水平保持不变，既不扩大也不缩小时，厂商处于均衡状态。 1.完全竞争厂商的短期均衡 利润最大化原则：MR=MCE点为厂商决策点决定产量OM，价格ON。PQSACSMCMNGEKOddAR=MR=P超额利润GKEN（绿色部分）TR=OMENTC=OMKG （1）行业供给小于需求，价格水平比较高。P=ARSAC，厂商处于盈利状态。

12、 （2）行业供给大于需求，价格水平比较低利润最大化原则MR=MCE点为厂商决策点，决定产量OM，价格ON。PQSACSMCdd（AR=MR=P）EMONKGTR=OMENTC=OMKG存在亏损GKEN（红色部分）（3）厂商需求曲线切于SAC最低点P=AR=SAC，厂商的经济利润恰好为零,处于盈亏平衡状态 PQSACSMCdd（AR=MR=P）EMONE1：停止营业点AVCPQSACSMCdd（AR=MR =P）E1MOP1EP0完全竞争市场，厂商在市场价格低于平均成本的最低点但高于平均可变成本最低点进行生产时，该厂商将：A处于利润最大化状态B处于亏损状态C获得正常利润D仍将继续生产2.完全竞争

13、厂商的短期供给曲线 完全竞争市场，厂商不会影响价格；厂商的边际收益等于价格。厂商短期利润最大化的产量： P=SMC（Q）为了获得短期最大利润，最优产量确定在价格和边际成本相等。在每一短期均衡点，厂商的产量与价格之间存在一种对应关系。 完全竞争厂商短期供给曲线的推导(d1)AR1=MR1=P1(d2)AR2=MR2=P2(d3)AR3=MR3=P3(d4)AR4=MR4=P4(d5)AR5=MR5=P5QOP.R.CP1P2P3P4P5E1E2 E3 E4E5Q1Q2Q4Q5SMCSACAVCQ3PSQOSMCE1E2E3E4Q4Q3Q1Q2短期中完全竞争厂商的供给曲线是MC在AVC之上部分。

14、FIRMS IN COMPETITIVE MARKETS28停止营业与退出市场停止营业： 由于市场条件，企业决定在某个特定时间不生产任何东西的短期决策退出市场： 企业离开市场的长期决策一个重要的区别： 如果在短期内停止营业，仍必须支付固定成本如果在长期内退出市场，没有任何成本0FIRMS IN COMPETITIVE MARKETS29企业的短期决策：停止营业停止营业的成本：收益损失= TR停止营业的收益：节约成本 = VC (企业仍然必须支付 FC)因此，如果 TR VC ，停止营业等式两边除以产量：TR/Q VC/Q因此，企业停止营业的标准是：如果 P AVC，那企业将产量定在 P = M

15、C 的地方如果P 100，厂商处于规模不经济阶段。因为其产量处于成本最低点右边。企业进入或退出市场的长期决策The Firms Long-Run Decision toExit or Enter a Market在长期，如果从生产中得到的收益将小于它的总成本，企业就退出。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 ，进入 如果TR/Q TC/Q ，进入如果P ATC，进入企业进

16、入或退出市场的长期决策The Firms Long-Run Decision toExit or Enter a MarketQuantityMC = Long-run SATCAVC0CostsFirm enters if P ATCFirm exitsif P ATC竞争企业的长期供给曲线The Competitive Firms Long-Run Supply Curve.QuantityMCATCAVC0CostsFirms long-run supply curve竞争企业的长期供给曲线The Competitive Firms Long-Run Supply Curve竞争企业的长

17、期供给曲线是边际成本曲线位于平均总成本曲线之上的那一部分。The competitive firms long-run supply curve is the portion of its marginal-cost curve that lies above average total cost.企业的短期和长期供给曲线The Firms Short-Run andLong-Run Supply Curves短期供给曲线Short-Run Supply Curve边际成本曲线在平均可变成本曲线以上的那一部分。The portion of its marginal cost curve tha

18、t liesabove average variable cost.长期供给曲线Long-Run Supply Curve边际成本曲线在平均总成本曲线最低点以上的那一部分。The marginal cost curve above the minimumpoint of its average total cost curve.长期：有进入和退出的市场供给The Long Run: Market Supplywith Entry and Exit假定所有企业和潜在企业都有同样的成本曲线。Suppose that all firms and all potential firms have th

19、e same cost curves.企业将进入或退出市场，直到利润被推向零。Firms will enter or exit the market until profit is driven to zero.只有当价格与平均总成本被推向相等时，进入与退出过程才结束。The process of entry & exit ends only when price and average total cost are driven to equality.长期：有进入和退出的市场供给The Long Run: Market Supplywith Entry and Exit因为价格既要等于边际

20、成本又要等于平均总成本，因此企业必然在其有效率规模处生产。Because price is to equal both marginal cost and average cost, firms must operate at the irefficient scale.在长期，价格等于平均总成本的最小值。In the long run, price equals the minimum of average total cost.长期市场供给曲线是一条在此价格上的水平线The long-run market supply curve is horizontal at this price.长

21、期：有进入和退出的市场供给The Long Run: Market Supplywith Entry and Exit.(a) Firms Zero-Profit ConditionQuantity(firm)0Price P =minimum ATC(b) Market SupplyQuantity(market)Price0SupplyMCATC需求的增加在短期内和长期内的影响Increase in Demand in the ShortRun and in the Long Run因为企业在长期可以进入和退出，而在短期却不能，因此市场对于需求变动的反应依赖于时间范围。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.需求的增加在短期内和长期内的影响Increase in Demand in the Short Runand in the Long RunMarketFirmQuantity(firm)0PriceMCATCP1Quantity(market)Price0D1P1Q1AS1Long-runsupply(a) Init

23、ial ConditionPD2需求的增加在短期内和长期内的影响Increase in Demand in the Short Runand in the Long RunMarketFirmQuantity(firm)0PriceMCATCP1Quantity(market)Price0D1P1Q1AS1Long-runsupply(b) Short-Run ResponseQ2BP2P2Profit需求的增加在短期内和长期内的影响Increase in Demand in the ShortRun and in the Long Run需求的增加在短期内提高价格并增加数量。An incre

24、ase in demand raises price and quantity in the short run.企业赚到正利润，因为价格现在高于平均总成本。Firms earn profits because price now exceeds average total cost.需求的增加在短期内和长期内的影响Increase in Demand in the Short Runand in the Long RunMarketFirmQuantity(firm)0PriceMCATCP1Quantity(market)Price0D1P1Q1AS1Long-runsupply(c) L

25、ong-Run ResponseD2BQ2P2S2CQ3需求的增加在短期内和长期内的影响Increase in Demand in the ShortRun and in the Long Run随着时间的推移，这个市场的利润鼓励新企业进入。Over time, the profit in this market encourages newfirms to enter.随着企业数量和供给的增加，市场价格下降。As the number of firms grows, the price falls.最后，价格又向下回到最低平均总成本，利润是零，而且，企业停止进入。Eventually, th

26、e price is driven back down to theminimum of average total cost, profits are zero, andfirms stop entering.每个企业仍然在其有效率规模处生产，但是，企业的数目、市场的产量和销售量都提高了。Each firm is again producing at its efficient scale, butthe number of firms, the quantity produced and soldare both higher.为什么企业获得零利润还在经营？Why Firms Stay i

27、n Businesswith Zero Profit?利润等于总收益减总成本。Profit equals total revenue minus total cost.总成本包括企业的所有机会成本。Total cost includes all the opportunity costs of the firm.在零利润均衡时，企业的收益应该补偿所有者维持经营的时间和金钱。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.经济利润不同于会计利润。Economic profits differ from accounting profits.为什么长期供给曲线会向右上方倾斜Why the Long-Run Supply CurveMight Slope Upward一些用于生产的资源数量可能是有限的。Some resources used in productionmay be available only in limitedquantities.企业可能有不同的成本。Firms may have different costs.边际企业Marginal Firm边

29、际企业是如果价格稍有下降就退出市场的企业。The marginal firm is the firmthat would exit the market if the price were any lower.总结Summary由于竞争企业是价格接受者，所以它的收益与产量是同比例的。Because a competitive firm is a price taker, its revenue is proportional to the amount of output it produces.物品的价格等于企业的平均收益和边际收益。The price of the good equals both the firms average revenue and its margin