第6讲完全竞争市场.ppt

1、,完全竞争市场的价格和产量决定,市场的类型,分类标准： 1、市场中多少买方和卖方 2、产品之间有无差异 3、是否存在进入退出障碍 4、完全信息 完全竞争 完全垄断 垄断竞争 寡头垄断,The Meaning of Competition,A perfectly competitive market has the following characteristics: There are many buyers and sellers in the market. The goods offered by the various sellers are largely the same. Fir

2、ms can freely enter or exit the market.,The Meaning of Competition完全竞争的含义,As a result of its characteristics, the perfectly competitive market has the following outcomes:由于完全竞争市场具有以上特点，所以在完全竞争市场上 The actions of any single buyer or seller in the market have a negligible impact on the market price.任何单

3、个买者和卖者对于市场价格的影响都是可忽略的 Each buyer and seller takes the market price as given.任何单个买者和卖者都是市场价格的接受者,The Meaning of Competition,Buyers and sellers in competitive markets are said to be price takers. Buyers and sellers must accept the price determined by the market.,Revenue of a Competitive Firm,Total rev

4、enue for a firm is the selling price times the quantity sold. TR = (P X Q),Revenue of a Competitive Firm,Total revenue is proportional to the amount of output.,Revenue of a Competitive Firm,Average revenue tells us how much revenue a firm receives for the typical unit sold.,Revenue of a Competitive

5、Firm,In perfect competition, average revenue equals the price of the good.,Revenue of a Competitive Firm,Marginal revenue is the change in total revenue from an additional unit sold. MR =TR/ Q,Revenue of a Competitive Firm,For competitive firms, marginal revenue equals the price of the good.,Total,

6、Average, and Marginal Revenue for a Competitive Firm,Profit Maximization for the Competitive Firm,The goal of a competitive firm is to maximize profit. This means that the firm will want to produce the quantity that maximizes the difference between total revenue and total cost.,Profit Maximization:

7、A Numerical Example,二、完全竞争市场的行业需求和厂商需求,P=AR=MR,TR = (P* Q) AR=TR/Q=P MR=(TR)=(P*Q)=P,Price $ per gallon,利润 ( ) = 总收益 总成本 总收益Total Revenue (R) = P*q 总成本Total Cost (C) = C（q） 因此Therefore:,确定利润最大化的产出水平Determining the profit maximizing level of output,Q,Q1,Q*,Q2,0,MC（Q*）=P P=MR MC=MR,Profit Maximization

8、 for the Competitive Firm.完全竞争市场中企业最大化的决定,Quantity,0,ATC,AVC,Profit Maximization for the Competitive Firm,When MR MC increase Q,When MR MC decrease Q,When MR = MC Profit is maximized.,The Marginal-Cost Curve and the Firms Supply Decision.边际成本曲线和企业的短期供给曲线,Quantity,0,MC,ATC,AVC,Copyright 2001 by Harco

9、urt, Inc. All rights reserved,超额利润0,An example,机会成本,Measuring Profit in the Graph for the Competitive Firm.,Quantity,0,Price,P = AR = MR,ATC,MC,P,Q,Loss-minimizing quantity,b. A Firm with Losses,AVC,固定成本和可变成本都没有办法弥补，企业将停止营业,P,超额利润0但可以部分弥补固定成本,The Firms Short-Run Decision to Shut Down企业短期经营停止营业点,The

10、firm shuts down if the revenue it gets from producing is less than the variable cost of production.如果企业短期经营的收益弥补不了可变成本，企业将停止营业。 Shut down if TR VC Shut down if TR/Q VC/Q Shut down if P AVC,完全竞争市场的短期决策-企业的短期供给曲线,P,Q,0,MC,AC,AVC,q1,P1,P2 p3 p4 p5,q5q4q3q2,供给曲线是表示价格与供给量之间的关系，它表示在每一给定的价格下，企业愿意生产多少产品供给市场

11、。上面的分析已经导出了完全竞争市场上企业的短期供给曲线。 在完全竞争市场上企业的短期供给曲线是平均变动成本最低点以上那部分边际成本曲线。,完全竞争市场的短期决策-市场的短期供给曲线,在完全竞争市场上，市场短期供给曲线就是市场上生产这种产品的所有企业短期供给曲线的水平叠加。,P,0,Q,S1 s2 s3,S,The Firms Short-Run Decision to Shut Down,A shutdown refers to a short-run decision not to produce anything during a specific period of time becau

12、se of current market conditions. Exit refers to a long-run decision to leave the market.,The Short Run: Market Supply with a Fixed Number of Firms.,(a) Individual Firm Supply,Quantity (firm),0,Price,(b) Market Supply,Quantity (market),Price,0,Supply,MC,1.00,$2.00,100,200,1.00,$2.00,100,000,200,000,T

13、he Firms Short-Run Decision to Shut Down,The firm considers its sunk costs when deciding to exit, but ignores them when deciding whether to shut down. Sunk costs are costs that have already been committed and cannot be recovered.,The Firms Short-Run Decision to Shut Down.,Quantity,ATC,AVC,0,Costs,Th

14、e Firms Short-Run Decision to Shut Down,The portion of the marginal-cost curve that lies above average variable cost is the competitive firms short-run supply curve.,完全竞争市场厂商和行业的长期均衡,长期的含义 1、对单个企业来讲，可以调节规模 2、对于整个行业来讲可以调节企业的数量,Firm A,Quantity,0,MC,ATC,P1,Quantity,Price,0,D1,P1,Q1,A,S,1,P,Quantity,MC,

15、ATC,P,Quantity,MC,ATC,P,Firm B,Firm C,P1,P1,P2,P2,P2,P2,S2,QA,QB,QC,AVC,AVC,industry,S,P,q1,A,B,C,D,选择长期最佳规模 Choosing Optimal scale in the Long Run,Price ($ per unit of output),Output,q2,$4,LAC,E,LMC,1、P=SMC=LMC 2、P=SAC=LAC,F,1、完全竞争的长期均衡的特点,1、行业达到长期均衡时生存下来的厂商都具有最大的经济效益 2、行业达到长期均衡时，每个厂商只能赚到正常利润，超额利润为

16、零 3、行业达到长期均衡时，每个厂商提供的产量，不仅必然位于短期平均成本（SAC线最低点，而且必然位于长期LAC曲线最低点）,The Firms Long-Run Decision to Exit or Enter a Market,In the long-run, the firm exits if the revenue it would get from producing is less than its total cost. Exit if TR TC Exit if TR/Q TC/Q Exit if P ATC,完全竞争市场的长期决策,2. 市场的长期供给曲线 市场的长期供给曲

17、线， 由于市场上的企业数在变动，并且由于企业的生产规模会变动，进而单个企业的供给曲线也会变动，所以市场的长期供给曲线不再是市场上每个企业供给曲线的简单相加。 并且由于所有企业的产量发生变动时，可能会影响要素的价格， 从而导致企业的平均成本曲线的移动 。 可分为三种情况：,成本不变行业的长期供给Long-Run Supply in a Constant-Cost Industry,Output,Output,$ per unit of output,$ per unit of output,SAC,P=MC=SAC=LAC,成本递增行业的长期供给 Long-Run Supply in an In

18、creasing-Cost Industry,Output,Output,$ per unit of output,$ per unit of output,SL,P3,由于投入价格上升, 长期均衡出现 在一个较高价格处.,LAC2,B,S2,P3,SMC2,在成本递减行业的长期供给Long-Run Supply in an Decreasing-Cost Industry,Output,Output,$ per unit of output,$ per unit of output,外部经济理论揭示：当同一行业或相关行业积聚在同一地域，会给该行业的单个企业带来生产成本降低，生产效率提高的好处

19、，即外部经济，外部经济的来源可归结为如下三种： 1专业投入品供给者的涌现。 2不仅专业行业有专用设备，而且专用设备与服务也需要部门专业的人力资本供给。 3同类与相关企业在地理上的高度集中性为消费者或客户比较与选择最优的技术、服务与产品的供给，节约了决策成本与交易成本。 陆家嘴金融贸易区建立与发展的绩效 1金融板块发展势头强劲，中外金融机构及各类金融资源集聚强度得到继续提升。 2以证券为主体的资本市场功能进一步拓展，交易规模显著扩大。 3要素大市场发展迅速服务长三角，辐射全国。 4经由陆家嘴区内各类中外贸易类企业的“一般贸易”进出口额超过165亿美元，成为我国加入WTO后的重要国际接口（Inte

20、rface）和贸易平台。 5世界著名跨国公司和国际金融财团各类总部（包括区域总部、研发总部、培训总部、投资总部等）云集，机构层次高、科技含量高、人才级别高，形成我国利用外资格局中特有的“三高”现象。 6国际会展旅游与各类现代中介机构协同发展，着力培育现代服务产业制高点。 7市场开发机制促使开发公司（陆家嘴集团）与金融贸易区同步发展，带动同期区域投资规模占同期全球十大国际CBD中心区域之首。,The Firms Long-Run Decision to Exit or Enter a Market,A firm will enter the industry if such an action

21、would be profitable. Enter if TR TC Enter if TR/Q TC/Q Enter if P ATC,The Competitive Firms Long-Run Supply Curve.,Quantity,MC = Long-run S,ATC,AVC,0,Costs,The Competitive Firms Long-Run Supply Curve,The competitive firms long-run supply curve is the portion of its marginal-cost curve that lies abov

22、e average total cost.,The Competitive Firms Long-Run Supply Curve.,Quantity,MC,ATC,AVC,0,Costs,The Firms Short-Run and Long-Run Supply Curves,Short-Run Supply Curve The portion of its marginal cost curve that lies above average variable cost. Long-Run Supply Curve The marginal cost curve above the m

23、inimum point of its average total cost curve.,Measuring Profit in the Graph for the Competitive Firm.,Quantity,0,Price,P = AR = MR,ATC,MC,P,Profit-maximizing quantity,a. A Firm with Profits,Measuring Profit in the Graph for the Competitive Firm.,Quantity,0,Price,P = AR = MR,ATC,MC,P,Q,Loss-minimizin

24、g quantity,b. A Firm with Losses,AVC,Supply in a Competitive Market,Market supply equals the sum of the quantities supplied by the individual firms in the market.,The Short Run: Market Supply with a Fixed Number of Firms,For any given price, each firm supplies a quantity of output so that its margin

25、al cost equals price. The market supply curve reflects the individual firms marginal cost curves.,The Long Run: Market Supply with Entry and Exit.,(a) Firms Zero-Profit Condition,Quantity (firm),0,Price,P = minimum ATC,(b) Market Supply,Quantity (market),Price,0,Supply,MC,ATC,The Long Run: Market Su

26、pply with Entry and Exit,At the end of the process of entry and exit, firms that remain must be making zero economic profit. The process of entry & exit ends only when price and average total cost are driven to equality. Long-run equilibrium must have firms operating at their efficient scale.,Firms

27、Stay in Business with Zero Profit,Profit equals total revenue minus total cost. Total cost includes all the opportunity costs of the firm. In the zero-profit equilibrium, the firms revenue compensates the owners for the time and money they expend to keep the business going.,Increase in Demand in the

28、 Short Run,An increase in demand raises price and quantity in the short run. Firms earn profits because price now exceeds average total cost.,Increase in Demand in the Short Run.,Market,Firm,Quantity (firm),0,Price,MC,ATC,P1,Quantity (market),Price,0,D1,P1,Q1,A,S,1,Long-run supply,(a) Initial Condit

29、ion,P,Increase in Demand in the Short Run.,Market,Firm,Quantity (firm),0,Price,MC,ATC,P1,Quantity (market),Price,0,D1,P1,Q1,A,S1,Long-run supply,(b) Short-Run Response,Increase in Demand in the Short Run.,Market,Firm,Quantity (firm),0,Price,MC,ATC,P1,Quantity (market),Price,0,D1,P1,Q1,A,S1,Long-run

30、supply,(c) Long-Run Response,D2,B,Q2,P2,S2,C,Q3,Why the Long-Run Supply Curve Might Slope Upward,Some resources used in production may be available only in limited quantities. Firms may have different costs.,Marginal Firm,The marginal firm is the firm that would exit the market if the price were any

31、 lower.,Summary,Because a competitive firm is a price taker, its revenue is proportional to the amount of output it produces. The price of the good equals both the firms average revenue and its marginal revenue.,Summary,To maximize profit a firm chooses the quantity of output such that marginal reve

32、nue equals marginal cost. This is also the quantity at which price equals marginal cost. Therefore, the firms marginal cost curve is its supply curve.,Summary,In the short run when a firm cannot recover its fixed costs, the firm will choose to shut down temporarily if the price of the good is less than average vari