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Chapter 8

Chapter 8. Profit Maximization and Competitive Supply 利润最大化与竞争性供给. Topics to be Discussed. Perfectly Competitive Markets 完全竞争市场 Profit Maximization 利润最大化 Marginal Revenue, Marginal Cost, and Profit Maximization 边际收益、边际成本和利润最大化 Choosing Output in the Short-Run 选择短期产量.

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Chapter 8

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  1. Chapter 8 Profit Maximization and Competitive Supply 利润最大化与竞争性供给

  2. Topics to be Discussed • Perfectly Competitive Markets 完全竞争市场 • Profit Maximization 利润最大化 • Marginal Revenue, Marginal Cost, and Profit Maximization 边际收益、边际成本和利润最大化 • Choosing Output in the Short-Run 选择短期产量 Chapter 1

  3. Topics to be Discussed • The Competitive Firm’s Short-Run Supply Curve 竞争性厂商短期供给曲线 • Short-Run Market Supply 短期市场供给曲线 • Choosing Output in the Long-Run 选择长期产量 • The Industry’s Long-Run Supply Curve 厂商的长期供给曲线 Chapter 1

  4. Perfectly Competitive Markets • Characteristics of Perfectly Competitive Markets 完全竞争市场的特征 1) Price taking 既定价格承担 2) Product homogeneity 产品同质 3) Free entry and exit 自由进入和退出市场 Chapter 1

  5. Price Taking 既定价格承担 • The individual firm sells a very small share of the total market output and, therefore, cannot influence market price. 每个厂商出售的产量占行业产量的比重足够小以至于个别厂商的决策对市场价格不产生影响 • The individual consumer buys too small a share of industry output to have any impact on market price. 每个消费者的购买量占行业产量的比重业足够小以至于个别消费者对市场价格没有影响 Chapter 1

  6. Product Homogeneity 产品同质 • The products of all firms are perfect substitutes. 不同厂家生产的产品是完全替代品 • Examples • Agricultural products, oil, copper, iron, lumber 农产品；原油；铜；铁；木材 Chapter 1

  7. Perfectly Competitive Markets • Free Entry and Exit 自由进入和退出市场 • Buyers can easily switch from one supplier to another. 购买者可以自如地从一个供应商转向另外一个供应商 • Suppliers can easily enter or exit a market. 供应商可以自如地进入或者退出市场 Chapter 1

  8. Perfectly Competitive Markets • Discussion Questions • What are some barriers to entry and exit? 阻碍企业自由进出市场的障碍是什么？ • Are all markets competitive? 所有的市场都是竞争性市场吗？ • When is a market highly competitive? 什么情况下市场是高度竞争的？ Chapter 1

  9. Profit Maximization • Do firms maximize profits? 利润最大化？ • Possibility of other objectives 其他目标 • Revenue maximization 收入最大化 • Dividend maximization 红利最大化 • Short-run profit maximization 短期利润最大化 Chapter 1

  10. Profit Maximization • Do firms maximize profits? • Implications of non-profit objective 非利润最大化目标的意义 • Over the long-run investors would not support the company 长期而言，投资者不会支持其行为 • Without profits, survival unlikely 没有利润，公司本身也无法生存 Chapter 1

  11. Profit Maximization • Do firms maximize profits? • Long-run profit maximization is valid and does not exclude the possibility of altruistic behavior. 长期利润最大化是合理的假说；当然不能排斥利它行为存在的可能性 Chapter 1

  12. Marginal Revenue, Marginal Cost,and Profit Maximization • Determining the profit maximizing level of output 决定利润最大化的产出水平 • Profit ( ) = Total Revenue - Total Cost 利润＝总收入－总成本 • Total Revenue (R) = Pq • Total Cost (C) = Cq • Therefore: Chapter 1

  13. Total Revenue 总收入 R(q) Slope of R(q) = MR 斜率＝边际收益 边际收益递减 Profit Maximization in the Short Run Cost, Revenue, Profit ($s per year) 0 Output (units per year) Chapter 1

  14. C(q) Total Cost 总成本 Slope of C(q) = MC 边际成本 Why is cost positive when q is zero? 短期内存在固定成本，因此产量为零，成本不为零 Profit Maximization in the Short Run Cost, Revenue, Profit $ (per year) 0 Output (units per year) Chapter 1

  15. Marginal Revenue, Marginal Cost,and Profit Maximization • Marginal revenue is the additional revenue from producing one more unit of output. 边际收益是产量增加一个单位时收入的增加量 • Marginal cost is the additional cost from producing one more unit of output. 边际成本时产量增加一个单位时成本的增加量 Chapter 1

  16. C(q) R(q) A B q0 q* Marginal Revenue, Marginal Cost,and Profit Maximization • Comparing R(q) and C(q) • Output levels: 0- q0: • C(q)> R(q) • Negative profit • FC + VC > R(q) • MR ＜MC • Indicates higher profit at higher output Cost, Revenue, Profit ($s per year) 0 Output (units per year) Chapter 1

  17. Cost, Revenue, Profit $ (per year) C(q) R(q) A B q0 q* 0 Output (units per year) Marginal Revenue, Marginal Cost,and Profit Maximization • Comparing R(q) and C(q) • Question: Why is profit negative when output is zero? 收入不足以抵消固定成本和可变成本 Chapter 1

  18. Cost, Revenue, Profit $ (per year) C(q) R(q) A B q0 q* 0 Output (units per year) Marginal Revenue, Marginal Cost,and Profit Maximization • Comparing R(q) and C(q) • Output levels: q0 - q* • R(q)> C(q) • MR > MC • Indicates higher profit at higher output • Profit is increasing Chapter 1

  19. Cost, Revenue, Profit $ (per year) C(q) R(q) A B q0 q* 0 Output (units per year) Marginal Revenue, Marginal Cost,and Profit Maximization • Comparing R(q) and C(q) • Output level: q* • R(q)= C(q) • MR = MC • Profit is maximized Chapter 1

  20. Cost, Revenue, Profit $ (per year) C(q) R(q) A B q0 q* 0 Output (units per year) Marginal Revenue, Marginal Cost,and Profit Maximization • Question • Why is profit reduced when producing more or less than q*? 此处边际收益等于边际成本，之前边际收益大于边际成本；之后边际收益小于边际成本 Chapter 1

  21. Cost, Revenue, Profit $ (per year) C(q) R(q) A B q0 q* 0 Output (units per year) Marginal Revenue, Marginal Cost,and Profit Maximization • Comparing R(q) and C(q) • Output levels beyond q*: • R(q)> C(q) • MC > MR • Profit is decreasing Chapter 1

  22. Cost, Revenue, Profit $ (per year) C(q) R(q) A B q0 q* 0 Output (units per year) Marginal Revenue, Marginal Cost,and Profit Maximization • Therefore, it can be said: • Profits are maximized when MC = MR. Chapter 1

  23. Marginal Revenue, Marginal Cost,and Profit Maximization Chapter 1

  24. Marginal Revenue, Marginal Cost,and Profit Maximization Chapter 1

  25. Marginal Revenue, Marginal Cost,and Profit Maximization • The Competitive Firm 竞争性厂商 • Price taker 价格接受者 • Market output (Q) and firm output (q) • Market demand (D) and firm demand (d) • R(q) is a straight line 收益曲线是一条直线 Chapter 1

  26. $4 d $4 D Demand and Marginal Revenue Facedby a Competitive Firm Price $ per bushel Price $ per bushel Firm 厂商 Industry 行业 Output (millions of bushels) Output (bushels) 100 200 100

  27. Marginal Revenue, Marginal Cost,and Profit Maximization • The Competitive Firm • The competitive firm’s demand 竞争性厂商的需求 • Individual producer sells all units for $4 regardless of the producer’s level of output. 个别生产者只能在固定价格销售产品，与自身的产出水平无关 • If the producer tries to raise price, sales are zero. 如果生产者试图抬高价格，则销售量为零 Chapter 1

  28. Marginal Revenue, Marginal Cost,and Profit Maximization • The Competitive Firm • The competitive firm’s demand • If the producers tries to lower price he cannot increase sales 生产者降价无助于提高销售产量 • P = MR = AR 产品价格=边际收益＝平均收益 Chapter 1

  29. Marginal Revenue, Marginal Cost,and Profit Maximization • The Competitive Firm • Profit Maximization 利润最大化的条件－所选择的产量水平需满足： • MC(q) = MR = P 边际成本＝边际收益＝产品价格 Chapter 1

  30. Choosing Output in the Short Run选择短期产出 • We will combine production and cost analysis with demand to determine output and profitability. 我们必须把生产分析与成本分析结合，以确定产出水平和利润水平 Chapter 1

  31. MC Lost profit for qq < q* Lost profit for q2 > q* A D AR=MR=P ATC C B AVC At q*: MR = MC and P > ATC q1 : MR > MC and q2: MC > MR and q0: MC = MR but MC falling q0 q1 q* q2 A Competitive Firm Making a Positive Profit 竞争性厂商的短期利润最大化 Price ($ per unit) 60 50 40 30 20 10 0 1 2 3 4 5 6 7 8 9 10 11 Output Chapter 1

  32. MC ATC B C D P = MR A At q*: MR = MC and P < ATC Losses = P- AC) x q* or ABCD AVC F E q* A Competitive Firm Incurring Losses 竞争性厂商短期内面临亏损 Price ($ per unit) Would this producer continue to produce with a loss? Output Chapter 1

  33. Choosing Output in the Short Run • Summary of Production Decisions • Profit is maximized when MC = MR 当边际成本等于边际收益（价格）时，利润最大化 • If P > ATC the firm is making profits. 当价格高于平均总成本时，厂商可以盈利 Chapter 1

  34. Choosing Output in the Short Run • If AVC < P < ATC the firm should produce at a loss. • 当价格高于平均可变成本但低于平均总成本时，厂商应该在亏损情况下继续生产 • If P < AVC < ATC the firm should shut-down. • 当价格低于平均可变成本和平均固定成本时，厂商应停止生产 Chapter 1

  35. 厂商选择的产出水平是边际收益与边际成本相等之处厂商选择的产出水平是边际收益与边际成本相等之处 前提是价格需高于平均可变成本 MC ATC P2 AVC P1 What happens if P < AVC? P = AVC q1 q2 A Competitive Firm’s Short-Run Supply Curve 竞争性厂商的短期供给曲线 Price ($ per unit) Output Chapter 1

  36. A Competitive Firm’sShort-Run Supply Curve • Observations: • P = MR • MR = MC • P = MC • Supply is the amount of output for every possible price. Therefore: • If P = P1, then q = q1 • If P = P2, then q = q2 Chapter 1

  37. A Competitive Firm’sShort-Run Supply Curve S = MC above AVC 厂商供给曲线是位于平均可变 成本最低点以上的边际成本曲线 Price ($ per unit) MC ATC P2 AVC P1 P = AVC Shut-down Output q1 q2 Chapter 1

  38. A Competitive Firm’sShort-Run Supply Curve竞争性厂商的短期供给曲线 • Observations: • Supply is upward sloping 供给曲线向右上倾斜 • Higher price compensates the firm for higher cost of additional output and increases total profit because it applies to all units. 市场价格上升，企业增加产量，提高价格使扩大生产有利可图；同样增加厂商的总利润，因为这一价格适用于厂商生产的全部产量 Chapter 1

  39. A Competitive Firm’sShort-Run Supply Curve • Firm’s Response to an Input Price Change 厂商对投入品价格变化的应对 • When the price of a firm’s product changes, the firm changes its output level, so that the marginal cost of production remains equal to the price. 当投入品价格变化，厂商会改变其产出水平直到产出的边际成本与价格相等 Chapter 1

  40. Input cost increases and MC shifts to MC2 and q falls to q2. MC2 Savings to the firm from reducing output MC1 $5 q2 q1 The Response of a Firm toa Change in Input Price Price ($ per unit) Output Chapter 1

  41. The MC of producing a mix of petroleum products from crude oil increases sharply at several levels of output as the refinery shifts from one processing unit to another. SMC How much would be produced if P = $23? P = $24-$25? The Short-Run Productionof Petroleum Products Cost ($ per barrel) 27 26 25 24 Output (barrels/day) 23 8,000 9,000 10,000 11,000 Chapter 1

  42. The Short-Run Productionof Petroleum Products • Stepped SMC indicates a different production (cost) process at various capacity levels. 逐步上升的短期边际成本曲线说明在不同的产量阶段，成本构成不同 • Observation: • With a stepped MC function, small changes in price may not trigger a change in output. 对于阶段性上升的边际成本，价格的小幅度变化不一定会引发产出的变化 Chapter 1

  43. The Short-Run Market Supply Curve短期市场供给曲线 • The short-runmarket supply curve shows the amount of output that the industry will produce in the short-run for every possible price. 短期市场供给曲线表示在每一可能的价格下行业在短期中生产的产量 • Consider, for simplicity, a competitive market with three firms: Chapter 1

  44. S The short-run industry supply curve is the horizontal summation of the supply curves of the firms. MC1 MC2 MC3 P3 P2 P1 Industry Supply in the Short Run $ per unit Question: If increasing output raises input costs, what impact would it have on market supply? Quantity 0 2 4 5 7 8 10 15 21 Chapter 1

  45. The Short-Run Market Supply Curve • Elasticity of Market Supply Chapter 1

  46. The Short-Run Market Supply Curve • Perfectly inelastic short-run supply arises when the industry’s plant and equipment are so fully utilized that new plants must be built to achieve greater output. • 供给完全无弹性： 行业的厂房设备完全被利用；必须建立新厂房提高产量（耗时较长） • Perfectly elastic short-run supply arises when marginal costs are constant. • 供给完全弹性：边际成本为常数 Chapter 1

  47. The Short-Run Market Supply Curve • Producer Surplus in the Short Run 短期生产者剩余 • Firms earn a surplus on all but the last unit of output. 厂商能够获得除最后一单位外所有产量对应的剩余 • The producer surplus is the sum over all units produced of the difference between the market price of the good and the marginal cost of production. 生产者剩余是所有生产单位边际生产成本和商品市场价格之间差额的总和 Chapter 1

  48. At q* MC = MR. Between 0 and q , MR > MC for all units. Producer Surplus MC AVC B A P Alternatively, VC is the sum of MC or ODCq* . R is P x q*or OABq*. Producer surplus = R - VC or ABCD. D C q* Producer Surplus for a Firm Price ($ per unit of output) 0 Output Chapter 1

  49. The Short-Run Market Supply Curve • Producer Surplus in the Short-Run 生产者剩余＝PS＝R－VC Chapter 1

  50. The Short-Run Market Supply Curve • Observation • Short-run with positive fixed cost 短期内固定成本为正时 Chapter 1

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