Chap7消费者、生产者与市场效率.ppt

消费者、生产者与市场效率 Consumers, Producers, and the Efficiency of Markets 第七章 Chapter 7 在本章中，我们要讨论福利经济学（welfare economics）这个主题，即研究资源配置如何影 响经济福利。我们从考察买者和卖者从参与市 场中得到的利益开始，然后考虑社会如何可以 使这种利益尽量达到最大。 在前面几章中，我们说明了在市场经济中 供给和需求的力量如何决定了物品的价格和销 售量。那么，这种价格和销售对买者和卖者来 说是不是最满意的？对我们整个社会来说是否 是最佳的？ 再看市场均衡 Revisiting the Market Equilibrium 市场均衡价格和数量使买者和卖者的总福利最大化吗 Do the equilibrium price and quantity maximize the total welfare of buyers and sellers? u市场均衡反映出市场配置稀缺资源的方式。 Market equilibrium reflects the way markets allocate scarce resources. u市场的资源配置是否令人满意，取决于福利经济学 Whether the market allocation is desirable is determined by welfare economics. 福利经济学 Welfare Economics 福利经济学研究资源配置如何影响经济福利。 Welfare economics is the study of how the allocation of resources affects economic well-being. u买者和卖者从参与市场中收益。 Buyers and sellers receive benefits from taking part in the market. u市场上供求均衡可以使买者和卖者的总福利 最大化。 The equilibrium in a market maximizes the total welfare of buyers and sellers. 福利经济学 Welfare Economics 市场均衡导致收益最大化，因此导致消费 者和生产者的总体福利的最大化。 Equilibrium in the market results in maximum benefits, and therefore maximum total welfare for both the consumers and the producers of the product. Welfare Economics u消费者剩余衡量买方的经济福利。 Consumer surplus measures economic welfare from the buyers side. u生产者剩余衡量卖方的经济福利。 Producer surplus measures economic welfare from the sellers side. 消费者剩余 Consumer Surplus n支付意愿是买者愿意且能够为某一物品支付的 最高价格。 Willingness to pay is the maximum price that a buyer is willing and able to pay for a good. u它衡量买者对物品或服务的评价是多少 It measures how much the buyer values the good or service. 消费者剩余 Consumer Surplus 消费者剩余是买者的支付意愿减买者 的实际支付额。 Consumer surplus is the amount a buyer is willing to pay for a good minus the mount the buyer actually pays for it. 让我们来参加一场拍卖会 n拍卖品：外星人的经原课本1本 n拍卖的参加者：John, Paul, George and Ringo. n拍卖规则：买者由低到高出价，每次加价以10美 元为最小单位。出价最高者得到这个课本，并支 付其报价。 谁得到课本，成交价是多少？ 四个可能买者的支付意愿 Four Possible Buyers Willingness to Pay. 让我们来参加一场拍卖会 nJohn 将得到课本，成交价为80（或90）美元。 nJohn 得到的消费者剩余（也是市场的总消费者剩 余）为： 100-80=20 美元 n假设有两本课本呢？ John和Paul 将得到课本，成交价为70美元。 John得到100-70=30 美元的消费者剩余；Paul得到80 -70=10 美元的消费者剩余。 市场的总消费者剩余为30+10=40 美元。 消费者剩余 Consumer Surplus n消费者剩余与一种物品的需求曲线密切相关。 Consumer surplus is closely related to the demand curve for a product. n市场需求曲线画出了在不同的价格下，买者愿 意和能够购买的数量。 The market demand curve depicts the various quantities that buyers would be willing and able to purchase at different prices. 四个可能买者的支付意愿 Four Possible Buyers Willingness to Pay. 用需求曲线衡量消费者剩余 Measuring Consumer Surplus with the Demand Curve. P 50 70 80 0 $100 1234 Q 约翰的支付意愿 保罗的支付意愿 乔治的支付意愿 林格的支付意愿 D 用需求曲线衡量消费者剩余 Measuring Consumer Surplus with the Demand Curve. n在任何一种数量下，需求曲线给出的价格（需求曲 线的高度）表示边际买者的支付意愿；边际买者是 如果价格再高一点，就首先离开的买者。 At any quantity, the price given by the demand curve shows the willingness to pay of the marginal buyer, the buyer who would leave the market first if the price were any higher. n由于需求曲线反应了买者的支付意愿，我们可以用 它衡量消费者剩余。 Because the demand curve reflects buyers Willingness to pay, we can also use it to measure consumer surplus. Price of Album 50 70 80 0 $100 1234 Quantity of Albums Demand 约翰的消费者剩余 ($20) Price = $80 用需求曲线衡量消费者剩余 Measuring Consumer Surplus with the Demand Curve. Price of Album 50 70 80 0 $100 1234 Quantity of Albums Demand 约翰的消费者剩余($30) 总消费者剩余 ($40) Price = $70 保罗的消费者剩余($10) 用需求曲线衡量消费者剩余 Measuring Consumer Surplus with the Demand Curve. 用需求曲线衡量消费者剩余 Measuring Consumer Surplus with the Demand Curve 需求曲线以下和价格以上的面积衡量市 场的消费者剩余。 The area below the demand curve and above the price measures the consumer surplus in the market. Q2 P2 Quantity Price 0 Demand 原来的 消费者剩余 原来的消费 者增加的消 费者剩余 新消费者的 消费者剩余 Q1 P1 DE F B C A 价格如何影响消费者剩余 How the Price Affects Consumer Surplus 消费者剩余与经济福利 Consumer Surplus and Economic Well-Being 消费者剩余，即买者愿意为一种物品支付的金 额减他们实际支付的金额，衡量了消费者从一种 物品中得到的买者自己感觉到的收益。 Consumer surplus, the amount that buyers are willing to pay for a good minus the amount they actually pay for it, measures the benefit that buyers receive from a good as the buyers themselves perceive it. 生产者剩余 Producer Surplus u生产者剩余：卖者出售一种物品得到 的金额减去卖者的成本。 Producer surplus is the amount a seller is paid minus the cost of production. u它衡量了卖者参与市场得到的收益。 It measures the benefit to sellers participating in a market. 四个可能卖者的成本 The Costs of Four Possible Sellers. 生产者剩余与供给曲线 Producer Surplus and the Supply Curve n正如消费者剩余与需求曲线密切相关，生产者剩 余也与供给曲线密切相关。 Just as consumer surplus is related to the demand curve, producer surplus is closely related to the supply curve. n在任何一种数量上，供给曲线给出的价格表示边 际卖者的成本，这个边际卖者是如果价格再略低 一点就首先离开市场的卖者。 At any quantity, the price given by the supply curve shows the cost of the marginal seller, the seller who would leave the market first if the price were any lower. 四个卖者的供给量 Supply Schedule for the Four Possible Sellers 生产者剩余和供给曲线 Producer Surplus and the Supply Curve. Quantity of Houses Painted Price of House Painting 500 800 $900 0 600 1234 格拉玛的成本 乔治亚的成本 弗瑞达的成本 玛丽的成本 Supply 供给曲线以上和价格以下的面积衡量市 场的生产者剩余。 The area below the price and above the supply curve measures the producer surplus in a market. 生产者剩余与供给曲线 Producer Surplus and the Supply Curve 用供给曲线衡量生产者剩余 Measuring Producer Surplus with the Supply Curve. Quantity of Houses Painted Price of House Painting 500 800 $900 0 600 1234 Supply 格拉玛的生产者剩余($100) Price = $600 用供给曲线衡量生产者剩余 Measuring Producer Surplus with the Supply Curve. Quantity of Houses Painted Price of House Painting 500 800 $900 0 600 1234 Supply 格拉玛的生产者剩余($300) Price = $800 乔治亚的生产者剩余($200) 总生产者剩余 ($500) P2 Q2Quantity Price 0 Supply Q1 P1 A B C 原先的生 产者剩余 原来生产者的额 外生产者剩余 D E F 新生产者的 生产者剩余 价格如何影响生产者剩余 How Price Affects Producer Surplus. 市场均衡的评价 Evaluating the Market Equilibrium Price 均衡价格 Equilibrium price 0Quantity均衡数量 Equilibrium quantity A Supply C B Demand D E 市场均衡时的消费者与生产者剩余 Consumer and Producer Surplus in the Market Equilibrium Price 均衡价格 0Quantity均衡数量 A Supply C B Demand D E 生产者剩余 消费者剩余 市场效率 Market Efficiency 消费者剩余和生产者剩余可以用来回答下列 问题：由自由市场决定的资源配置从某种意 义上来说是令人满意的配置吗？ Consumer surplus and producer surplus may be used to address the following question: Is the allocation of resources determined by free markets in any way desirable? 经济福利与总剩余 Economic Well-Being and Total Surplus and 消费者剩余 Consumer Surplus = 买者评价 Value to buyers _ 买者支付的金 额 Amount paid by uyers 生产者剩余 Producer Surplus = 卖者得到的金额 Amount received by sellers _ 卖者的 成本 Cost to sellers 经济福利与总剩余 Economic Well-Being and Total Surplus or 总剩余 Total Surplus = 买者的评 价 Value to buyers _ 卖者的成 本 Cost to sellers 总剩余 Total Surplus = 消费者剩余 Consumer Surplus 生产者剩余 Producer Surplus + 效率 Efficiency 当资源配置使总剩余最大化时，我们说，这 种配置达到效率。 Efficiency is achieved when the allocation of resources maximizes total surplus. 如果你是一个仁慈的社会计划者， 你将进行怎样的配置以达到效率？ 效率 Efficiency n条件1：在给定的数量下，一种物品的分 配使得它： 由最低成本的那些卖者来生产； 由最高评价（支付意愿）的那些买者来消费 n条件2：给定上述的分配方案，该物品的 数量是使得总剩余最大的数量。 有效率的配置 Efficient Allocation 评价/成本 0 Quantity有效率数量 卖者成本曲线 买者评价曲线 卖者的 成本 买者的 评价 买者的 评价 卖者 的成本 买者的评价大于卖者的成本 买者的评价小于卖者的成本 有效率的配置 Efficient Allocation 市场均衡是有效率的 Market Equilibrium is Efficient 关于市场运行结果的三大结论 Three Insights Concerning Market Outcomes n自由市场把物品的供给分配给对这些物品评价最高的 买者。 Free markets allocate the supply of goods to the buyers who value them most highly. n自由市场把物品的需求分配给可以以最低成本生产这 些物品的卖者。 Free markets allocate the demand for goods to the sellers who can produce them at least cost. n自由市场的总生产量使消费者和生产者剩余最大化 Free markets produce the quantity of goods that maximizes the sum of consumer and producer surplus. u这三个关于市场结果的观点告诉我们，供求均衡 使消费者与生产者剩余之和最大化。换句话说，均 衡结果是资源的有效配置。 u现在我们可以更好地评价我们在第1章中讨论的 亚当斯密的市场这只看不见的手。看不见的手指 导了使买者与卖者总剩余最大化的经济资源配置。 这个结论解释了经济学家通常支持自由市场是组织 经济活动的最好方法的原因。 无效率与贸易 Inefficiency and Trade n如果一种配置是无效率的，那么，买者或卖 者内部、买者和卖者之间的贸易好处就还没 有完全实现。 If an allocation is not efficient, then some of the gains from trade among buyers and sellers are not being realized. n市场配置是有效率的，因为它实现了所有的 贸易好处。 市场的有效率性 The Efficiency of the Market n因为市场均衡时的资源配置是有效率的，社会计划 者可以让市场自己找出结果。 Because the equilibrium outcome is an efficient allocation of resources, the social planner can leave the market outcome as he/she finds it. n这种完全放开的政策可以用法语自由放任来表述。 This policy of leaving well enough alone goes by the French expression laissez faire. n亚当.斯密：市场是只看不见的手 n原理之六：市场通常是组织经济活动的好方式 效率与平等 Efficiency and Equity 除了效率之外，社会计划者也会关心 平等在不同的买者和卖者之间福利分 配的公平性。 In addition to market efficiency, a social planner might also care about equity the fairness of the distribution of well- being among the various buyers and sellers. 例子：倒卖门票 Example: Ticket Scalping n如果一个经济能有效地配置其稀缺资源，物品必 须给与对此评价最高的那些消费者。倒卖门票是 市场如何实现有效结果的一个例子 If an economy is to allocate its scarce resources efficiently, goods must get to those consumers who value them most highly. Ticket scalping is one example of how markets reach efficient outcomes. 例子：倒卖门票 Example: Ticket Scalping n倒票者购买戏剧、音乐会和运动会的门票，并以 高出他们原来成本的价格卖出这些票。通过收取 市场可以承受的最高价格，倒票者有助于保证对 门票支付意愿最高的人实际上得到这些票。 Scalpers buy tickets to plays, concerts, and sports events and then sell the tickets at a price above their original cost. By charging the highest price the market will bear, scalpers help ensure that consumers with the greatest willingness to pay for the tickets actually do get them. 警告：假设的作用 Warning: Assumptions n为了得出市场有效率的结论，我们作出了一些关 于市场如何运行的假设。 n当这些假设不成立的时候，关于市场均衡有效率 的结论可能就不成立了。 n两个重要的假设 市场是完全竞争的，即不存在市场势力。(Market power) 市场结果只与买者和卖者相关，即无外部性 (externalities) 。 n市场失灵(market failures) ：自由的市场不能有 效率地配置资源。 为什么关于市场有效率的模型 如此重要，尽管假设与现实会有距离 n当这些假设成立的时候，关于市场均衡有 效率的结论成立 n即使在现实中这些假设不完全成立，它仍 然为我们分析问题提供了一个基准或标尺 (benchmark)或称参照系(reference) n有了这一基准或标尺，我们对现实的进一 步分析就有力量。 n比如对市场势力和外部性情况的分析。 市场势力 Market Power n如果市场不完全竞争，市场势力便形成。 If a market system is not perfectly competitive, market power may result. n市场势力是影响价格的能力。 Market power is the ability to influence prices. n市场势力可以使市场无效率，因为它会使价格和 数量偏离供求均衡点。 Market power can cause markets to be inefficient because it keeps price and quantity from the equilibrium of supply and demand. 外部性 Externalities n当市场的结果影响了买者和卖者以外的人时，产生外部性 Externalities are created when a market outcome affects individuals other than buyers and sellers in that market. n外部性使市场福利还要取决于买者评价和卖者评价之外的 其他因素。 Externalities cause welfare in a market to depend on more than just the value to the buyers and cost to the sellers. n当买者和卖者在决定消费和生产时不考虑外部性的时候， 市场均衡可能是无效率的。 When buyers and sellers do not take externalities into account when deciding how much to consume and produce the equilibrium in the market can be inefficient. 总结 Summary n消费者剩余衡量买者参与市场的收益。 Consume