萨缪尔森《微观经济学》(第18版)笔记和课后习题详解(不确定性和博弈论)【圣才出品】
萨缪尔森经济学Economics第十八版 18th 课后概念、习题答案2
C H A P T E R 2 T h e S h i f t i n g B o u n d a r y B e t w e e nM a r k e t sa n d G o v e r n m e n tCHAPTER OVERVIEW AND TEACHING TIPSThis chapter introduces a series of fundamental ideas and concepts that define the essence of the economic problem. They are important because they form the foundation for the analysis of a market economy. The tools and methods that you present to students in this chapter will be carried throughout the text and developed in greater detail as you make your way through the course. Here is a great opportunity for you to give students a broad introduction to “the economic way of thinking.”The chapter begins with an introduction to markets. Because this text is grounded in market analysis, take the time to illustrate the basics concepts of upward-sloping supply, downward-sloping demand, and equilibrium. Later chapters will fill in important details.Section B broadens the students’ view of the economy from a partial equilibrium setting to a more general equilibri- um setting. This allows you to develop the important interactions between agents and markets. Roles for money and capital are established as well as the importance of property rights. All of these components of a market economy are important to its proper functioning.Section C introduces a role for government in an economy. Efficiency and equity are examined as well as macroe- conomic goals like growth and stability.LEARNING OBJECTIVES1. Describe what is meant by the term market and describe the process of achieving equilibrium in a market economy.2. Use your definition of market equilibrium to address three basic economic problems that confront all societies.3. Explain how the price system works as an invisible hand, allocating goods and services in a market economy.4. Understand the importance of specialization, the division of labor, money, factors of production and capital andproperty rights in the functioning of a modern economy.5. Use a circular-flow diagram to illustrate the relationships between agents and markets in a modern economy.6. Make a case for government intervention in a mixed market economy in order to promote efficiency, equity, andmacroeconomic growth and stability.SUGGESTED ANSWERS TO QUESTIONS IN THE TEXT1. In all of these cases, a combination of consumer choice and government directives or incentive plans determine theultimate allocation of resources.2. Auctions are not always practical, ration coupons hold prices artificially low, and first come first served leads tohigh opportunity costs of standing in line. A market “rations” goods to those consumers who can a fford them.3. There are lots of potential government failures. Some would argue that AFDC has been a failure; more children livein poverty in the United States today than in many other industralized countries. Would it be better to live with this market failure? We shall see.4. Pollution limitations: improving efficiency (public bad)Income supplements: equity (redistribution program)Phone regulation: efficiency (prices higher, output lower with monopoly)56 C HAPTER 2: T HE S HIFTING B OUNDARY B ETWEEN M ARKETS AND G OVERNMENT 5. Money goes in the opposite direction, i.e., from businesses to the suppliers of inputs and from households to thesuppliers of outputs. Money functions to make transactions easier and more efficient.6. Division and specialization of labor is obvious in a college or university. Faculty membersteach classes, staff members clean classrooms and deliver mail, and administrators manage budgets and raise funds for the institution. Overspecialization might leave some individuals unemployable if the demand for their type of labor decreases.7. There were arguments that slaves were property. Some argued that because slaves had to be housed and fed frombirth and trained from adolescence, they represented “human” capital—human elements of roundabout production.I am sure that you can find a lot to write about such a dehumanizing thought.8. Social security helps to promote equity in the distribution of income. National defense represents provision ofa public good. Unemployment insurance provides for stability through the business cycle. Interest on the publicdebt might promote stability by allowing government to use fiscal policy more effectively.Administration of justice often deals with imperfect competition and market failure. Pollution control battles a negative externality, while funding for basic science encourages a positive externality.9. Unlike a private good where you must reveal your preferences to receive the good, public goods are provided by thegovernment and are paid for by taxes collected by the government. It is important that the one who is paying for the good have a say in what is provided by the government.a. The best way to voice your concern about defense spending is at the ballot box.b. You can voice your displeasure at the ballot box or move to a jurisdiction where the tax is not being collected.c. Take alternative means of travel to Miami or not travel to Miami.DISCUSSION QUESTIONS1. What is meant by a “mixed economy?” Is it socialist? Communist?2. It has been said that prices serve a rationing function and a guidepost function. What could this mean?3. Use a market diagram to show how prices coordinate the behavior of buyers and sellers. What if buyers wantto purchase more units of a particular good than sellers want to provide? How will the price system provideincentivesin this situation?4. The how, what, and for whom questions are solved differently in different economic systems. Consider each ofthe following and explain how the three big questions of economic organization are solved (a) within your family,(b) within your college or university, and (c) in the agriculture industry.5. What considerations do you think have caused leaders in Eastern Europe to lessen their hostility toward the valueof the pricing system? What about the people? If market economies work better than other types of economic rationing systems, why is it so difficult for countries like Russia and Poland to chart a new economic course?6. Why do you suppose that history has never seen a period of complete laissez-faire? Do youthink nineteenth century America came reasonably close? What would your Utopia look like?7. “Losses are as important as profits in a pricing system.” Why? What function do losses serve?8. Identify a few economic areas in which the government is currently active. Are these activities directedprimarily toward correcting problems of equity, efficiency, or stability? Are they working? Discuss positive and negative effects of government intervention in the economy.9. The social security system was devised to help Americans during their retirement years. It has grown beyondthat objective. What are the current objectives of the system, and are there side effects that add to or subtract from its ability to meet those objectives?10. Why is the decision whether to consume today or tomorrow so important to society? Who makes this decision inthe United States? In Cuba?11. “A socialist nation and a capitalist nation do not differ in the fundamental economic problems that they face;they differ in the ways they go about solving those problems.” Do you agree? Why or why not? Do they also differ in what they consider to be desirable solutions?12. Do you think society could organize 200 million people on the principles of the kibbutz or cooperative? Why orwhy not?13. “Th e need of U.S. manufacturers to spend large sums on advertising to stimulate artificial wantsindicates that economic scarcity will soon lose its relevance.” Is this true, and if not true no w, is it likely to become so?14. Who loses, or stands to lose, when trade opens? Do they always lose? Can short-term losses turn into long-term gains?C HAPTER 2: T HE S HIFTING B OUNDARY B ETWEEN M ARKETS AND G OVERNMENT 715. What types of stabilization policies can you think of? Are they consistent with the objectives of equity andefficiency?16. Equity and efficiency can run counter to each other. Why?17. Do markets always do a good job of distributing resources to people who need them most? To people who wantthem most? Explain.ESSAY QUESTIONS1. Sketch a diagram to show how markets and prices link households and businesses to solve the three economic prob-lems. Explain the direction of money flows and the accompanying flows of goods and factor inputs.2. Prices in a market system have sometimes been described as fulfilling a “rationing” function.a. In what sense do prices “ration?” Why is rationing needed in an economic system as productive as ours?b. In the market for energy, what are the factors determining to whom the world’s supply of oil is distributed?c. Suppose a shortage of wheat exists. How does the price system react to bring about anincrease in wheat production?3. Indicate the manner in which the market system provides a solution to the for whom question in a free enterpriseeconomy. In the present American economy, what other factors are important?4. “The U.S. economic system is mixed in at least two senses.” Elaborate on this statement.5. List and discuss (a) the various factors inherent in our economy that make perfect competitionan unrealistic description of our economic system; (b) the factors responsible for the existence of monopoly elements in our society.6. “The bulk of all economic activity is directed toward the future.” What would be the significance of this for oursociety? Is it true?7. Government in a mixed society can (a) purchase goods and services, (b) produce goods and services, (c) transferincome from one group of people to another, (d) tax its citizens, and (e) borrow and/or lend money. Pick examples of each and discuss how equity, efficiency, and stabilization objectives are met in your examples.8. In The Zero Sum Society, Lester Thurow speculates on how economic interaction can take placewithout one person’s gain resulting in another’s loss. What do you think of that notion? How might it relate to globalization?9. Contrast the use of barter and money in a modern mixed economy that uses many capital goods and involves muchspecialization and interdependence. Concentrate on the efficiency of transactions—the cost involved in conducting business.10. “Specialization gives rise to di fferences in skill; differences in skill give rise to s pecialization.” Can both statementsbe true? Would specialization be worthwhile if everyone were identical?11. In what sense do specialization and division of labor depend on the size of the market? Does this help explainthe phenomenon of continuing economic growth?12. Specialization is not entirely problem-free. Discuss some of the troublesome effects of specialization on workers,the workplace, and society as a whole.13. Country A can produce all goods more efficiently than Country B. The opportunity costs of production, however,are different. Can trade ever benefit Country A?14. Discuss the fundamental difference between Milton Friedman’s ideas about a market economy and John MaynardKeynes’ ideas about a market economy. What are their major points of disagreement?15. Discuss the problems associated with providing the service of a lighthouse to ships.。
萨缪尔森《微观经济学》(第18版)笔记和课后习题详解(供给和需求的应用)【圣才出品】
第4章 供给和需求的应用4.1 复习笔记一、需求弹性和供给弹性1．需求的价格弹性（1）含义需求价格弹性是指需求量相对于价格变化作出的反应程度，即某商品价格下降或上升百分之一时所引起的对该商品需求量增加或减少的百分比。
（2）公式①需求弧弹性表示需求曲线上两点之间的弹性，其计算公式为：。
D D D Q P E P Q ∆=⋅∆②点弹性表示的是需求曲线上某一点的弹性，其计算公式为：。
d d D D DQ P E P Q =⋅③计算需求的弧弹性时，两点之间的变动率既可以以起点为基础，也可以以终点为基础，还可以以中点为基础。
也就是，弧弹性公式中（，）取起点、终点与中点的坐标P D Q 都成立。
一般地，以中点为基准计算弧弹性，其公式为：()()1212/2/2D Q PE Q Q P P ∆∆=÷++（3）类型①，称为完全无弹性，表明需求量为一常量，即需求量不随价格变化而变化，0D E =需求曲线和纵轴平行，其斜率为无穷大。
这是一种特例，如火葬费、自来水费等近似于无弹性，如图4-1所示。
图4-1 完全无弹性与完全弹性②，称为无穷大弹性或完全弹性，表明价格为一定的情况下，需求量无限大，D E =∞此时，需求曲线斜率为零。
这也是一种特例，如战争时期的常规军用物资及完全竞争条件下的商品可视为需求弹性无限大，如图4-1所示。
③，称为富有弹性，表明需求量的变动率快于价格的变动率，即需求量对价1D E <<∞格变化反应强烈，此时，需求曲线斜率为负。
这类商品称之为奢侈品，一般指高档消费品，如图4-2（a ）所示。
④，称为单一弹性或单位弹性，表明需求量的变动率等于价格的变动率，即需1D E =求和价格以相同幅度变动，这是一种特例，如图4-2（b ）所示。
⑤，称为缺乏弹性，表明需求量的变动率小于价格的变动率，即需求量变化01D E <<对价格变化反应缓和。
此时，需求曲线斜率为负。
这类商品为生活必需品，如图4-2（c ）所示。
萨缪尔森《微观经济学》(第18版)笔记和课后习题详解(需求和消费者行为)【圣才出品】
第5章需求和消费者行为5.1 复习笔记一、选择和效用理论1．消费者的选择在解释消费行为的过程中，经济学依赖于一个基本的前提假定，即人们倾向于选择他们认为最具价值的那些物品和服务。
也就是说，消费者运用有限的货币收入，通过有选择的购买行为以取得最大的效用。
消费者的选择由两个因素决定：（1）消费者的偏好；（2）消费者的收入水平和所购买商品或劳务的价格水平。
2．效用（1）效用的概念效用是消费者从消费某种物品或劳务中所得到的满足程度，是消费者的一种心理感受而不是物品的客观用途。
同一商品效用的大小因人、因时、因地而不同。
对效用的不同度量形成了两种效用理论，即基数效用论与序数效用论。
（2）基数效用论基数效用论产生于19世纪70年代，它认为效用的大小可以计量并且不同消费者的效用可以进行加总计算，因此可以用基数1、2、3等来表示效用，其计数单位就是效用单位。
基数效用论采用边际分析法分析消费者的均衡问题。
（3）序数效用论序数效用论产生于19世纪末、20世纪初，是对基数效用论的补充和完善，它认为效用作为一种心理现象无法计量，也不能加总求和，只能表示出满足程度的高低与顺序，因此，效用只能用序数（第一、第二、第三……）来表示。
序数效用论采用无差异曲线分析法分析消费者的均衡问题。
二、边际效用分析1．边际效用与总效用（1）边际效用的定义边际效用是消费者在一定时间内增加一单位商品的消费所得到的效用量的增量，其表达式为：()TU Q MU Q∆=∆其中，为消费者对商品的消费数量，为总效用函数。
当商品的增加量趋Q ()TU f Q =于无穷小，即时，边际效用也可以表示为：0Q ∆→()()d lim d Q TU Q TU Q MU Q Q ∆→∆==∆（2）边际效用与总效用的关系总效用是消费者在一定时期，从一定数量的商品和劳务的消费中所得到的总的满足。
边际效用是指每增加（减少）一个单位商品或劳务的消费量所引起的总效用的增（减）量。
萨缪尔森经济学Economics第十八版 18th 课后概念、习题答案5
C H A P T E R 5A P P E N D I XG e o m e t r i c a l A n a l y s i so f C o n s u m e r E q u i l i b r i u mAPPENDIX OVERVIEW AND TEACHING TIPSThis appendix is designed to explain how consumers can use their fixed incomes to create the most utility possible, given their own personal tastes and prices dictated by the market. It begins with the same styliz ed description of the consumer’s dilemma that your students have seen in the chapter, and it reaches the same results. In fact, only the method of description is different; the problem of maximizing satisfaction subject to a budget constraint is illustrated using a diagram.If your students are like mine, they will ask, “So, why bother?” To be sure, the graph will deal with the very simple case in which only two goods are involved. Y ou will need to argue that the model helps to describe consumer behavior in a simple case, and it can be used to untangle more difficult questions. The simple geometry will clarify the general nature of making choices over many goods in the face of scarcity. The content of the analysis is not confi ned to the two- good case that can be drawn on a piece of graph paper.It is important to impress upon your students that the geometric approach frees us from having to make the assump- tion that consumers’utility functions are cardinal. The geometry assumes, instead, that people can display their prefer- ences simply by ranking different possible combinations of goods. Constructing the geometry of consumer decision making requires only that consumers are able to express a preference between two or more alternatives; i.e., they are able to say which combination of goods they want. Students generally find this ordinal notion far easier to swallow thana theory that suggests that consumers are able to quantitatively evaluate consumption bundles.LEARNING OBJECTIVES1. Define an indifference curve and an indifference map.2. Explain why indifference curves may vary from one individual to the next.3. Show how it would be impossible for an indifference curve representing normal preferences to run in the southwest-to-northeast direction.4. Describe what is meant by a budget constraint.5. Explain how the budget constraint shifts when income changes or when one of the two prices changes. SUGGESTED ANSWERS TO QUESTIONS IN THE TEXT1. Indifference curves for complementary goods should be L-shaped. Indifference curves between perfect substitutesshould be downward-sloping and linear, with slope = -1.2. See diagram (top of page 24).DISCUSSION QUESTIONS1. Using an indifference map and a budget line, derive the law of downward-sloping demand.2. What is an indifference curve? Why is it convex to the origin? What is the significance of its slope at any point?2324 C HAPTER 5 A PPENDIX: G EOMETRICAL A NALYSIS OF C ONSUMER E Q UILIBRIUMFig ure5-1Will two indifference curves intersect? Why or why not?3. Using a set of indifference curves between food and clothing and a budget line, show the consumer’s new equilibri-um relative to her old equilibrium position when (a) her income increases, but both prices remain constant; (b) the price of food falls, but her income and other prices are fixed.4. The theory of consumer behavior may be applied to the choice between labor and leisure as wellas the choice among physical commodities. Each individual may choose between daily income and leisure (equal to 24 hours less the hours slept per day). Both income and leisure are positively valued. Derive the supply curve of labor forthe individual, using the indifference-curve analysis.ESSAY QUESTIONS1. Draw a budget constraint for an individual who has $400 to spend on sweaters and sweatshirts, when the price of asweater is $50 and the price of a sweatshirt is $30. If sweaters and sweatshirts are perfect substitutes, how does the consumer choose which to buy? Explain your diagram.2. Suppose the consumer in question 1 experiences a $100 decrease in her budget. How will this affect the budgetconstraint? Show in your diagram and explain.3. Suppose the consumer in question 1 notices that the price of a sweatshirt has increased to $50. How will this affectthe budget constraint? Show in your diagram and explain.4. Why do you need both an indifference map and a budget constraint to solve the consumer problem? What informa-tion do you get from the budget constraint that you do not have in the indifference map?5. Suppose you have an individual who loves jelly but who hates peanut butter. In fact, this consumer is allergic topeanut butter. Draw some indifference curves that represent these preferences over peanut butter and jelly.6. Suppose you have an individual who believes that Coke and Pepsi are perfect substitutes. That is, theconsumer gets exactly the same utility from consuming a can of Coke or a can of Pepsi. Draw some indifference curves that represent these preferences.7. Use an indifference map and a budget constraint to show why the tangency solution is preferred to any other pointon the budget constraint or under the budget constraint.。
萨缪尔森《微观经济学》(第18版)笔记和课后习题详解(含考研真题)(10-14章)【圣才出品】
第10章寡头和垄断竞争10.1复习笔记一、不完全竞争者的行为1．市场力量及其衡量市场力量表示单个企业或少数企业控制某一产业的价格和生产决策的程度。
市场力量最常用的衡量指标是一个产业的集中率。
其中，四企业集中率是指四家最大的厂商在某个产业的总产量（或发货量）中所占的百分比；同样，八企业集中率就是前八大厂商在某个产业总产量中所占的百分比。
在完全垄断的情况下，四家或八家企业的集中率都是100%，因为一家企业就生产了所有的产品，而对于完全竞争来说，这两种集中率都接近于零，因为即使是最大企业也只是行业中全部产出的一小部分。
许多经济学家认为，传统的集中率没有能够充分地衡量市场力量。
赫芬达尔—赫希曼指数（HHI）是一种更好的衡量那些占统治地位的企业在行业中的角色的方法。
该指数是将一个市场中所有参与者所占的市场份额的比率的平方进行加总而获得的。
完全竞争的HHI 接近零，而完全垄断的HHI则是10000。
2．不完全竞争的实质经济学家发现不完全竞争市场存在着三个主要的因素：成本、进入壁垒和企业策略互动。
首先，对一个企业来说，当最低平均成本所对应的产出水平占该产业总产量的相当大的比例时，只有少数几个企业可以获利并生存下来，结果就很可能形成寡头。
其次，当由于存在规模经济或政府限制而形成进入壁垒时，一个产业的竞争者的数量就会十分有限。
再次，当在某一市场上仅仅有少数几个企业时，它们必然会认识到它们之间的相互依赖性。
策略互动是寡头市场的一个新的特征，属博弈论研究领域。
当每个企业的经营战略取决于它的竞争对手的行为时，就会出现策略互动。
3．勾结寡头（1）勾结的含义一个市场不完全竞争的程度并不仅取决于企业的数量和规模，也取决于企业的行为。
当市场上企业为数不多时，它们就会注意竞争对手的行为和反应：它们可以在合作与不合作的行为之间做出选择。
当企业按照自己的计划行动，而没有公开地或暗中勾结其他企业时，它们就是以非合作方式共处，这会形成价格大战。
萨缪尔森《微观经济学》(第18版)笔记和课后习题详解(促进市场更富效率)【圣才出品】
第17章促进市场更富效率17.1 复习笔记一、企业管制：理论与实践1．管制及其种类管制的基本内容是制定政府条例和设计市场激励机制，以控制厂商的价格、销售或生产等决策。
管制传统上可分为经济管制和社会管制两类。
经济管制是指对价格、市场进入和退出条件、服务标准等所进行的控制。
这种管制在自然垄断行业中很重要。
常见的例子包括公用设施管制（电话、电、天然气、水）以及其他的产业管制（运输、电台、电视台）。
社会管制是指用来保护环境以及劳工和消费者的健康和安全的管制。
社会管制的有关规定可用以矫正经济活动所引起的各种派生后果和外部性问题。
突出的例子有：净化空气、净化水源、确保核安全、解决臭氧层变薄和气候变化等全球环境问题。
2．管制的原因管制是对企业无节制的市场力量的一种限制。
政府管制具有三大公众利益理由：一是管制企业行为可以防止垄断或寡头垄断滥用市场力量；二是管制可以矫正信息的不完全；三是管制可以纠正诸如污染之类的负的外部性问题。
（1）抑制市场力量政府应该对企业数目太少的产业实行管制，削弱过强的市场力量，以激发强有力的竞争。
政府特别应该对自然垄断这种极端情况实施管制。
当一个产业的规模经济或范围经济如此之强有力，以至于只有一个厂商能较好地生存下去时，就会产生自然垄断。
自然垄断的一个重要例子是地方水资源分配。
取水、建立水资源分配系统、铺设管道向用户送水的成本是如此之高，以至于让多个企业建立各自的供水系统势必得不偿失，这就是自然垄断。
另一种自然垄断产生于那些具有范围经济的产业，即把大量不同的产品放在一起生产，比单独生产某一种势必要来得更有效率。
一个重要且有争议的例子是计算机软件业。
产生自然垄断的最后一个原因就是在网络化的产业中，整个系统的有效运行都需要标准化和一致性。
政府管制自然垄断是因为，自然垄断者相对于竞争者来说，享有极大的成本优势，而且面对的是缺乏价格弹性的需求，所以能大幅度地提高价格，获得巨额垄断利润，导致经济在很大程度上的无效率。
萨缪尔森《微观经济学》(第18版)笔记和课后习题详解(供给与需求的基本原理)【圣才出品】
第3章供给与需求的基本原理3.1 复习笔记一、需求概述1．需求表与需求曲线（1）需求的概念需求是指在一定的条件下，消费者在一系列可能的价格水平下愿意而且能够购买的商品的数量与价格之间的对应关系。
它包含两层含义：消费者既有购买的欲望，又有支付该商品价格的购买能力。
需求表示了消费者在每个价格下消费商品数量的计划。
一般说来，随着商品价格的提高，消费者消费商品的数量减少。
根据定义，如果消费者对某种商品只有购买的欲望而没有购买的能力，就不能算作是需求。
需求必须是既有购买欲望又有购买能力的有效需求。
所有消费者对一种商品的需求构成该商品的市场需求，它是由一系列可能的价格水平下所有消费者的需求总量所决定的。
（2）需求表需求表是某商品的各种价格和相应的需求数量的数字序列表，把需求表里的数字序列用曲线形式表示出来就是需求曲线。
（3）需求曲线需求曲线是表示商品需求数量与价格之间函数关系的曲线，一般表示需求量的函数关系。
它表明，在其他情况不变时，一个特定群体（在特定情况下也可以指单个的个人）某一特定时期内在各种价格水平下所购买的某种商品的数量。
需求曲线图形以纵轴表示价格，横轴表示商品数量。
市场需求曲线可以通过将在每一价格水平下所有个人的需求量加总而得到。
2．需求法则（1）需求曲线向下倾斜规律需求法则也称为需求曲线向下倾斜规律，是指在其他条件不变的情况下，随着某种商品或劳务的价格上升（或下降），对该商品或劳务的需求量减少（或增加）的规律；也就是说，商品或劳务的价格与其需求量成反比。
需求法则是造成需求曲线斜率为负的原因。
大多数的一般商品都会满足上述需求法则，但现实生活中并非所有商品都会满足需求法则，例如：①吉芬商品，如马铃薯；②炫耀性物品，如钻石。
（2）需求曲线向下倾斜的原因①替代效应：指由商品的价格变动所引起的商品相对价格的变动，进而由商品的相对价格变动所引起的商品需求量的变动。
—种商品的价格下降将引起消费者用该种商品去替代那些价格未下降或上升的商品。
萨缪尔森经济学Economics第十八版 18th 课后概念、习题答案4
C H A P T E R 4A p p l i c a t i o n s o fS u p p l y a n d D e m a n dCHAPTER OVERVIEW AND TEACHING TIPSIn Chapter 3 you explained the laws of supply and demand, and you familiarized students with the effects of changes in supply and demand. This leads naturally to the related question, “By how much?” How large are the responses to changes in the market, and on what does this responsiveness depend? This chapter introduces students to the concept of elasticity and exposes them to two types of elasticities: price elasticity of demand and price elasticity of supply. These concepts are difficult for students, particularly for those who have math anxiety. Emphasize the importance of percent- age changes in the numerator and denominator of the elasticity equations, and distinguish between price elasticity of demand and the slope of the demand curve. Do not hesitate to spend class time working through examples that illustratethe relationships between the price elasticity of demand and supply, and the demand and supply curves.The final section of the chapter provides students with the opportunity to apply market analysis and elasticity concepts in the arena of public policy-making. Distinguish carefully between the party who writes the check to the gov- ernment for a tax and the party who bears the economic burden of taxation. Just because taxes are often “paid” to the government by sellers does not mean that the sellers actually experience reduced incomes when new taxes are imposed. Price ceilings and price floors describe another type of government intervention into the operation of markets.LEARNING OBJECTIVES1. Define the term price elasticity of demand.2. Discuss the factors that determine whether price elasticity of demand is elastic, unitary-elastic, orinelastic, and compare consumer behavior in the short run and the long run. Describe elastic and inelastic regions that exist along any demand curve.3. Calculate price elasticity of demand using a method of averages, ant interpret your result.4. Explain, using diagrams, the relationship between total revenue and price elasticity of demand.5. Define the term price elasticity of supply.6. Discuss the factors that determine whether price elasticity of supply is elastic, unitary-elastic, orinelastic, and compare consumer behavior in the short run and the long run.7. Calculate price elasticity of supply using a method of averages, and interpret your result.8. Apply supply, demand, and elasticity concepts to the following situations and markets: (a) agriculture markets, (b)gasoline taxes, (c) minimum wages, and (d) energy price controls.SUGGESTED ANSWERS TO QUESTIONS IN THE TEXT1. A good harvest shifts a fairly inelastic supply curve to the right. Equilibrium moves down alonga relatively inelastic demand curve to support a (much) lower price, and hence lower farm revenues.2. More price elastic: perfume and ice cream because they are closer to luxuries than necessities; chocolate icecream and automobiles because there are more substitutes for these goods than there are for ice cream and automobile tires, respectively.3. Demand would be inelastic, with E D = .5.4. Assume that demand and supply both show some price elasticity.a. Output and price up along supply curve (demand-curve shift), assuming apartments are normal goods.b. Output down and price (paid by renters) up along demand curve (supply shift).c. If this price is below equilibrium (which makes sense if the policy is to have an impact), this is a price ceiling,established to protect buyers. A shortage of apartments will result, with quantity demanded greater than quantity supplied.1516 C HAPTER 4: A PPLICATIONS OF S UPPLY AND D EMAND d. Output up and price down along demand curve (supply shift).e. Output down and price up along demand curve (supply shift).5. According to the text, a 10% increase in the minimum wage would decrease employment of teenagers between 1and 3 percent. The impact on the adult population is even smaller. Thus, income for teenagers and adults would rise. Thus, if I had to make a decision on increasing the minimum wage, and if raising wages for low-wage workers were important to me, I would certainly vote to increase the minimum.6. Minimum wages can increase the quantity of labor supplied and decrease the quantity of labor demanded. Abind- ing minimum wage therefore creates a surplus of labor. Price ceilings can have the opposite effect. A legal maximum interest rate can lead to a shortage of loanable funds, with lenders willing to supply fewer funds than demanders would like to borrow. See Figure 4-1 for an illustration of the impact of a minimum wage on the marketfor unskilled workers when the demand is relatively elastic for those workers. Area B is lost due to the minimumwage, area A is gained, resulting in smaller earnings overall.Figure 4-1 7. The $2000 tariff on imported automobiles will act like a tax in that market, shifting the supply curve to the left by the amount of the tariff and resulting in lower quantities exchanged at a higher price. This will encourage con- sumers to substitute into autos produced by domestic firms, increasing the demand for those cars. The price and quantity exchanged of autos produced by domestic firms will rise, resulting in greater revenues for domestic automakers. 8. a. Supply down by 5 percent with elasticity of 0.05 means that price must increase by 100 percent. b. Elasticity is a ratio of percentages; it is thus unitless. c. Supply down by 50 percent means that price must increase by 100 percent to keep the price elasticity equal to 0.5. Crime should increase if addicts steal to feed their habits. A successful rehab program would shift demand in; quantity would fall by 50 percent and price would stay the same (the shifts would match). d. This policy would shift the supply of pork to the left, raising market prices. If, as argued in this chapter, the demand for agriculture products is inelastic, higher prices will result in higher farm incomes. e. The income rectangle is larger after the minimum wage is increased. This tells us that the price elasticity of demand for unskilled workers if very low; changes in the wage have little impact on the quantity of these laborers demanded. 9. a. See diagram. Figure 4-2C HAPTER 4: A PPLICATIONS OF S UPPLY AND D EMAND 17b. The vacancy rate will fall, there will be a shortage of apartments at the ceiling price.Figure 4-3c. The government might subsidize landlords in order to provide higher compensation for apartments.d. Rent controls limit the amount of compensation that landlords can receive for their property. This limits theirwillingness to maintain property, thus giving rise to the concerns of the European critic.10. The demand curve is given by P = 6.56 -.08Q, the supply curve is perfectly elastic at a price of $2.40 and then at aprice of $2.80. See diagram. The appropriate constant elasticity demand curve is Q = 87.2P-59.Figure 4-4DISCUSSION QUESTIONS1. Define the term elasticity. How does this concept help to explain the general shape and slope of a demand curve?2. True or false: The price elasticity of demand changes as price changes along a linear demand curve.Carefully explain your answer.3. If price elasticity of demand changes along a demand curve, how can we say that a demandcurve is relatively elastic or inelastic? Explain.4. It is easy to understand why a large harvest of corn should lower the per unit price. Explain how that could actuallylower the total receipts farmers get from the corn harvest.5. Oil prices increased more than tenfold between 1973 and 1981 as a result of strategies employed by OPEC, an inter-national cartel. Are you surprised that even the richest societies chose to conserve their oil and related energy products? How might people conserve and economize when gasoline, heating fuels, and electricity have become more expensive per unit? How might the increase in gasoline prices in summer 2000 affect behavior?6. “Any demand curve is almost certain to have both an elastic and an inelastic range.” Can you give an exception? Isit realistic through the range of all prices and quantities?7. How does the introduction of the time element affect price elasticities of supply and demand?18 C HAPTER 4: A PPLICATIONS OF S UPPLY AND D EMAND 8. “Knowing how to calculate the slope of a straight line enables you to calculate the elasticity for any point on anycurve.” Discuss the relationship between price elasticity of demand and the slope of the demand curve.9. What is the difference between the price elasticity of demand and the price elasticity of supply?10. Governments interested in maximizing their total revenue have often taxed products like salt, tobacco, andalcohol. What does this suggest about the elasticity of demand for these goods? Why would they be good targets for taxation?11. Evaluate the following charge: If the government grants an industry a subsidy of $1 per unit and the price does notfall by the full $1, then the industry is cheating the consumer.12. Under what circumstances might black markets arise? What can be done about them? Are black markets necessari-ly bad?13. Suppose the government wishes to set a lower bound on the price of wheat. Compare and contrast the methods itcan use to achieve this goal with respect to the what, how, and for whom questions.14. Many economists are against minimum-wage laws. Discuss why a legal minimum wage set above equilibriummay lead to unemployment. How do the price elasticities of demand and supply help to determine the extent of this unemployment? Can people who earn lower wages be helped in ways that will not lead to unemployment?(Think about both sides of the market as you answer this question.)15. According to some estimates, the total revenues from the sale of pornography in Denmark declined by 25 percent inthe year immediately following the liberalization of the censorship laws. From this evidence, some sociologists have determined that legalizing this type of activity reduces the demand for it. Do you agree?Why or why not? What effects on the supply side might be deduced?16. What factors are likely to make demand for a commodity either elastic or inelastic? What factorsare likely to influence elasticity of supply?17. How do you think a minimum-wage law might affect the market for unskilled labor? For skilled labor?ESSAY QUESTIONS1. The Brazilian government used to destroy a substantial portion of its coffee harvest to increase its revenue fromcoffee exports. What conditions are essential to make this type of policy economically beneficial for the country? 2. A witness in a recent congressional hearing argued that consumers budgeted a fixed amount of expenditure for theproducts of his industry. Assuming his statements to be correct, what is the elasticity of demand for the industry’s products? Why?3. On a straight-line demand curve, point out the ranges where demand is elastic, inelastic, and unitary elastic.Why does the elasticity vary along a straight-line demand curve? Draw a graph that relates these regions to the slope of a total revenue curve.4. Consider two markets, the apple market and the orange market. Draw a supply-and-demanddiagram for each market. Indicate the equilibrium price and quantity of P0 and Q0, respectively.a. If there were an outbreak of an apple disease, illustrate the new equilibrium price and quantity in the applemarket by P1, Q1.b. How might this affect the orange market? Show these effects on your diagram.Redraw the original diagram for the apple market. Now suppose the government wishes to encourage the production of apples and gives the producers of apples a subsidy of x dollars per apple.c. Indicate the new equilibrium price and quantity in the apple market by P2, and Q2, respectively.d. Explain whether the equilibrium price will increase or decrease by more or less than the amount of the subsidyper apple.e. Shade in the total subsidy the government will pay to the apple industry each period.f. Describe how this subsidy will be shared between consumers and producers.5. The supply and demand curves for wheat are very inelastic. Those for sugar are very elastic. If a sales tax of $1per unit is put on each of these goods, in which case will the incidence fall largely on the consumer and in which case largely on the producer? In which case is the revenue raised by the tax higher? Use diagrams to illustrate your answers.6. Elasticity is the same as slope. Comment on the validity of this statement.7. Explain the relationship between the elasticity of demand and revenue of a business.。
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第11章不确定性和博弈论
11.1 复习笔记
一、风险和不确定性经济学
1．投机原理
（1）投机的原因及含义
一般而言，市场上的产品价格每月都在波动，劳动、土地、机器和燃料等投入品的价格常常有很高的不稳定性；竞争对手的行为也无法提前预知。
企业当前投资的实质在于为未来的利润积攒财富，以备应对未来的不确定性。
投机包括对有价值物品或商品的买卖，是从市场价格的波动中谋取利益的一种活动。
通常，一个投机者现在买入一种商品，为的是将来在这种商品价格上涨时卖出，以期获得利润。
投机是一种风险行为，即使是有经验的投机者有时也会因为错误的估计而遭受损失。
（2）投机的形式
①套利和地区价格形式
最简单的投机活动是降低或消除地区差价。
在这种情况下，商人在某一市场买入的同时，以较高的价格在另一市场卖出。
这种活动被称为套利，它在一个市场上买入一种商品或资产，为的是马上在另一个市场上卖出，从而在价差中获得利润。
套利活动就是同时与不同地区的经纪人通话，以找出微小的差价，力图通过低价购买和高价售出来获取利润。
套利活动有助于拉平完全相同的产品在不同市场上的价格差别。
套利体现了“看不见的手”的作用，即在获取利润的动机的诱惑下，消除不同市场价格差异，促进市场功能更加有效地发挥作用。
投机致力于确立某种不同的时间和空间上的价格范式。
但未来难以预测，从而使这种价格范式不那么完美，即总是处在一种不断受到破坏而自身又不断地重新构建的均衡之中。
投机揭示了看不见的手的法则在起作用。
通过拉平供给量和价格，投机实际上在提高经济效率。
通过将商品从数量丰盛的时期转移到数量稀缺的时期，投机商在价格和边际效用低的市场购进商品，又在价格和边际效用高的地方卖出。
投机商们在追求他们私人利益（利润）的同时，提高了公共经济福利（总效用）。
③投机的经济作用和影响
投机市场不仅从时间上和空间上促进了价格及配置形式的改善，还有助于风险的转移。
这些任务都是由那些想从价格变动中获利的投机商所完成的。
事实上，这表明了看不见的手在起作用，即将商品从其数量丰盛（价格低）时期向数量稀缺（价格高）时期进行重新配置。
理想的投机对于减少消费量的变化有重要的作用，而且，在个人都表现出边际效用递减的情况下，投机可以提高总体效用和分配效率。
投机活动的经济作用就是将各种商品从数量丰富的时期“运送”至商品稀缺的时期。
这种“运送”将会跨越空间、时间或者不确定的自然因素。
具体而言，投机就是在商品数量充足、价格低的时间或地点买进，然后在商品数量稀缺、价格高的时间或地点卖出。
投机市场的一个重要功能是让人们通过套期保值分摊风险。
套期保值是通过对所拥有的一种商品作对冲交易来降低风险。
套期保值通过作对冲交易来回避价格波动的风险。
2．风险、不确定性和保险
（1）人们的风险偏好
一般地说，人们都不愿冒风险，总是想要避免各种消费和收入的不确定性。
在其他条件相同的情况下，相对于不确定的消费水平来说，人们更喜欢做有把握的事情。
也就是说，
的活动能够导致经济福利的改善。
一般说来，若一个人为损失一定量的收入而产生的痛苦感大于他为得到同等数量的收入而产生的满足感，则他就是一个风险规避者。
（2）保险与风险分摊
尽管风险规避者都要努力避免风险，但风险并不会因此而被消除。
市场机制通过风险分摊来应付各种风险。
所谓风险分摊就是将对一个人来说可能是很大的风险分摊给许多人，从而使每个人所承担的风险很小。
风险分摊的主要形式是保险。
保险公司通过集中各种不同的风险来分摊风险：它为数以百万计的住宅、生命或汽车提供保险。
保险公司的优势在于，对个人来说是难以预料的事件，对整个人群来说则具有很强的可预见性。
保险将风险从风险规避者或风险较大者的一方，转移到偏好风险者或较容易承担风险者的一方，保险能够减轻和分散风险。
3．资本市场与风险分担
分散风险另一种方式是经由资本市场来进行。
有形资本的资金所有权可以通过企业所有权这个媒介，将风险在很多的所有者之间进行分摊。
通过将风险性资产的所有权分散到众多的所有者身上，资本市场便可以分散风险，并且能够提供比单个的所有者大得多的投资和承担大得多的风险。
4．信息市场失灵
由于市场失灵，在现实中会出现许多不确定性和风险。
市场失灵的两个重要因素是：“逆向选择”和“道德风险”。
当存在这些因素时，市场就可能会给出错误的信号，从而破坏激励机制，甚至有时还会瓦解市场机制。
在这样一些场合，政府很可能就会介入并提供社会保险。
（1）保险市场的失灵
保险市场正常运转需要一些条件。
首先，必须存在大量的随机事件。
只有这样，保险公司才能将各种不同的随机事件合并起来，并将风险分散，从而使那些对个人来说是很大的风险，能够变成对许多人来说是很小的风险。
其次，各随机事件还必须是相对独立的。
任何一家谨慎的保险公司都尽力使其承保的范围分散到各种不同的和相对独立的风险上。
再者，保险公司对于这样的随机事件必须具有足够的经验，这样，才能准确地预期和估计损失。
最后，相对来讲，保险必须排除道德风险。
当保险减小了个人躲避和防止风险的动力，从而扭曲了损失发生的概率时，便会发生道德风险的问题。
除了道德风险会导致保险市场失灵以外，逆向选择也会导致市场失灵。
由于逆向选择，人们得不到私人保险，或者，会出现令人难以接受的定价方式。
当风险最大者成为最可能购买保险的人群时，逆向选择便发生了。
（2）社会保险
当市场失灵严重以致私人保险不能提供足够的保险项目时，这时就需要由政府提供的强制性社会保险来发挥作用。
政府具有税收和调节权力，加上有能力通过扩大保险的覆盖面以避免逆向选择，因而政府的保险能够增进社会福利。
社会保险的一个重要例子是失业保险。
首先，保险公司不能提供失业保险，因为道德风险很严重（如果获益丰厚的话，人们很可能选择失业）；其次，存在严重的逆向选择（那些经常失业的人更愿意多购买失业保险）；再者，每个人的失业风险的增减并不独立（它们通常随经济周期的衰退而同步出现）；最后，人们在失业时需要有一张安全网，以减轻失业的痛苦。
因此，政府经常介入和提供失业保险。
政府不能防止道德风险问题，但却能借助全面覆盖保险范围的社会保险计划来防止逆向选择。
社会保险的另一个重要例子是老年人医疗保险。
由于健康的人不愿投保，而投保人主
要都是高成本人群，因而会出现逆向选择的问题。
逆向选择对于老年人更加严重，因为生命中最后一年的医疗费用很可能要占人生总医疗费用的较大比例。
为了避免逆向选择，政府对老年人提供全面的保险计划，医疗费用由保险费和全部在职人员所交纳的税金来加以支付。
二、博弈论
1．博弈论及其基本概念
（1）博弈论的含义
博弈论所分析的是两个或两个以上的参与者选择能够共同影响每一参加者的行动或策略的方式。
经济学家利用博弈论来研究垄断者们的互动、工会与管理层的争议、国际贸易政策、国际环境协议、名誉以及其他诸多问题。
博弈论还可以用来研究政治、福利和日常生活。
（2）博弈论的基本概念——以价格战为例
①博弈的描述
假如市场上的供给只由两个企业来提供，它们正在决定是否进行毁灭性的低价格经济战。
每一企业都具有相同的成本和需求结构，而且每个企业都可以选择运用正常的价格，或采取低于边际成本的价格，从而迫使对手破产，以占领整个市场。
双寡头垄断博弈的特点是，企业利润的获得既取决于自己的战略，也取决于对手的战略。
如图11-1所示，体现两个企业或两个人之间相互作用的有用工具是双方的支付矩阵，这是一种表示双方采取的策略和回报状况的方法。
在支付矩阵中，每一个企业可以在自己的行和列中选择战略。
每个企业有两种选择：是运用正常的价格，还是采取低价格挑起价格战。
将每个竞争者所选择的两种决策组合起来，可以得到四种结果：A是两个企业选择
正常价格的结果，D 是双方均选择低价战价格的结果；B 和C 则是一方采用正常价格，而另一方采取低价战价格的结果。
图11-1 价格战的支付矩阵
每1格子中的数字代表了两个企业的回报情况，即每个企业在四种结果中的获利情况。
左下角的数字是对弈者Amazing 公司的获利；右上角的数字则表示nEwBooks 公司的获利。
由于参与企业是一致的，因而，双方的获利情况势必具有对称性。
②策略选择
博弈论的指导思想是：假设一方在研究另一方的策略，并采取追求自身最大利益行动的时候，另一方如何选择最有效的策略。
在双寡头垄断价格战博弈中，这两家公司在图11-1中的A 格有着共同的最大利益。
当双方都运用正常价格战略时，每个企业将各赚10美元。
而在另一个极端，是双方都采用削价战略、都会遭受最大损失的情况。
在上述两种情况之间，存有两种有趣的战略，即只有一方选择发动价格战。
例如，在结果C 中，nEwBooks 公司坚持正常的价格战略，而Amazing 公司却采取降价战略。
于是，Amazing 公司拥有了市场，可它却损失了大笔的金钱，因为它的售价低于成本。
nEwBooks 公司一直以正常价格销售，而不是对Amazing 公司的策略以牙还牙，其处境反倒要好一些。
③占优均衡。