1、Thinking Like An Economist,2,像经济学家一样思考,In this chapter, look for the answers to these questions:,What are economists two roles? How do they differ? What are models? How do economists use them?What are the elements of the Circular-Flow Diagram? What concepts does the diagram illustrate? How is the Pr
2、oduction Possibilities Frontier related to opportunity cost? What other concepts does it illustrate?What is the difference between microeconomics and macroeconomics? Between positive and normative?,1,2,本章将探索这些问题的答案：,经济学家的两种角色是什么？它们有什么不同？什么是模型？经济学家怎么使用它们？循环流量图的构成要素有哪些？流量图想要说明什么问题？生产可能性边界与机会成本有什么联系？它还
3、表示了什么其他概念？微观经济学与宏观经济学有什么不同？实证经济学与规范经济学呢？,2,3,The Economist as Scientist,Economists play two roles:1. Scientists: try to explain the world2. Policy advisors: try to improve itIn the first, economists employ the scientific method, the dispassionate development and testing of theories about how the wor
4、ld works.,4,作为科学家的经济学家,经济学家扮演的两种角色： 科学家：试图解释世界 政策顾问：尝试改善世界作为科学家，经济学家使用科学方法冷静地建立并检验有关世界如何运行的各种理论,5,Assumptions & Models,Assumptions simplify the complex world, make it easier to understand. Example: To study international trade, assume two countries and two goods. Unrealistic, but simple to learn and
5、 gives useful insights about the real world.Model: a highly simplified representation of a more complicated reality. Economists use models to study economic issues.,6,假设与模型,假设可以简化复杂的世界，使之更容易理解比如：为了研究国际贸易，假设世界上只由两个国家组成，而且每个国家只生产两种产品。尽管在实际中是不真实的，但这可以帮助我们更方便的学习和理解现实世界模型：一个复杂现象的高度简化 经济学家使用模型来研究经济问题,7,So
6、me Familiar Models,A road map,8,Some Familiar Models,A model of human anatomy from high school biology class高中生物课堂上的人体解剖模型,9,Some Familiar Models,A model airplane,10,Some Familiar Models,The model teeth at the dentists office,11,Economic Models,Economic model A simplified version of some aspect of e
7、conomic life used to analyze an economic issue.To develop a model, economists generally follow these steps:Decide on the assumptions to be used in developing the model.Formulate a testable hypothesis.Use economic data to test the hypothesis.Revise the model if it fails to explain properly the econom
8、ic data.Retain the revised model to help answer similar economic questions in the future.,Economic variable Something measurable that can have different values, such as the wages of software programmers.,12,Our First Model: The Circular-Flow Diagram,The Circular-Flow Diagram: a visual model of the e
9、conomy, shows how dollars flow through markets among households and firmsTwo types of “actors”: householdsfirms Two markets:the market for goods and services the market for “factors of production”,13,我们的第一个模型：循环流量图,循环流量图：一个说明货币如何通过市场在家庭与企业之间流动的直观经济模型两类主体：家庭企业两个市场：物品与劳务市场生产要素市场,14,Factors of Producti
10、on,Factors of production: the resources the economy uses to produce goods & services, includinglabor land capital (buildings & machines used in production),15,生产要素,生产要素：经济体用来生产物品与劳务的资源，包括：劳动土地 资本（建筑物和用于生产的机器）,16,FIGURE 1: The Circular-Flow Diagram循环流量图,Households:Own the factors of production, sell/
11、rent them to firms for incomeBuy and consume goods & services,Firms:Buy/hire factors of production, use them to produce goods and servicesSell goods & services,17,图1 ：循环流量图,家庭:拥有并出售或出租生产要素给企业以获得收入购买并消费物品与劳务,企业：购买或雇佣生产要素并用以生产物品与劳务出售物品与劳务,18,FIGURE 1: The Circular-Flow Diagram,19,图1 ：循环流量图,20,Our Seco
12、nd Model: The Production Possibilities Frontier,The Production Possibilities Frontier (PPF): a graph that shows the combinations of two goods the economy can possibly produce given the available resources and the available technology Example: Two goods: computers and wheatOne resource: labor (measur
13、ed in hours)Economy has 50,000 labor hours per month available for production.,0,21,我们的第二个模型：生产可能性边界,生产可能性边界 （PPF）：表示在可得到的生产要素与生产技术既定时，一个经济所能生产的两种产品数量的各种组合的图形例如： 两种物品：电脑与小麦一种资源：劳动力（以小时为单位来衡量）每月经济有50，000个劳动小时可用于生产,0,PPF Example,Producing one computer requires 100 hours labor.Producing one ton of whea
14、t requires 10 hours labor.,0,23,生产可能性边界的例子,生产一台电脑需要100个小时的劳动生产一吨小麦需要10个小时的劳动,0,24,A,B,C,D,E,PPF Example,25,A,B,C,D,E,生产可能性边界的例子,A.On the graph, find the point that represents (100 computers, 3000 tons of wheat), label it F. Would it be possible for the economy to produce this combination of the two
15、goods?Why or why not? B.Next, find the point that represents (300 computers, 3500 tons of wheat), label it G. Would it be possible for the economy to produce this combination of the two goods?,A C T I V E L E A R N I N G 1 Points off the PPF,26,27,A.在图上找出代表（100台电脑，3000吨小麦）的点，并标作F。经济能生产出这样的两种产品数量组合吗？
16、为什么？B. 接下来，找出代表（300台电脑，3500吨小麦）的点，并标作G。经济能生产出这样的两种产品组合吗？为什么？,主动学习 1 不在生产可能性边界上的点,27,A C T I V E L E A R N I N G 1 Answers,28,Point F:100 computers, 3000 tons wheat,Point F requires 40,000 hours of labor. Possible but not efficient: could get more of either good w/o sacrificing any of the other.,29,主
17、动学习 1 参考答案,29,点 F:100台电脑, 3000吨小麦,点 F 需要40,000个小时的劳动。能够但没有效率：不用减少任何物品的生产便能获得更多的两种物品,A C T I V E L E A R N I N G 1 Answers,30,Point G:300 computers, 3500 tons wheat,Point G requires 65,000 hours of labor. Not possible because economy only has 50,000 hours.,31,主动学习 1 参考答案,31,点 G:300 台电脑, 3500 吨小麦,点G需要
18、65，000个小时的劳动，因为经济只有50，000个劳动小时，所以不可能。,32,The PPF: What We Know So Far,Points on the PPF (like A E)possibleefficient: all resources are fully utilizedPoints under the PPF (like F) possiblenot efficient: some resources underutilized (e.g., workers unemployed, factories idle) Points above the PPF (like
19、 G) not possible,33,关于生产可能性边界目前为止我们所知的内容,在生产可能性边界上的点（A-E)能够达到有效率：所以资源都已经充分利用在生产可能性边界以内的点（F）能够达到没有效率：一些资源没有充分利用（比如，工人失业，厂房闲置等）在生产可能性边界以外的点（G）不能达到,34,The PPF and Opportunity Cost,Recall: The opportunity cost of an item is what must be given up to obtain that item.,Moving along a PPF involves shifting
20、resources (e.g., labor) from the production of one good to the other. Society faces a tradeoff: Getting more of one good requires sacrificing some of the other. The slope of the PPF tells you the opportunity cost of one good in terms of the other.,35,生产可能性边界与机会成本,复习：机会成本是为了得到某种东西所必须放弃的东西,沿着生产可能性边界移动
21、意味着将资源（比如劳动）从一种物品的生产转移到另一种物品的生产中社会面临权衡取舍：得到更多的一种物品需要以更少的另一种物品为代价生产可能性边界的斜率告诉我们以一种物品来衡量另一种物品的机会成本,36,The PPF and Opportunity Cost,The slope of a line equals the “rise over the run,” the amount the line rises when you move to the right by one unit.,1000,100,= 10,Here, the opportunity cost of a compute
22、r is 10 tons of wheat.,37,生产可能性边界与机会成本,直线的斜率等于直线的横坐标向右移动一个单位时，直线的纵坐标变化的大小,1000,100,= 10,本图，1台电脑的机会成本是10吨小麦,A C T I V E L E A R N I N G 2 PPF and Opportunity Cost,38,In which country is the opportunity cost of cloth lower?,FRANCE,ENGLAND,39,主动学习 2 生产可能性边界与机会成本,39,在哪个国家布料的机会成本更小？,法国,英格兰,A C T I V E L
23、E A R N I N G 2 Answers,40,FRANCE,ENGLAND,England, because its PPF is not as steep as Frances.,41,主动学习 2 参考答案,41,法国,英格兰,英格兰，因为它的生产可能性边界的斜率没有法国的陡峭,42,Economic Growth and the PPF,With additional resources or an improvement in technology, the economy can produce more computers,more wheat,or any combina
24、tion in between.,Economic growth shifts the PPF outward.,43,The Shape of the PPF,The PPF could be a straight line, or bow-shapedDepends on what happens to opportunity cost as economy shifts resources from one industry to the other.If opp. cost remains constant, PPF is a straight line. (In the previo
25、us example, opp. cost of a computer was always 10 tons of wheat.)If opp. cost of a good rises as the economy produces more of the good, PPF is bow-shaped.,44,生产可能性边界的形状,生产可能性边界可以是直线或曲线取决于经济将资源从一个行业转向另一个行业时机会成本的变化情况如果机会成本不变，那生产可能性边界为一条直线（在上述例子中，1台电脑的机会成本恒为10吨小麦）如果一种物品的机会成本随着生产数量的增多而上升，那生产可能性边界为曲线,45,
26、Why the PPF Might Be Bow-Shaped,As the economy shifts resources from beer to mountain bikes:PPF becomes steeperopp. cost of mountain bikes increases,46,为什么生产可能性边界可能是曲线,当经济把资源从啤酒行业向山地自行车行业转移时：生产可能性边界变得更加陡峭山地自行车的机会成本也不断上升,47,A,Why the PPF Might Be Bow-Shaped,At point A, most workers are producing beer
27、, even those that are better suited to building bikes.So, do not have to give up much beer to get more bikes.,Mountain Bikes,Beer,At A, opp. cost of mtn bikes is low.,48,A,为什么生产可能性边界可能是曲线,在点A，大部分工人都在生产啤酒，即使这些工人更加适合于生产山地自行车。因此，为得到更多的自行车无需放弃太多啤酒,山地自行车,啤酒,在点A,山地自行车的机会成本很小,49,B,Why the PPF Might Be Bow-
28、Shaped,At B, most workers are producing bikes. The few left in beer are the best brewers.Producing more bikes would require shifting some of the best brewers away from beer production, would cause a big drop in beer output.,Mountain Bikes,Beer,At B, opp. cost of mtn bikes is high.,50,B,为什么生产可行性边界可能是
29、曲线,在点B,大部分工人都在生产自行车，留在啤酒行业的工人是最好的酿酒师。生产更多的自行车需要将最好的酿酒师从啤酒行业转移出来，这会使啤酒产量大幅度降低,山地自行车,啤酒,在点B,山地自行车的机会成本很高,51,Why the PPF Might Be Bow-Shaped,So, PPF is bow-shaped when different workers have different skills, different opportunity costs of producing one good in terms of the other. The PPF would also be
30、 bow-shaped when there is some other resource, or mix of resources with varying opportunity costs(E.g., different types of land suited for different uses).,52,为什么生产可能性边界可能是曲线,因此，当不同的工人有不同的技能，多生产1单位物品的机会成本也不同，这使生产可能性边界为曲线当经济中存在一些其他资源，或者机会成本不同的资源混合时，生产可能性边界也可能是曲线（例如，不同类型的土地有不同的用处）,53,The PPF: A Summar
31、y,The PPF shows all combinations of two goods that an economy can possibly produce, given its resources and technology.,The PPF illustrates the concepts of tradeoff and opportunity cost, efficiency and inefficiency, unemployment, and economic growth.,A bow-shaped PPF illustrates the concept of incre
32、asing opportunity cost.,54,生产可能性边界：一个总结,生产可能性边界表示在可得到的生产要素与生产技术既定时，一个经济所能生产的两种产品数量的各种组合,生产可能性边界阐释了权衡取舍与机会成本，效率与无效率，失业和经济增长等的思想,曲状的生产可能性边界意味着递增的机会成本,55,Microeconomics and Macroeconomics,Microeconomics is the study of how households and firms make decisions and how they interact in markets. Macroecono
33、mics is the study of economy-wide phenomena, including inflation, unemployment, and economic growth. These two branches of economics are closely intertwined, yet distinct they address different questions.,56,微观经济学与宏观经济学,微观经济学：研究家庭和企业如何做出决策，以及它们如何在市场上相互交易宏观经济学：研究整体经济现象，包括通货膨胀，失业和经济增长这两个经济学的分支是密切相关的，也
34、有所不同它们研究不同的问题,The Economist as Policy Advisor,As scientists, economists make positive statements, which attempt to describe the world as it is. As policy advisors, economists make normative statements, which attempt to prescribe how the world should be. Positive statements can be confirmed or refute
35、d, normative statements cannot. Govt employs many economists for policy advice. E.g., the U.S. President has a Council of Economic Advisors, which the author of this textbook chaired from 2003 to 2005.,57,58,作为政策顾问的经济学家,作为科学家，经济学家试图做出关于世界是什么样子的实证表述作为政策顾问，经济学家试图做出关于世界应该是什么样子的规范表述实证表述能被证实或证伪，但规范表述则不能政
36、府雇佣许多经济学家来提供政策建议。比如美国总统有一个经济顾问委员会，本书的作者即是2003-2005经济顾问委员会的主席,58,A C T I V E L E A R N I N G 3 Identifying positive vs. normative,59,Which of these statements are “positive” and which are “normative”? How can you tell the difference?a.Prices rise when the government increases the quantity of money. b
37、.The government should print less money. c.A tax cut is needed to stimulate the economy. d.An increase in the price of burritos will cause an increase in consumer demand for video rentals.,60,主动学习 3 区分实证表述与规范表述,60,下列表述哪些属于实证表述，哪些属于规范表述？为什么？ a. 当政府增加货币数量时，物价上涨b. 政府应该印刷更少的货币c.为刺激经济，政府应该减税d.墨西哥卷价格上涨会导致
38、消费者录像租赁需求增加,A C T I V E L E A R N I N G 3 Answers,61,a.Prices rise when the government increases the quantity of money. Positive describes a relationship, could use data to confirm or refute.b.The government should print less money. Normative this is a value judgment, cannot be confirmed or refuted.
39、,62,主动学习 3 参考答案,62,a.当政府增加货币数量时，物价上涨实证表述描述了一种关系，可以通过数据来证实或者证伪b.政府应该印刷更少的货币规范表述这是一个价值判断，不能被证实或证伪,A C T I V E L E A R N I N G 3 Answers,63,c.A tax cut is needed to stimulate the economy. Normative another value judgment.d.An increase in the price of burritos will cause an increase in consumer demand f
40、or video rentals.Positive describes a relationship. Note that a statement need not be true to be positive.,64,主动学习 3 参考答案,64,c.为刺激经济，政府应该减税规范表述另一个价值判断d.墨西哥卷的价格上涨会导致消费者录像租赁需求增加实证表述描述一种关系 注意实证表述并不一定需要是正确的,65,Why Economists Disagree,Economists often give conflicting policy advice. They sometimes disagr
41、ee about the validity of alternative positive theories about the world. They may have different values and, therefore, different normative views about what policy should try to accomplish. Yet, there are many propositions about which most economists agree.,66,经济学家意见分歧的原因,经济学家经常提供相互矛盾的建议他们可能对世界如何运行的不
42、同实证理论的正确性看法不一致 他们可能有不同的价值观，因此对政策应该努力实现的目标有不同的规范观点然而，也有许多大多数经济学家一致同意的主张,67,Propositions about Which Most Economists Agree (and % who agree),A ceiling on rents reduces the quantity and quality of housing available. (93%)Tariffs and import quotas usually reduce general economic welfare. (93%)The United
43、 States should not restrict employers from outsourcing work to foreign countries. (90%)The United States should eliminate agriculture subsidies. (85%),continued,68,大多数经济学家一致同意的主张（以及持赞同意见经济学家所占的百分比）,租金上限降低了可得到的住房的数量和质量(93%)关税和进口配额通常降低了总体经济福利（93%）美国不应该限制雇主将工作外包给其他国家（90%）美国应该取消农业补贴（85%）,69,Propositions
44、 about Which Most Economists Agree (and % agreeing),The gap between Social Security funds and expenditures will become unsustainably large within the next fifty years if current policies remain unchanged. (85%)A large federal budget deficit has an adverse effect on the economy. (83%)A minimum wage i
45、ncreases unemployment among young and unskilled workers. (79%)Effluent taxes and marketable pollution permits represent a better approach to pollution control than imposition of pollution ceilings. (78%),70,大多数经济学家一致同意的主张（以及持赞同意见经济学家所占的百分比）,如果现行的政策保持不变，在接下来的50年中社会保障基金与支出之间的缺口会持续扩大并超出承受能力（85%）庞大的联邦预算
46、赤字对经济有不利的影响（83%）最低工资增加了年轻人和不熟练工人的失业（79%）排污税和可交易的污染许可证作为控制污染的方法优于实行污染上限（78%）,FYI: Who Studies Economics?,Ronald Reagan, President of the United StatesBarbara Boxer, U.S. Senator Sandra Day-OConnor, Former Supreme Court JusticeAnthony Zinni, Former General, U.S. Marine Corps Kofi Annan, Former Secreta
47、ry General, United NationsMeg Witman, Chief Executive Officer, eBaySteve Ballmer, Chief Executive Officer, MicrosoftArnold Schwarzenegger, Governor of California, ActorBen Stein, Political Speechwriter, Actor, Game Show HostMick Jagger, Singer for the Rolling Stones John Elway, NFL QuarterbackTiger
48、Woods, GolferDiane von Furstenburg, Fashion Designer,71,72,大多数经济学家一致同意的主张（以及持赞同意见经济学家所占的百分比）,如果现行的政策保持不变，在接下来的50年中社会保障基金与支出之间的缺口会持续扩大并超出承受能力（85%）庞大的联邦预算赤字对经济有不利的影响（83%）最低工资增加了年轻人和不熟练工人的失业（79%）排污税和可交易的污染许可证作为控制污染的方法优于实行污染上限（78%）,CHAPTER SUMMARY,As scientists, economists try to explain the world using
49、 models with appropriate assumptions. Two simple models are the Circular-Flow Diagram and the Production Possibilities Frontier. Microeconomics studies the behavior of consumers and firms, and their interactions in markets. Macroeconomics studies the economy as a whole. As policy advisers, economists offer advice on how to improve the world.,
