曼昆经济学2像经济学家一样思考(英文版)

1、 2015 CUFEC H A P T E R2What 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 循环流量图? What concepts does the diagram illustrate? How is the Production Possibilities Frontier （生产可能性边界） related to opportunity co

2、st? What other concepts does it illustrate?What is the difference between microeconomics and macroeconomics? Between positive and normative （实证分析与规范分析）?1THINKING LIKE AN ECONOMIST2The Economist as Scientist作为科学家的经济学家作为科学家的经济学家Economists play two roles:1. Scientists（科学家）: try to explain the world（解释世

3、界，Why）2. Policy advisors（政策咨询者）: try to improve it（改造世界，How）In the first, economists employ the scientific method（科学方（科学方法）法）, the dispassionate （不带偏见的） development and testing of theories about how the world works. （利用科学方法解释世界如何运行）科学方法：观察提出理论进一步观察（检测理论）与自然科学不同的是，经济学往往无法做实验关注历史发生的自然实验THINKING LIKE A

4、N ECONOMIST3Assumptions & Models假设假设&模型模型Assumptions simplify the complex world, make it easier to understand.（假设只是为了便于理解：现实太复杂）Example: To study international trade, assume two countries and two goods. Unrealistic, but simple to learn and gives useful insights about the real world.Model: a

5、highly simplified representation of a more complicated reality. （对复杂的现实世界近似描述）Economists use models to study economic issues. （经济学家利用经济学模型来研究问题） THINKING LIKE AN ECONOMIST4Some Familiar ModelsA road map模型类似于地图模型需要在贴近现实和尽量简化之间进行权衡。THINKING LIKE AN ECONOMIST5Some Familiar ModelsA model of human anatom

6、y （人体解剖学） from high school biology classTHINKING LIKE AN ECONOMIST6Some Familiar ModelsA model airplaneTHINKING LIKE AN ECONOMIST7Some Familiar ModelsThe model teeth at the dentists officeDont forget to floss!THINKING LIKE AN ECONOMIST8Our First Model: The Circular-Flow DiagramThe Circular-Flow Diag

7、ram（经济循环图）（经济循环图）: a visual model of the economy, shows how dollars flow through markets among households and firms 经济循环图一个说明货币货币如何通过市场市场在家庭家庭和企业企业之间流动流动的直观经济学模型。Two types of “actors”: households（家庭） & firms Two markets:the market for goods and services （商品与劳务市场）the market for “factors of produc

8、tion” （生产要素市场）THINKING LIKE AN ECONOMIST9Factors of ProductionFactors of production（生产要素）（生产要素）: the resources the economy uses to produce goods & services, includinglabor land capital (buildings & machines used in production)THINKING LIKE AN ECONOMIST10FIGURE 1: The Circular-Flow DiagramHou

9、seholds （家庭）（家庭）: Own the factors of production, sell/rent them to firms for income Buy and consume goods & servicesHouseholds FirmsFirms （企业）（企业）: Buy/hire factors of production, use them to produce goods and services Sell goods & servicesTHINKING LIKE AN ECONOMIST11FIGURE 1: The Circular-F

10、low DiagramMarkets for Factors of ProductionHouseholdsFirms IncomeWages, rent, profitFactors of productionLabor, land, capital SpendingG & S boughtG & S soldRevenueMarkets for Goods（G） & Services（S）THINKING LIKE AN ECONOMIST12经济循环图经济循环图企业企业家庭家庭生产要素生产要素市场市场物品与劳务物品与劳务市场市场支出支出收入收入工资、租金工资、租金

11、和利润和利润收入收入销售商品销售商品和服务和服务购买商品购买商品和服务和服务劳动、土地劳动、土地和资本和资本生产投入生产投入THINKING LIKE AN ECONOMIST13Our Second Model: 生产可能性边界生产可能性边界The Production Possibilities FrontierThe Production Possibilities Frontier （ PPF ）: a graph that shows the combinations of two goods the economy can possibly produce given the av

12、ailable resources and the available technology。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产品数量的各种组合的图形。能生产的产品数量的各种组合的图形。Example: Two goods: computers and wheatOne resource: labor (measured in hours)Economy has 50,000 labor hours per month available for production.PPF ExampleProducing

13、one computer requires 100 hours labor.Producing one ton of wheat requires 10 hours labor.5,00004,0001002,5002501,00040050,000040,00010,00025,00025,00010,00040,0000500050,000EDCBAWheatComputersWheatComputersProductionEmployment of labor hoursTHINKING LIKE AN ECONOMIST15Point on graphProductionCom-put

14、ersWheatA5000B4001,000C2502,500D1004,000E05,000ABCDEPPF ExampleA.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 goods?Why or why not? B.Next, find the point that represents (300

15、 computers, 3500 tons of wheat), label it G. Would it be possible for the economy to produce this combination of the two goods?1617Point F:100 computers, 3000 tons wheatPoint F requires 40,000 hours of labor. Possible but not efficient: could get more of either good w/o sacrificing any of the other.

16、F18Point G:300 computers, 3500 tons wheatPoint G requires 65,000 hours of labor. Not possible because economy only has 50,000 hours.GTHINKING LIKE AN ECONOMIST19The PPF: What We Know So FarPoints on the PPF (like A E)possibleefficient: all resources are fully utilized (资源充分利用)Points under the PPF (l

17、ike F) possiblenot efficient: some resources underutilized (e.g., workers unemployed, factories idle （工厂空闲）) Points above the PPF (like G) not possibleTHINKING LIKE AN ECONOMIST20The PPF and Opportunity CostRecall: The opportunity cost of an item is what must be given up to obtain that item. Moving

18、along a PPF involves shifting 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（斜率）（斜率） of the PPF tells you the opportunity cost of one good in terms of the other. （斜率可以作为机会成本的度量

19、指标）THINKING LIKE AN ECONOMIST21The PPF and Opportunity CostThe slope of a line equals the “rise over the run,” the amount the line rises when you move to the right by one unit.1000100slope = 10Here, the opportunity cost of a computer is 10 tons of wheat.22In which country is the opportunity cost of

20、cloth lower?FRANCEENGLAND23FRANCEENGLANDEngland, because its PPF is not as steep as Frances.THINKING LIKE AN ECONOMIST24Economic Growth （经济增长经济增长） and the PPFWith additional resources or an improvement in technology（资源增加或者技术提升）, the economy can produce more computers,more wheat, or any combination i

21、n between. Economic growth shifts the PPF outward.25The Shape of the PPFThe PPF could be a straight line, or bow-shaped （弓形）Depends on what happens to opportunity cost as economy shifts resources from one industry to the other.If opp. cost（机会成本） remains constant, PPF is a straight line. （机会成本是常数，PPF

22、为直线）(In the previous 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.（通常情况：机会成本递增导致PPF为弓形） THINKING LIKE AN ECONOMIST26Mountain BikesBeerAs the economy shifts resources from beer to mountain bikes:

23、PPF becomes steeperopp. cost of mountain bikes increases Why the PPF Might Be Bow-Shaped 生产可能性边界为何有时候是弓形的生产可能性边界为何有时候是弓形的THINKING LIKE AN ECONOMIST27AAt point A, most workers are producing beer, even those that are better suited to building bikes.（太多的资源生产啤酒，生产效率低下）So, do not have to give up much bee

24、r to get more bikes.Mountain BikesBeerAt A, opp. cost of mtn bikes is low.Why the PPF Might Be Bow-Shaped 生产可能性边界为何有时候是弓形的生产可能性边界为何有时候是弓形的THINKING LIKE AN ECONOMIST28BAt B, most workers are producing bikes. The few left in beer are the best brewers.（最好的啤酒制造者）Producing more bikes would require shifti

25、ng some of the best brewers away from beer production, would cause a big drop in beer output. Mountain BikesBeerAt B, opp. cost of mtn bikes is high.Why the PPF Might Be Bow-Shaped 生产可能性边界为何有时候是弓形的生产可能性边界为何有时候是弓形的随着生产登山车的劳动投入增加，大量高效率生产啤酒的工人不能再生产啤酒，转而生产登山车，从而机会成本逐渐增加。THINKING LIKE AN ECONOMIST29So, P

26、PF is bow-shaped when different workers have different skills, different opportunity costs of producing one good in terms of the other.（不同工人生产技能不同）The PPF would also be bow-shaped when there is some other resource, or mix of resources with varying opportunity costs（未考虑的其他资源导致的机会成本存在差异）(E.g., differe

27、nt types of land suited for different uses). (土地资源opp.cost是不同的)Why the PPF Might Be Bow-Shaped 生产可能性边界为何有时候是弓形的生产可能性边界为何有时候是弓形的THINKING LIKE AN ECONOMIST30The PPF: A SummaryThe PPF shows all combinations of two goods that an economy can possibly produce, given its resources and technology. （给定技术、资源，

28、最大化生产两种产品的全部可能组合）The PPF illustrates the concepts of tradeoff （权衡取舍）（权衡取舍）and opportunity cost（机会成机会成本）本）, efficiency （效率）（效率）and inefficiency （非效（非效率）率）, unemployment（失业）（失业）, and economic growth（经济增长）（经济增长）. A bow-shaped PPF illustrates the concept of increasing opportunity cost. （递增的机会成本）（递增的机会成本

29、） THINKING LIKE AN ECONOMIST31Microeconomics and Macroeconomics微观经济学微观经济学 和和 宏观经济学宏观经济学Microeconomics is the study of how households and firms make decisions and how they interact in markets. （微观经济学研究家庭和企业如何做决策，微观经济学研究家庭和企业如何做决策，以及他们在市场中如何相互作用以及他们在市场中如何相互作用）Macroeconomics is the study of economy-wid

30、e phenomena, including inflation, unemployment, and economic growth. （宏观经济学研究经济总体现象，宏观经济学研究经济总体现象，包括通胀、失业、经济增长问题等等包括通胀、失业、经济增长问题等等）These two branches of economics are closely intertwined （紧密联系）（紧密联系）, yet distinct （有区别）（有区别） they address different questions. The Economist as Policy Advisor作为政策顾问的经济学

31、家作为政策顾问的经济学家As scientists, economists make positive statements（实证表（实证表述）述）, which attempt to describe the world as it is. 实证表述指的是解释解释经济现象，这是经济学家作为科学家的一种角色As policy advisors, economists make normative statements, 规范表述规范表述which attempt to prescribe how the world should be. 规范表述试图描述世界应该应该是什么样的观点。Positi

32、ve statements can be confirmed or refuted, normative statements cannot. （实证表述可以被证实或否定，规范表述则不能）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. 3233Which of these statements are “p

33、ositive” (实证) and which are “normative” （规范）? How can you tell the difference?a.Prices rise when the government increases the quantity of money. （政府增加货币数量，价格会上涨）b. The government should print less money. （政府应该少发货币）c. A tax cut （减税）is needed to stimulate the economy （刺激经济）. d.An increase in the price

34、 of burritos （卷饼） will cause an increase in consumer demand for video rentals （录像租赁）.34a. 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 judgm

35、ent, cannot be confirmed or refuted.35c. 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 for video rentals.Positive describes a relationship. Note that a statement need not be true to be

36、positive.Why Economists Disagree为什么经济学家意见分歧为什么经济学家意见分歧pThey may disagree on theories about how the world works.（实证表述不一样） 对关于世界如何运行的理论看法不同。pThey may hold different values and, thus, different normative views. （规范表述不一样） 他们可能有不同的价值观，从而有不同的规范性观点。THINKING LIKE AN ECONOMIST37Propositions about Which Most

37、Economists Agree (and % who agree)continued1. 租金上限减少了可得到的住房数量和质量。（93）2. 关税和进口配额通常降低了普遍的经济福利。（93）3. 有伸缩性和浮动性的汇率提供了一种有效的国际货币协定。（90）4. 财政政策 例如，减税和（或）增加政府支出 对低于充分就业的经济有重要的刺激效应。（90）5. 如果要平衡联邦预算，应该在经济周期中而不是每年中来实现。（85）THINKING LIKE AN ECONOMIST38Propositions about Which Most Economists Agree (and % agreeing)6. 现金转移支付