宏观经济学的科学.ppt

Chapter 1 The Science of Macroeconomics,第1章 宏观经济学的科学,Learning objectives,This chapter introduces you to the issues macroeconomists study the tools macroeconomists use some important concepts in macroeconomic analysis,学习目标,本章使你学到： 宏观经济学家研究的问题 宏观经济学家使用的工具 宏观经济学分析中的一些重要概念,Important issues in macroeconomics,Why does the cost of living keep rising? Why are millions of people unemployed, even when the economy is booming? Why are there recessions? Can the government do anything to combat recessions? Should it?,宏观经济学的重要问题,为什么生活成本不断上升？ 为什么即使经济繁荣的时候也有数百万人失业？ 为什么所有国家都经历了衰退和萧条？而政府的政策可以怎样减少这些事件发生的频率和减轻其严重程度？,Important issues in macroeconomics,What is the government budget deficit? How does it affect the economy? Why does the U.S. have such a huge trade deficit? Why are so many countries poor? What policies might help them grow out of poverty?,宏观经济学的重要问题（续）,什么是政府预算赤字？它怎样影响经济？ 为什么美国有巨大的贸易赤字？ 为什么那么多国家陷于贫困之中？什么政策可以帮助它们摆脱贫困？,U.S. Gross Domestic Product in billions of chained 1996 dollars,美国国内生产总值 （以1996年美元价值计，单位：10亿美元）,U.S. Gross Domestic Product in billions of chained 1996 dollars,美国国内生产总值 （以1996年美元价值计，单位：10亿美元）,U.S. Real GDP per Person,U.S Inflation Rate,U.S. Unemployment Rate,Why learn macroeconomics?,The macroeconomy affects societys well-being. example: Unemployment and social problems,为什么学习宏观经济学,宏观经济影响社会福利 例: 失业和社会问题,Unemployment and social problems,Each one-point increase in the unemployment rate is associated with: 920 more suicides 650 more homicides 4000 more people admitted to state mental institutions 3300 more people sent to state prisons 37,000 more deaths increases in domestic violence and homelessness,失业和社会问题,失业率每增加一个百分点，相关于: 多920个自杀者 多650杀人犯 多4000人进入精神病机构 多3300进监狱 多37,000人死亡 国内暴力和无家可归者增加,Why learn macroeconomics?,The macroeconomy affects societys well-being. example: Unemployment and social problems,The macroeconomy affects your well-being. example 1: Unemployment and earnings growth example 2: Interest rates and mortgage payments,为什么学习宏观经济学？,宏观经济影响社会福利 例: 失业和社会问题,宏观经济影响你的福利 例 1: 失业和收入增长 例2: 利率和贷款利息支出,Unemployment and earnings growth,失业和收入增长,Interest rates and mortgage payments,For a $150,000 30-year mortgage:,$11,782,$981,6.84%,Dec 2012,$12,771,$1064,7.65%,利率和抵押贷款利息支出,对于一个 $150,000 30年的抵押贷款:,$11,782,$981,6.84%,Dec 2012,$12,771,$1064,7.65%,Why learn macroeconomics?,The macroeconomy affects societys well-being. example: Unemployment and social problems,The macroeconomy affects your well-being. example 1: Unemployment and earnings growth example 2: Interest rates and mortgage payments,The macroeconomy affects politics & current events. example: Inflation and unemployment in election years,为什么学习宏观经济学,宏观经济影响社会福利. 例： 失业和社会问题,宏观经济影响你的福利。 例1: 失业和收入增长 例 2: 利率和抵押贷款利息支出,宏观经济影响政治和时事 例: 选举年的通货膨胀和失业,Inflation and Unemployment in Election Years,year U rate inflation rate elec. outcome 1976 7.7% 5.8% Carter (D) 1980 7.1% 13.5% Reagan (R) 1984 7.5% 4.3% Reagan (R) 1988 5.5% 4.1% Bush I (R) 1992 7.5% 3.0% Clinton (D) 1996 5.4% 3.3% Clinton (D) 4.0% 3.4% Bush II (R) 2008 high Obama (D),选举年的通货膨胀率和失业率,year U rate inflation rate elec. outcome 1976 7.7% 5.8% Carter (D) 1980 7.1% 13.5% Reagan (R) 1984 7.5% 4.3% Reagan (R) 1988 5.5% 4.1% Bush I (R) 1992 7.5% 3.0% Clinton (D) 1996 5.4% 3.3% Clinton (D) 4.0% 3.4% Bush II (R) 2008 high Obama (D),Economic models,are simplied versions of a more complex reality irrelevant details are stripped away Used to show the relationships between economic variables explain the economys behavior devise policies to improve economic performance,经济模型,是更复杂的现实的简化版本 无关的细节被略去 被用来 显示经济变量之间的关系 解释经济行为 设计政策以改善经济表现,Example of a model: The supply & demand for new cars,explains the factors that determine the price of cars and the quantity sold. assumes the market is competitive: each buyer and seller is too small to affect the market price Variables: Q d = quantity of cars that buyers demand Q s = quantity that producers supply P = price of new cars Y = aggregate income Ps = price of steel (an input),模型的例子： 新车的供需模型,解释决定汽车价格和销售量的因素 假设市场是竞争性的：每个买者和卖者都太小而不能影响市场价格 变量： Q d = 买者的需求量 Q s = 生产者的供给量 P = 新车的价格 Y = 总收入 Ps = 钢铁的价格（输入）,The demand for cars,shows that the quantity of cars consumers demand is related to the price of cars and aggregate income.,对汽车的需求,消费者对汽车的需求量取决于汽车的价格和总收入。,Digression: Functional notation,General functional notation shows only that the variables are related:,参考资料: 函数符号,一般函数符号只表明变量之间是相关的：,Digression: Functional notation,General functional notation shows only that the variables are related:,A specific functional form shows the precise quantitative relationship:,参考资料: 函数符号,一般函数符号只表明变量之间是相关的：,一个具体的函数形式标明准确的定量关系：,The market for cars: demand,Q Quantity of cars,P Price of cars,The demand curve shows the relationship between quantity demanded and price, other things equal.,汽车市场：需求,Q 汽车的数量,P 汽车的价格,需求曲线表明在其他因素不变时，需求量和价格之间的关系,The market for cars: supply,汽车市场：供给,The market for cars: equilibrium,汽车市场：均衡,The effects of an increase in income:,An increase in income increases the quantity of cars consumers demand at each price,which increases the equilibrium price and quantity.,收入增加的效应：,收入的增加提高了汽车消费者在每个价格下的需求量,提高了均衡价格和数量,The effects of a steel price increase:,An increase in Ps reduces the quantity of cars producers supply at each price,which increases the market price and reduces the quantity.,钢铁价格上升的效应 ：,Ps 的上升减少了汽车生产者在每个价格下的供给量,提高了市场价格，减少了均衡数量,Endogenous vs. exogenous variables:,The values of endogenous variables are determined in the model. The values of exogenous variables are determined outside the model: the model takes their values & behavior as given. In the model of supply & demand for cars,内生变量和外生变量：,内生变量的取值在模型内被决定 外生变量的取值在模型外被决定：模型接受为给定的变量 在汽车的供求模型中，,Now you try:,Write down demand and supply equations for wireless phones; include two exogenous variables in each equation. Draw a supply-demand graph for wireless phones. Use your graph to show how a change in one of your exogenous variables affects the models endogenous variables.,现在请你尝试：,写下移动电话的需求和攻击方程 每个方程中包括两个外生变量 画出移动电话的供求图 运用图形指出某一个外生变量的变化如何影响模型的内生变量,A Multitude of Models,No one model can address all the issues we care about. For example, If we want to know how a fall in aggregate income affects new car prices, we can use the S/D model for new cars. But if we want to know why aggregate income falls, we need a different model.,模型的多样性,没有一个模型能回答所有的问题。例如： 如果我们想知道总收入如何影响新车价格，我们可使用新车的供求模型 但是，如果我们想要知道为什么总收入下降，我们需要一个不同的模型,A Multitude of Models,So we will learn different models for studying different issues (e.g. unemployment, inflation, long-run growth). For each new model, you should keep track of its assumptions, which of its variables are endogenous and which are exogenous, the questions it can help us understand, and those it cannot.,模型的多样性（续）,因此，我们将学习研究不同问题的不同模型（失业，通货膨胀，长期增长） 对于每个新模型，你应了解： 假设 哪些变量是内生的，哪些变量是外生的 它能帮助我们理解的问题 它不能帮助我们理解的问题,Prices: Flexible Versus Sticky,Market clearing: an assumption that prices are flexible and adjust to equate supply and demand. In the short run, many prices are sticky-they adjust only sluggishly in response to supply/demand imbalances. For example, labor contracts that fix the nominal wage for a year or longer magazine prices that publishers change only once every 3-4 years,价格: 伸缩性与黏性,市场出清：假设一种产品或服务的价格迅速变动以使供给量与需求量平衡。 在短期中，许多价格是黏性的它们在供求不平衡调整比较缓慢 例如： 劳动合约通常确定了长达三年的工资 杂志出版商一般只是每三年或四年改变一次自己刊物的零售价格,Prices: Flexible Versus Sticky,The economys behavior depends partly on whether prices are sticky or flexible; If prices are sticky, then demand wont always equal supply. This helps explain unemployment (excess supply of labor) the occasional inability of firms to sell what they produce Long run: prices flexible, markets clear, economy behaves very differently.,价格: 伸缩性与黏性,经济行为部分取决于价格是黏性还是伸缩性的: 如果价格是黏性的，那么需求将不会总是等于供给。这有助于解释 失业 (过量劳动供给) 企业有时不能销售完所生产的产品 长期: 价格具有伸缩性，市场出清,Microeconomic Thinking and Macroeconomic Models,Microeconomics is the study of how households and firms make decisions and how these decisionmakers interact in the marketplace. A central principle of microeconomics is that households and firms optimizethey do the best they can for themselves given their objectives and the constraints they face.,Microeconomic Thinking and Macroeconomic Models,In microeconomic models, households choose their purchases to maximize their level of satisfaction, which economists call utility, and firms make production decisions to maximize their profits.,Microeconomic Thinking and Macroeconomic Models,Because economy-wide events arise from the interaction of many households and firms, macroeconomics and microeconomics are inextricably linked. When we study the economy as a whole, we must consider the decisions of individual economic actors.,Microeconomic Thinking and Macroeconomic Models,Examples: To understand what determines total consumer spending, we must think about a family deciding how much to spend today and how much to save for the future. To understand what determines total investment spending, we must think about a firm deciding whether to build a new factory.,Microeconomic Thinking and Macroeconomic Models,Because aggregate variables are the sum of the variables describing many individual decisions, macroeconomic theory rests on a microeconomic foundation.,Microeconomic Thinking and Macroeconomic Models,Although microeconomic decisions underlie all economic models, in many models the optimizing behavior of households and firms is implicit rather than explicit. The model of the car market we discussed earlier is an example.,Microeconomic Thinking and Macroeconomic Models,Similarly, although microeconomic decisions underlie macroeconomic phenomena, macroeconomic models do not necessarily focus on the optimizing behavior of households and firms, but instead sometimes leave that behavior in the background.,Outline of this book:,Introductory material (chaps. 1 & 2) Classical Theory (chaps. 3-6) How the economy works in the long run, when prices are flexible Growth Theory (chaps. 7-8) The standard of living and its growth rate over the very long run Business Cycle Theory (chaps 9-14) How the economy works in the short run, when prices are sticky.,本书安排：,导言(chaps. 1 & 2) 古典理论(chaps. 3-6) 长期中的经济，价格具有伸缩性 增长理论(chaps. 7-8) 超长期中的生活水平及其增长率 经济周期理论(chaps 9-14) 短期中的经济，考察了当价格存在黏性时的经济行为,Outline of this book:,Policy debates (Chaps. 15-16) Shoul