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1、,8 SHORT-RUN ECONOMIC FLUCTUATIONS 短期经济波动,20,Aggregate Demand and Aggregate Supply 总需求与总供给,本章我们将探索这些问题的答案：,什么是经济波动？它们的特点是什么？ 总需求与总供给模型如何解释经济波动？ 为什么总需求曲线向右下方倾斜？什么使总需求曲线移动？ 短期总供给曲线的斜率是多少？长期的呢？什么使总供给曲线移动？,3,Short-Run Economic Fluctuations,Economic activity fluctuates from year to year. In most years pr
2、oduction of goods and services rises. On average over the past 50 years, production in the U.S. economy has grown by about 3 percent per year. In some years normal growth does not occur, causing a recession.,短期经济波动,经济活动每年都有波动。 在大多数年份，物品与劳务的产量增加了。 在过去的50年间，美国经济的产量平均每年增长3%左右。 在一些年份，并没有出现这种正常增长，导致衰退。,S
3、hort-Run Economic Fluctuations 短期经济波动,A recession is a period of declining real incomes, and rising unemployment. 衰退实际GDP下降和失业增加的时期。 A depression is a severe recession. 萧条严重的衰退。,20.1 THREE KEY FACTS ABOUT ECONOMIC FLUCTUATIONS,(1)Economic fluctuations are irregular and unpredictable. Fluctuations in
4、 the economy are often called the business cycle. (2)Most macroeconomic variables fluctuate together. (3)As output falls, unemployment rises.,20.1 关于经济波动的三个事实,(1)经济波动是无规律的和无法预测的。 经济中的波动通常被称为经济周期。 (2)大多数宏观经济变量同时波动。 (3)随着产量减少，失业增加。,Figure 1 A Look At Short-Run Economic Fluctuations,Billions of,1996 Do
5、llars,Real GDP,(a) Real GDP,$10,000,9,000,8,000,7,000,6,000,5,000,4,000,3,000,2,000,1965,1970,1975,1980,1985,1990,1995,2000,图1. 观察短期经济波动,1996的 10亿美元,Real GDP,(a) 实际GDP,$10,000,9,000,8,000,7,000,6,000,5,000,4,000,3,000,2,000,1965,1970,1975,1980,1985,1990,1995,2000,Most macroeconomic variables fluctua
6、te together 大多数宏观经济变量一起波动. Most macroeconomic variables that measure some type of income or production fluctuate closely together 大多数衡量某种收入或产出的宏观经济变量同时波动. Although many macroeconomic variables fluctuate together, they fluctuate by different amounts 尽管很多宏观经济变量一起波动，但是它们波动的大小并不同.,Figure 1 A Look At Sho
7、rt-Run Economic Fluctuations,Billions of,1996 Dollars,(b) Investment Spending,$1,800,1,600,1,400,1,200,1,000,800,600,400,200,1965,1970,1975,1980,1985,1990,1995,2000,Investment spending,图1. 观察短期经济波动,(b) 投资支出,$1,800,1,600,1,400,1,200,1,000,800,600,400,200,1965,1970,1975,1980,1985,1990,1995,2000,Invest
8、ment spending,1996的 10亿美元,As output falls, unemployment rises 随着产量减少，失业增加. Changes in real GDP are inversely related to changes in the unemployment rate 实际GDP的变化与失业率的变化是反向相关的. During times of recession, unemployment rises substantially 在衰退期间，失业率大幅上升.,Figure 1 A Look At Short-Run Economic Fluctuation
9、s,Percent of,Labor Force,(c) Unemployment Rate,0,2,4,6,8,10,12,1965,1970,1975,1980,1985,1990,1995,2000,Unemployment rate,Copyright 2004 South-Western,图1. 观察短期经济波动,劳动力的 百分比,(c) 失业率,0,2,4,6,8,10,12,1965,1970,1975,1980,1985,1990,1995,2000,Unemployment rate,20.2 EXPLAINING SHORT-RUN ECONOMIC FLUCTUATION
10、S,(1)How the Short Run Differs from the Long Run Most economists believe that classical theory describes the world in the long run but not in the short run. Changes in the money supply affect nominal variables but not real variables in the long run. The assumption of monetary neutrality is not appro
11、priate when studying year-to-year changes in the economy.,20.2 解释短期经济波动,(1)长期与短期有什么不同 大多数经济学家认为，古典经济理论描述长期世界，并不描述短期世界。 在长期中，货币供给的变化影响名义变量，而不影响实际变量。 在研究逐年的经济变动时，货币中性的假设就不再适用了。,The Basic Model of Economic Fluctuations,(2)Two variables are used to develop a model to analyze the short-run fluctuations.
12、The economys output of goods and services measured by real GDP. The overall price level measured by the CPI or the GDP deflator.,经济波动的基本模型,(2)两个变量被用来建立模型分析短期经济波动。 用实际GDP衡量的经济中的物品与劳务的产量。 用CPI或GDP平减指数衡量的物价总水平。,(3)The Basic Model of Economic Fluctuations 经济波动的基本模型,The Basic Model of Aggregate Demand an
13、d Aggregate Supply 总需求与总供给基本模型 Economist use the model of aggregate demand and aggregate supply to explain short-run fluctuations in economic activity around its long-run trend. 经济学家用总需求与总供给模型来解释经济活动围绕其长期趋势的短期波动的模型。,The aggregate-demand curve shows the quantity of goods and services that households,
14、 firms, and the government want to buy at each price level. 总需求曲线一条表示在每一种物价水平时家庭、企业和政府想要购买的物品与劳务量的曲线。 The aggregate-supply curve shows the quantity of goods and services that firms choose to produce and sell at each price level. 总供给曲线一条表示在每一种物价水平下企业选择生产并销售的物品与劳务量的曲线。,Figure 2 Aggregate Demand and Ag
15、gregate Supply.,Quantity of,Output,Price,Level,0,图2. 总需求与总供给 ,产量,物价 水平,0,20.3 The Aggregate Demand Curve 总需求曲线,The four components of GDP (Y) contribute to the aggregate demand for goods and services. GDP (Y)的四个组成部分对物品与劳务的总需求做贡献。 Y = C + I + G + NX,Figure 3 The Aggregate-Demand Curve.,Quantity of,Output,Price,Level,0,图3. 总需求曲线,
