Chap20宏观经济学曼昆.ppt

,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 production 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。,Short-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 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 Dollars,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 fluctuate 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 Short-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,Investment 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 Fluctuations,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 FLUCTUATIONS,(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 appropriate 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. 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 and 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, 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 Aggregate 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,产量,物价 水平,0,20.3.1 Why the Aggregate-Demand Curve Is Downward Sloping 为什么总需求曲线向右下方倾斜,（1）The Price Level and ConsumptionThe Wealth Effect 物价水平与消费财富效应 （2）The Price Level and InvestmentThe Interest Rate Effect 物价水平与投资利率效应 （3）The Price Level and Net ExportsThe Exchange-Rate Effect 物价水平与净出口汇率效应,（1）The Price Level and Consumption: The Wealth Effect 物价水平与消费: 财富效应 A decrease in the price level makes consumers feel more wealthy, which in turn encourages them to spend more.物价水平下降使消费者感到更富裕，这又鼓励他们更多地支出。 This increase in consumer spending means larger quantities of goods and services demanded.消费支出增加意味着物品与劳务的需求量更大了。,（2）The Price Level and Investment: The Interest Rate Effect 物价水平与投资: 利率效应 A lower price level reduces the interest rate, which encourages greater spending on investment goods.较低的物价水平降低了利率，鼓励了更多地支出用在投资物品上 This increase in investment spending means a larger quantity of goods and services demanded.这种投资支出的增加意味着物品与劳务的需求量更大了,（3）The Price Level and Net Exports: The Exchange-Rate Effect 物价水平与净出口：汇率效应 When a fall in the U.S. price level causes U.S. interest rates to fall, the real exchange rate depreciates, which stimulates U.S. net exports.当美国物价水平下降引起美国利率下降时，实际汇率贬值，而且这种贬值刺激了美国的净出口。 The increase in net export spending means a larger quantity of goods and services demanded.净出口开支的增加意味着物品与劳务的需求量更大了,20.3.2 Why the Aggregate-Demand Curve Might Shift,The downward slope of the aggregate demand curve shows that a fall in the price level raises the overall quantity of goods and services demanded. Many other factors, however, affect the quantity of goods and services demanded at any given price level. When one of these other factors changes, the aggregate demand curve shifts.,20.3.2 为什么总需求曲线会移动,总需求曲线向右下方倾斜表明物价水平下降增加了物品与劳务的总需求量。 但是，许多其他因素也影响既定物价水平时的物品与劳务的需求量。 当这些因素中的一种变动时，总需求曲线移动。,Shifts arising from 移动起因于 Consumption 消费 Investment 投资 Government Purchases 政府购买 Net Exports 净出口,Shifts in the Aggregate Demand Curve,0,P1,Y1,总需求曲线的移动,0,P1,Y1,在下列各种情形中，总需求曲线会发生什么变动？ A. 一个十年期的投资税收优惠到期 B. 美元汇率下降 C. 物价水平的下降增加了消费者财富的真实价值 D. 州政府对利息，红利和资本收益征收新税以取代销售税,课堂练习1 总需求曲线,37,A. 一个十年期的投资税收优惠到期 投资减少，总需求曲线向左移动 B. 美元汇率下降 净出口增加，总需求曲线向右移动 C. 物价水平的下降增加了消费者财富的真实价值 沿总需求曲线移动（财富效应） D. 州政府对利息，红利和资本收益征收新税以取代销售税 消费增加，总需求曲线向右移动,课堂练习 1 参考答案,38,20.4 THE AGGREGATE-SUPPLY CURVE 总供给曲线,In the long run, the aggregate-supply curve is vertical. 在长期中，总供给曲线是垂直的。 In the short run, the aggregate-supply curve is upward sloping. 在短期中，总供给曲线是向右上方倾斜的。,The Long-Run Aggregate-Supply Curve In the long run, an economys production of goods and services depends on its supplies of labor, capital, and natural resources and on the available technology used to turn these factors of production into goods and services. The price level does not affect these variables in the long run.,20.4.1 Why the Long-Run aggregate-supply curve is vertical.,长期总供给曲线 在长期中，一个经济的物品与劳务供给取决于它的资本、劳动和自然资源的供给，以及用来把资本与劳动变为物品与劳务的生产技术。 在长期中，物价水平并不影响这些变量。,20.4.1 为什么长期总供给曲线是垂直的,Figure 4 The Long-Run Aggregate-Supply Curve,Quantity of,Output,Natural rate,of output,Price,Level,0,图4. 长期总供给曲线,产量,自然产量率,物价 水平,0,The Long-Run Aggregate-Supply Curve长期总供给曲线 The long-run aggregate-supply curve is vertical at the natural rate of output.长期总供给曲线是在自然产量率时的一条垂线。 This level of production is also referred to as potential output or full-employment output.这一产量水平也被称为潜在产量或充分就业产量。,20.4.2 Why the Long-Run Aggregate-Supply Curve Might Shift 为什么长期总供给曲线会移动,Any change in the economy that alters the natural rate of output shifts the long-run aggregate-supply curve. 经济中任何改变自然产量率的变动都会使长期总供给曲线移动。 The shifts may be categorized according to the various factors in the classical model that affect output.可以根据古典模型中影响产量的各种因素把这些移动进行归类。,Shifts arising from 移动起因于 Labor 劳动 Capital 资本 Natural Resources 自然资源 Technological Knowledge 技术知识,20.4.3 A New Way to Depict Long-Run Growth and Inflation 描述长期增长与通货膨胀的新方法,Short-run fluctuations in output and price level should be viewed as deviations from the continuing long-run trends. 应该把短期产量与物价水平波动作为与持续的长期趋势的背离。,Figure 5 Long-Run Growth and Inflation,Quantity of,Output,Price,Level,0,图5. 长期增长与通货膨胀,产量,物价 水平,0,20.4.4 Why the Aggregate-Supply Curve Slopes Upward in the Short Run 为什么短期中总供给曲线向右上方倾斜,In the short run, an increase in the overall level of prices in the economy tends to raise the quantity of goods and services supplied.在短期中, 经济中物价总水平的上升倾向于增加物品与劳务的供給量。 A decrease in the level of prices tends to reduce the quantity of goods and services supplied.物价总水平的下降倾向于减少物品与劳务的供給量。,Figure 6 The Short-Run Aggregate-Supply Curve,Quantity of,Output,Price Level,0,图6. 短期总供给曲线,产量,物价 水平,0,Why the Aggregate-Supply Curve Slopes Upward in the Short Run 为什么短期中总供给曲线向右上方倾斜,The Misperceptions Theory 错觉理论 The Sticky-Wage Theory 粘性工资理论 The Sticky-Price Theory 粘性价格理论,（1）The Misperceptions Theory Changes in the overall price level temporarily mislead suppliers about what is happening in the markets in which they sell their output: A lower price level causes misperceptions about relative prices. These misperceptions induce suppliers to decrease the quantity of goods and services supplied.,（1）错觉理论 物价总水平的变动会暂时误导供给者对他们出售其产品的市场发生的变动的看法: 低物价水平引起对相对价格的错觉。 这些错觉引起供给者减少物品与劳务的供給量。,（2）The Sticky-Wage Theory Nominal wages are slow to adjust, or are “sticky” in the short run: Wages do not adjust immediately to a fall in the price level. A lower price level makes employment and production less profitable. This induces firms to reduce the quantity of goods and services supplied.,（2）粘性工资理论 名义工资调整缓慢，或者说在短期中是“粘性的”: 工资不能根据物价水平迅速调整。 较低的物价水平使就业和生产不利。 这就引起企业减少物品与劳务的供給量。,（3）The Sticky-Price Theory,Prices of some goods and services adjust sluggishly in response to changing economic conditions: An unexpected fall in the price level leaves some firms with higher-than-desired prices. This depresses sales, which induces firms to reduce the quantity of goods and services they produce.,（3）粘性价格理论,一些物品与劳务的价格对经济状况变动的调整也是缓慢的: 未预期到的物价水平下降使一些企业的价格高于合意水平。 这就抑制了销售，并引起企业减少它们生产的物品与劳务量。,20.4.5Why the Short-Run Aggregate-Supply Curve Might Shift 为什么短期总供给曲线会移动,Shifts arising from 移动起因于 Labor 劳动 Capital 资本 Natural Resources. 自然资源 Technology. 技术 Expected Price Level. 预期物价水平,An increase in the expected price level reduces the quantity of goods and services supplied and shifts the short-run aggregate supply curve to the left.预期物价水平上升减少了物品与劳务供給量，并使短期总供给曲线向左移动。 A decrease in the expected price level raises the quantity of goods and services supplied and shifts the short-run aggregate supply curve to the right.预期物价水平下降增加了物品与劳务供給量，并使短期总供给曲线向右移动。,Figure 7 The Long-Run Equilibrium,Quantity of,Output,Price,Level,0,图7. 长期均衡,产量,物价 水平,0,20.5 TWO CAUSES OF ECONOMIC FLUCTUATIONS,（1）Shifts in Aggregate Demand In the short run, shifts in aggregate demand cause fluctuations in the economys output of goods and services. In the long run, shifts in aggregate demand affect the overall price level but do not affect output.,20.5 经济波动的两个原因,（1）总需求移动 在短期中，总需求移动引起经济中物品与劳务产量的波动。 在长期中，总需求移动影响物价总水平，但不影响产量。,Figure 8 A Contraction in Aggregate Demand,Quantity of,Output,Price,Level,0,Long-run,aggregate,supply,图8. 总需求减少,产量,物价 水平,0,长期总 供给,画出美国经济的AD-SRAS-LRAS图形，从经济的长期均衡开始 加拿大出现经济繁荣，用你的图形分析这对美国 GDP，物价水平和失业率的短期与长期影响,课堂练习 2 模型的应用,68,课堂练习 2 参考答案,69,A,事件：加拿大经济繁荣 1. 影响 NX，AD曲线 2. AD曲线向右移动 3. 短期均衡在点B。P与Y 增加，失业率降低 4. 随时间的推移，PE上升，SRAS曲线一直向左移动，直到达到长期均衡点C。Y与失业率回到起始水平,0,（2）An Adverse Shift in Aggregate Supply A decrease in one of the determinants of aggregate supply shifts the curve to the left: Output falls below the natural rate of employment. Unemployment rises. The price level rises.,（2）总供给的不利移动 总供给决定因素中任何一种降低都使总供给曲线向左移动: 产量下降到自然就业率水平以下。 失业率上升。 物价水平上涨。,Figure 10 An Adverse Shift in Aggregate Supply,Quantity of,Output,Price,Level,0,Long-run,aggregate,supply,图10. 总供给的不利移动,产量,物价 水平,0,长期总供给,The Effects of a Shift in Aggregate Supply,（1）Stagflation Adverse shifts in aggregate supply cause stagflationa period of recession and inflation. Output falls and prices rise. Policymakers who can influence aggregate demand cannot offset both of these adverse effects simultaneously.,总供给移动的影响,（1）滞胀 总供给的不利移动会引起滞胀衰退和通货膨胀并存的时期。 产量减少而物价上升。 那些能影响总需求的决策者不能同时抵消这两种不利的影响。,（2）Policy Responses to Recession Policymakers may respond to a recession in one of the following ways: Do nothing and wait for prices and wages to adjust. Take action to increase aggregate demand by using monetary and fiscal policy.,总供给移动的影响,（2）对付衰退的政策 政策制定者可以用下列手段之一来对付衰退: 什么也不做，等待价格和工资调整。 利用货币和财政政策增加总需求。,Figure 11 Accommodating an Adverse Shift in Aggregate Supply,Quantity of,Output,Natural rate,of output,Price,Level,0,Long-run,aggregate,supply,Aggregate demand,AD,图11. 抵消总供给的不利移动,产量,自然产量率,物价 水平,0,长期总供给,总需求,AD,Summary,All societies experience short-run economic fluctuations around long-run trends. These fluctuations are irregular and largely unpredictable. When recessions occur, real GDP and other measures of income, spending, and production fall, and unemployment rises.,小结,所有社会都经历过围绕长期趋势的短期经济波动。 这些波动是无规律的，而且大体上是无法预测的。 当衰退发生时，实际GDP收入、支出与生产的衡量指标都下降，而失业增加。,Summary,Economists analyze short-run economic fluctuations using the aggregate demand and aggregate supply model. According to the model of aggregate