北大经院：Chapter33总供给与总需求20160515课件.pptx

1、1第三十三章第三十三章总需求与总供给总需求与总供给Aggregate Demand and Aggregate Supply2But This“Long Run”is a misleading guide to current affaires.“In the long run”we are all dead.Economists set themselves too easy,too useless a task if in tempestuous seasons they can only tell us that when the storm is long past the ocean

2、 is flat again._John Maynard KeynesLong run and short runLong-run model potential output,long-run inflationShort-run model current output,current inflation Actual output=long-run trend+short-run fluctuation The short run is defined to be the length of time over which these deviations occur.3总需求与总供给总

3、需求与总供给Aggregate Demand and Aggregate Supplyuthree key facts about short-run economic fluctuations.u how the economy in the short run differs from the economy in the long run.u how to use the model of aggregate demand and aggregate supply to explain economic fluctuations.u how shifts in either aggreg

4、ate demand or aggregate supply can cause booms and recessions.45短期经济波动短期经济波动Short-Run Economic Fluctuationsu经济活动年复一年地波动经济活动年复一年地波动 Economic activity fluctuates from year to year.u在大多数年份里，物品与服务的生产是上升的在大多数年份里，物品与服务的生产是上升的 In most years production of goods and services rises.u在过去在过去50年，平均来说，美国经济的生产每年增长

5、年，平均来说，美国经济的生产每年增长约约3个百分点。个百分点。On average over the past 50 years,production in the U.S.economy has grown by about 3 percent per year.u在一些年份，正常的增长没能出现，导致了衰退。在一些年份，正常的增长没能出现，导致了衰退。In some years normal growth does not occur,causing a recession.6短期经济波动短期经济波动Short-Run Economic Fluctuationsu衰退衰退是实际是实际GDP下

6、降、收入减少、失业上下降、收入减少、失业上升的时期升的时期 A recession is a period of declining real GDP,falling incomes,and rising unemployment.u萧条萧条是严重的衰退是严重的衰退 A depression is a severe recession.7衰退衰退Recessions(a)Real GDP 实际实际GDP:Figure31-1Billions of1992 Dollars19651970197519801985199019952,5003,0003,5004,0004,5005,0005,500

7、6,0006,500$7,000Real GDP短期经济波动一瞥短期经济波动一瞥 A Look At Short-Run Economic Fluctuations8Recessions(b)Investment Spending投资支出投资支出Billions of1992 Dollars3004005006007008009001,000$1,100Investment spending1965197019751980198519901995短期经济波动一瞥短期经济波动一瞥 A Look At Short-Run Economic Fluctuations9Recessions(c)Une

8、mployment Rate失业率失业率Unemployment rate0246810121965197019751980198519901995Percent ofLabor Force短期经济波动一瞥短期经济波动一瞥 A Look At Short-Run Economic Fluctuations10衰退0 050050010001000150015002000200025002500300030003500350040004000450045001952195219571957196219621967196719721972197719771982198219871987199219

9、921997199720022002年年 份份指数（1952=100）指数（1952=100）短期经济波动一瞥：中国短期经济波动一瞥：中国 A Look At Short-Run Economic Fluctuations:China(a)实际实际GDP资料来源：中国国内生产总值核算历史资料，19521995，中国统计年鉴以及作者计算。11衰退0 01000100020002000300030004000400050005000600060007000700080008000900090001952195219571957196219621967196719721972197719771982

10、198219871987199219921997199720022002年年 份份指数（1952=100）指数（1952=100）短期经济波动一瞥：中国短期经济波动一瞥：中国 A Look At Short-Run Economic Fluctuations:China(b)投资支出投资支出12中国：中国：GDP、工业生产总值、固定资产投资年增工业生产总值、固定资产投资年增长率的波动长率的波动-20.00%-10.00%0.00%10.00%20.00%30.00%40.00%50.00%60.00%70.00%19781979198019811982198319841985198619871

11、9881989199019911992199319941995199619971998199920002001200220032004200520062007固定资产投资增长率工业总产值增长率GDP年增长率13关于经济波动的三个关键事实关于经济波动的三个关键事实Three Key Facts About Economic Fluctuationsu经济波动是不规则和不可预测的。经济波动是不规则和不可预测的。Economic fluctuations are irregular and unpredictable.u经济当中的波动常常被称作经济当中的波动常常被称作经济周期经济周期（或译（或译商商

12、业周期业周期）Fluctuations in the economy are often called the business cycle.uTrash indicator(The Chicago Tribune)14关于经济波动的三个关键事实关于经济波动的三个关键事实Three Key Facts About Economic Fluctuationsu大多数宏观经济变量一起波动。大多数宏观经济变量一起波动。Most macroeconomic variables fluctuate together.u大多数衡量某种收入或生产的宏观经济变量几乎大多数衡量某种收入或生产的宏观经济变量几乎同

13、时波动。同时波动。Most macroeconomic variables that measure some type of income or production fluctuate closely together.u虽然许多宏观经济变量一起波动，他们波动的幅虽然许多宏观经济变量一起波动，他们波动的幅度并不同。度并不同。Although many macroeconomic variables fluctuate together,they fluctuate by different amounts.15关于经济波动的三个关键事实关于经济波动的三个关键事实Three Key Fact

14、s About Economic Fluctuationsu随着产出下降，失业上升。随着产出下降，失业上升。As output falls,unemployment rises.u实际实际GDP的变化和失业率的变化呈反向关系。的变化和失业率的变化呈反向关系。Changes in real GDP are inversely related to changes in the unemployment rate.u在衰退时期，失业大幅上升。在衰退时期，失业大幅上升。During times of recession,unemployment rises substantially.16短期与长期

15、有何不同短期与长期有何不同How the Short Run Differs From the Long Runu大多数经济学家相信，古典理论描述了长期而大多数经济学家相信，古典理论描述了长期而不是短期中的世界。不是短期中的世界。Most economists believe that classical theory describes the world in the long run but not in the short run.u货币供给的变化影响长期中的名义变量而非实际变量货币供给的变化影响长期中的名义变量而非实际变量 Changes in the money supply af

16、fect nominal variables but not real variables in the long run.u货币货币中性（二分法）的中性（二分法）的假设在研究经济的逐年变化时假设在研究经济的逐年变化时是不恰当的是不恰当的 The assumption of monetary neutrality is not appropriate when studying year-to-year changes in the economy.17经济波动的基本模型经济波动的基本模型The Basic Model of Economic Fluctuationsu我们用两个变量来建立一个

17、模型，以分析短期我们用两个变量来建立一个模型，以分析短期波动。波动。Two variables are used to develop a model to analyze the short-run fluctuations.u以实际以实际GDP衡量的经济当中物品与服务的产出。衡量的经济当中物品与服务的产出。The economys output of goods and services measured by real GDP.u以以CPI或或GDP平减指数衡量的整体价格水平。平减指数衡量的整体价格水平。The overall price level measured by the CP

18、I or the GDP deflator.18经济波动的基本模型经济波动的基本模型The Basic Model of Economic Fluctuations经济学家使用经济学家使用总需求总需求与与总供给总供给模型来解模型来解释经济活动围绕其长期趋势的短期波动释经济活动围绕其长期趋势的短期波动Economist use the model of aggregate demand and aggregate supply to explain short-run fluctuations in economic activity around its long-run trend.19经济

19、波动的基本模型经济波动的基本模型The Basic Model of Economic Fluctuationsu总需求曲线总需求曲线表示家庭、企业或政府在任一价表示家庭、企业或政府在任一价格水平上想要购买的物品与服务的数量。格水平上想要购买的物品与服务的数量。The aggregate demand curve shows the quantity of goods and services that households,firms,and the government want to buy at each price level.20经济波动的基本模型经济波动的基本模型The Basi

20、c Model of Economic Fluctuationsu总供给曲线总供给曲线表示企业在任一价格水平上生表示企业在任一价格水平上生产和销售的物品与服务的数量。产和销售的物品与服务的数量。The aggregate supply curve shows the quantity of goods and services that firms produce and sell at each price level.21总需求与总供给总需求与总供给Aggregate Demand and Aggregate Supply.EquilibriumOutput均衡产出均衡产出Quantity

21、 ofOutput产出数量产出数量PriceLevel价格水平价格水平0Equilibriumprice level均衡价格水平均衡价格水平AggregateSupply总供给总供给AggregateDemand总需求总需求22总需求曲线总需求曲线The Aggregate Demand CurveuGDP（Y）的四个组成部分构成了对物品与的四个组成部分构成了对物品与服务的总需求。服务的总需求。The four components of GDP(Y)contribute to the aggregate demand for goods and services.Y=C+I+G+NX23总需

22、求曲线总需求曲线The Aggregate-Demand Curve.Quantity ofOutputPriceLevel0AggregatedemandP1Y1Y2P22.增加了物品与服务的需求数量增加了物品与服务的需求数量increases the quantity of goods and services demanded.1.价格水平价格水平的下降的下降 A decrease in the price level.24为什么总需求曲线向下倾斜为什么总需求曲线向下倾斜Why the Aggregate Demand Curve Is Downward Slopingu价格水平与消费：

23、财富效应价格水平与消费：财富效应 The Price Level and Consumption:The Wealth Effectu价格水平与投资：利率效应价格水平与投资：利率效应 The Price Level and Investment:The Interest Rate Effectu价格水平与净出口：汇率效应价格水平与净出口：汇率效应 The Price Level and Net Exports:The Exchange-Rate Effect25价格水平与消费：财富效应价格水平与消费：财富效应The Price Level and Consumption:The Wealth

24、Effectu价格水平的下降使得消费者感觉更加富有，这价格水平的下降使得消费者感觉更加富有，这反过来鼓励他们支出更多。反过来鼓励他们支出更多。A decrease in the price level makes consumers feel more wealthy,which in turn encourages them to spend more.u消费支出的上升意味着对物品与服务更大的需消费支出的上升意味着对物品与服务更大的需求数量。求数量。This increase in consumer spending means larger quantities of goods and

25、services demanded.26价格水平与投资：利率效应价格水平与投资：利率效应The Price Level and Investment:The Interest Rate Effectu更低的价格更低的价格水平水平增加增加了储蓄，了储蓄，降低降低了利率，了利率，这鼓励了对投资品的更大支出。这鼓励了对投资品的更大支出。A lower price level reduces the interest rate,which encourages greater spending on investment goods.u投资支出的增加意味着物品与服务的需求数投资支出的增加意味着物品与服

26、务的需求数量更大。量更大。This increase in investment spending means a larger quantity of goods and services demanded.27价格水平与净出口：汇率效应价格水平与净出口：汇率效应The Price Level and net Exports:The Exchange-Rate Effectu当美国的价格水平下降导致了美国的利率下当美国的价格水平下降导致了美国的利率下降，实际汇率就会贬值，这又刺激了美国的降，实际汇率就会贬值，这又刺激了美国的净出口。净出口。When a fall in the U.S.pri

27、ce level causes U.S.interest rates to fall,the real exchange rate depreciates,which stimulates U.S.net exports.u净出口支出的增加意味着物品与服务的需求净出口支出的增加意味着物品与服务的需求数量更大。数量更大。The increase in net export spending means a larger quantity of goods and services demanded.28总需求曲线为什么会移动总需求曲线为什么会移动Why the Aggregate Demand

28、Curve Might Shiftu总需求曲线向下倾斜，表示价格水平的下降增加了物品与总需求曲线向下倾斜，表示价格水平的下降增加了物品与服务总的需求数量。服务总的需求数量。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.u然而，在给定价格水平上，许多其他因素影响物品与服务然而，在给定价格水平上，许多其他因素影响物品与服务的需求数量。的需求数量。Many o

29、ther factors,however,affect the quantity of goods and services demanded at any given price level.u当这些其他因素中的任一种发生改变，总需求曲线移动。当这些其他因素中的任一种发生改变，总需求曲线移动。When one of these other factors changes,the aggregate demand curve shifts.29总需求曲线为什么会移动总需求曲线为什么会移动Why the Aggregate Demand Curve Might Shiftu来自消费的移动来自消费

30、的移动 Shifts arising from Consumptionu来自投资的移动来自投资的移动 Shifts arising from Investmentu来自政府购买的移动来自政府购买的移动 Shifts arising from Government Purchasesu来自净出口的移动来自净出口的移动 Shifts arising from Net Exports30总需求曲线的移动总需求曲线的移动Shifts in the Aggregate Demand Curve.Quantity ofOutputPriceLevel0Aggregatedemand,D1P1Y1D2Y2

31、31总供给曲线总供给曲线The Aggregate Supply Curveu在在长期长期中，总供给曲线是中，总供给曲线是垂直垂直的的。In the long run,the aggregate-supply curve is vertical.u在在短期短期内，总供给曲线内，总供给曲线向上倾斜向上倾斜。In the short run,the aggregate-supply curve is upward sloping.32长期总供给曲线长期总供给曲线The Long-Run Aggregate Supply Curveu在长期中，经济的物品与服务的生产依赖于它的在长期中，经济的物品与服

32、务的生产依赖于它的劳动、资本与自然资源的供给，以及将这些生产劳动、资本与自然资源的供给，以及将这些生产要素转化为产品与服务的可行技术。要素转化为产品与服务的可行技术。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 servi

33、ces.u价格水平在长期中不影响这些变量。价格水平在长期中不影响这些变量。The price level does not affect these variables in the long run.33长期总供给曲线长期总供给曲线The Long-Run Aggregate-Supply Curve.Quantity ofOutputNatural rateof outputPrice Level0Long-runaggregatesupplyP1P2 2.不影响长期中物品与不影响长期中物品与服务的供给数量服务的供给数量 does not affect the quantity of go

34、ods and services supplied in the long run.1.价格水平的改变价格水平的改变 A change in the price level34长期总供给曲线长期总供给曲线The Long-Run Aggregate Supply Curveu长期总供给曲线垂直于长期总供给曲线垂直于自然产出率自然产出率处。处。The long-run aggregate supply curve is vertical at the natural rate of output.u这一生产水平也被称为这一生产水平也被称为潜在产出潜在产出或或充分充分就业产出。就业产出。This

35、level of production is also referred to as potential output or full-employment output.35长期总供给曲线为什么会移动长期总供给曲线为什么会移动Why the Long-Run Aggregate Supply Curve Might Shiftu任何改变自然产出率的经济变化都会移动长期任何改变自然产出率的经济变化都会移动长期总供给曲线。总供给曲线。Any change in the economy that alters the natural rate of output shifts the long-r

36、un aggregate-supply curve.u这样的移动可以按照古典模型中影响产出的若这样的移动可以按照古典模型中影响产出的若干因素来分类。干因素来分类。The shifts may be categorized according to the various factors in the classical model that affect output.36长期总供给曲线为什么移动长期总供给曲线为什么移动Why the Long-Run Aggregate Supply Curve Might Shiftu来自劳动的移动来自劳动的移动 Shifts arising from L

37、aboru来自资本的移动来自资本的移动 Shifts arising from Capitalu来自自然资源的移动来自自然资源的移动 Shifts arising from Natural Resourcesu来自技术知识的移动来自技术知识的移动 Shifts arising from Technological Knowledge371.在长期中，技术进步移动长期总供给 In the long-run,technological progress shifts long-run aggregate supply.LRAS2000LRAS1990长期增长与通货膨胀长期增长与通货膨胀 Long-

38、Run Growth and Inflation.Quantity ofOutputPrice Level0P1980Y1980AD1980P2000P1990LRAS19802.货币供给的增长移动总需求 and growth in the money supply shifts aggregate-demand.AD2000AD19904.和持续的通货膨胀 and ongoing inflation.Y1990Y20003.导致产出增长leading to growth in output.38长期增长与通货膨胀长期增长与通货膨胀Long-Run Growth and Inflation短期

39、的产出与价格波动应该被看成是短期的产出与价格波动应该被看成是对持续的长期趋势的偏离。对持续的长期趋势的偏离。Short-run fluctuations in output and price level should be viewed as deviations from the continuing long-run trends.39短期总供给曲线为什么向上倾斜短期总供给曲线为什么向上倾斜Why the Short-Run Aggregate Supply Curve Slopes Upward in the Short Runu在短期内，经济中整体价格水平的上升倾向于在短期内，经济中

40、整体价格水平的上升倾向于增加物品与服务的供给数量。增加物品与服务的供给数量。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.u价格水平的下降倾向于减少物品与服务的供给价格水平的下降倾向于减少物品与服务的供给数量。数量。A decrease in the level of prices tends to reduce the quantity of goods and servi

41、ces supplied.40短期总供给曲线短期总供给曲线The Short-Run Aggregate Supply Curve.Quantity ofOutputPrice Level0Short-runaggregatesupplyY1P1Y22.减少了短期内物品与服务的供给数量 reduces the quantity of goods and services supplied in the short run.P21.价格水平的下降 A decrease in the price level41短期总供给曲线为什么向上倾斜短期总供给曲线为什么向上倾斜Why the Short-Ru

42、n Aggregate Supply Curve Slopes Upward in the Short Runu错觉理论错觉理论 The Misperceptions Theoryu粘性工资理论粘性工资理论 The Sticky-Wage Theoryu粘性价格理论粘性价格理论 The Sticky-Price Theory42错觉理论错觉理论The Misperceptions Theoryu总体价格水平的改变，暂时性地误导供给者，让他总体价格水平的改变，暂时性地误导供给者，让他们在出售自己产出的市场上，看不清正在发生什么们在出售自己产出的市场上，看不清正在发生什么 Changes in t

43、he overall price level temporarily mislead suppliers about what is happening in the markets in which they sell their output:u更低的价格水平导致了对相对价格的错觉。更低的价格水平导致了对相对价格的错觉。A lower price level causes misperceptions about relative prices.u这种错觉使得供给者减少物品与服务的供给数量。这种错觉使得供给者减少物品与服务的供给数量。These misperceptions induce

44、suppliers to decrease the quantity of goods and services supplied.43粘性工资理论粘性工资理论The Sticky-Wage Theoryu名义工资的调整是缓慢的，或者说，在短期内是名义工资的调整是缓慢的，或者说，在短期内是 “粘性的粘性的”。Nominal wages are slow to adjust,or are“sticky”in the short run:u工资并不随着价格水平的下降而立即调整。工资并不随着价格水平的下降而立即调整。Wages do not adjust immediately to a fall

45、in the price level.u更低的价格水平使得雇佣和生产的利润更低。更低的价格水平使得雇佣和生产的利润更低。A lower price level makes employment and production less profitable.u这就导致企业减少物品与服务的供给数量。这就导致企业减少物品与服务的供给数量。This induces firms to reduce the quantity of goods and services supplied.44粘性价格理论粘性价格理论The Sticky-Price Theoryu某些物品与服务的价格为适应经济状况变化所进行

46、某些物品与服务的价格为适应经济状况变化所进行的调整是迟缓的。的调整是迟缓的。Prices of some goods and services adjust sluggishly in response to changing economic conditions:u价格水平的未预料到的下降，留下某些企业的价格超价格水平的未预料到的下降，留下某些企业的价格超过了合意的水平。过了合意的水平。An unexpected fall in the price level leaves some firms with higher-than-desired prices.u这会压低销售，引起企业减少物

47、品与服务的生产数量这会压低销售，引起企业减少物品与服务的生产数量This depresses sales,which induces firms to reduce the quantity of goods and services they produce.45短期总供给曲线为什么向上倾斜短期总供给曲线为什么向上倾斜Why the Short-Run Aggregate Supply Curve Slopes Upward in the Short Runu所有这三个理论都表明，当实际价格水平背离人们预所有这三个理论都表明，当实际价格水平背离人们预期的（期的（expected）价格水平时，

48、产量就背离其自然率价格水平时，产量就背离其自然率。u用数学公式表述如下：用数学公式表述如下：产品供给量产品供给量 自然产量率自然产量率a(实际价格水平预期价格水平）实际价格水平预期价格水平）u短期中，预期价格水平难以调整，实际价格水平的上短期中，预期价格水平难以调整，实际价格水平的上升增加了产品供给量，总供给曲线向上倾斜。升增加了产品供给量，总供给曲线向上倾斜。u长期中，预期价格水平得到调整，以致与实际价格水长期中，预期价格水平得到调整，以致与实际价格水平相等，总供给曲线垂直于自然产量率处。平相等，总供给曲线垂直于自然产量率处。46短期总供给曲线为什么向上倾斜短期总供给曲线为什么向上倾斜Why

49、 the Short-Run Aggregate Supply Curve Slopes Upward in the Short Run在短期内，在短期内，实际价格下实际价格下降降而预期价格而预期价格不变不变结果是结果是错觉理论错觉理论供给者自供给者自己的产品价格己的产品价格下降下降供给者认供给者认为其他产品价为其他产品价格不变格不变供给者误认为供给者误认为自己产品的相自己产品的相对价格下降，对价格下降，从而减少产出从而减少产出粘性工资理论粘性工资理论供给者自供给者自己的产品价格己的产品价格下降下降供给者不供给者不能调整名义工能调整名义工资资供给者由于产供给者由于产品价格下降而品价格下降而减少

50、产出减少产出粘性价格理论粘性价格理论其他供给其他供给者的价格下降者的价格下降供给者自供给者自己产品的价格己产品的价格无法调整无法调整供给者自己产供给者自己产品的相对价格品的相对价格上升，需求下上升，需求下降，从而减少降，从而减少产出。产出。47总供给曲线为什么会移动总供给曲线为什么会移动Why the Aggregate Supply Curve Might Shiftu来自劳动力的移动来自劳动力的移动 Shifts arising from Laboru来自资本的移动来自资本的移动 Shifts arising from Capitalu来自自然资源的移动来自自然资源的移动 Shifts a