课程经济学盛大林宏观macro lecture

1、Lecture 9 ：总供给和总需求模型提纲总需求曲线总供给曲线总供给和总需求框架负面供给冲击：滞涨货币政策财政政策治疗通货膨胀的成本短期经济波动：总供给和总需求产出波动，通货膨胀和失业率变化长期内，货币供给不会改变真实变量，只会改变名义货币中性短期内是否成立？总需求和总供给产出价格水平0总供给总需求 均衡产出均衡价格水平总需求 GDP (Y) 的四个部分构成了多商品和服务的总需求 Y = C + I + G + NX总需求产出价格水平0总需求 PYY2P22. . . . 对商品和服务的需求增加 Copyright 2004 South-Western价格水平下降为什么 价格水平和消费: 财

2、富效应价格水平和投资: 利率效应价格水平和出口: 汇率效应 为什么总需求向右下方倾斜为什么总需求向右下方倾斜价格水平和消费: 财富效应价格水平降低，使得消费者感觉更富有, 鼓励他们的消费支出更多. 消费者支出的增多，意味着对商品和服务的需求增多.为什么总需求向右下方倾斜价格水平和投资:利率效应 低的价格水平，降低利率（为什么），鼓励更多的投资 更多的投资支出意味着更多的对产品和服务的需求.为什么总需求向右下方倾斜价格水平和净出口: 汇率效应价格水平下降，导致利率降低，导致实际汇率贬值，出口增加 .出口增加，导致对商品和服务的需求增加.总需求右下方倾斜的总需求曲线，说明价格水平下降，对商品和服务

3、的需求增加.在给定的价格水平上，很多因素影响对商品和服务的需求 当这些除了价格水平之外的因素变化，总需求曲线移动.总需求曲线为什么移动总需求曲线为什么移动因为下列因素移动 消费投资政府购买净出口总需求曲线为什么移动产出价格水平0 D1P1Y1D2Y2 总供给曲线长期内，总供给曲线是垂直的.短期内是向右上方倾斜的.总供给曲线长期总供给曲线 长期内，经济的商品和服务的生产，依赖于劳动资本，自然资源和技术 在长期，价格水平不影响这些变量 总供给曲线产出潜在产出水平 价格曲线0长期总供给曲线 P2P长期总供给曲线引起移动的因素 劳动资本自然资源技术知识长期增长和通货膨胀Quantity ofOutpu

4、tY1980AD1980AD1990 AD2000PriceLevel0 LRAS1980Y1990LRAS1990Y2000LRAS2000P19801. 在长期,技术 进步 移动总供给曲线 4. . . . 持续的通货膨胀.3. . . . 导致产出的增长 . . .P1990P20002. . . . 货币供给的增长 移动总需求曲线 Copyright 2004 South-Western长期总供给曲线产出和价格水平的短期波动，应该被看作是对长期潜在趋势的偏离 长期总供给曲线在短期，价格水平上升，倾向于导致商品和服务的增加 价格水平的下降，导致商品和服务的攻击的减少 总供给曲线Quant

5、ity ofOutputPriceLevel0Short-runaggregatesupplyYPY2P2Copyright 2004 South-Western长期总供给曲线错误的感知The Misperceptions Theory粘性工资The Sticky-Wage Theory粘性价格The Sticky-Price Theory长期总供给曲线错误感知总体价格水平的变化，暂时性的引起生产者提高产出，因为生产者误以为是自己的产品价格上升 反之亦然长期总供给曲线粘性工资理论名义工资缓慢调整或者短期内不变 :价格水平下降，工资没有跟随同比下降 .那么，低得得价格水平导致企业感觉较少盈利性.

6、这使得企业减少产出和服务 长期总供给曲线商品和服务价格对经济环境调整缓慢 : 一个预期不到的价格水平下降，使得某些企业的相对价格维持在不合意的高位这将减少销售，从而减少生产 .长期总供给曲线的移动 劳动Labor资本Capital自然资源Natural Resources.技术Technology.预期的价格水平Expected Price Level.长期总供给曲线在给定的价格水平上，预期的价格水平上升，导致企业减少产品供给，供给曲线向左移动 在给定的价格水平上，预期的价格水平下降，导致企业增加产品供给，供给曲线向右移动 长期均衡潜在产出产出 PriceLevel0短期总供给曲线长期总供给曲

7、线总需求曲线A均衡价格Copyright 2004 South-Western紧缩性的总需求政策Quantity ofOutputPriceLevel0Short-run aggregatesupply, ASLong-runaggregatesupplyAggregatedemand, ADAPYAD2AS21. 总需求的减少，比如货币供给减少 . . .2. . . . 导致短期内产出的下降 . . .3. . . . 随着时间 短期总供给曲线向右移动 . . .4. . . . 产出回到长期潜在水平CP3BP2Y2Copyright 2004 South-Western短期波动的两个原因

8、总需求曲线的移动在短期内，总需求曲线的移动，导致产出的波动 .在长期内，总需求曲线的移动，不会影响产出，只会影响价格水平 .短期波动的两个原因 一个负面的总供给冲击 比如去年的暴风雪，或者口蹄疫决定总供给的某个因素的下降，使得总供给曲线向左移动 :产出下降到潜在产出水平以下 失业上升 .价格水平上升.负面的供给冲击Quantity ofOutputPriceLevel0Aggregate demand3. . . . 价格上升 2. . . . 产出下降 . . .1. 负面的短期总供给冲击使得曲线向左移动 . . .Short-runaggregatesupply, ASLong-runag

9、gregatesupplyYAPAS2BY2P2Copyright 2004 South-Western总供给曲线移动滞涨（停滞膨胀）负面冲击导致滞涨 stagflation就是衰退加通货膨胀 .产出下降，价格水平上升 政策决策者，通过管理总需求，不能同时解决衰退和通货膨胀 总供给曲线移动对衰退的政策反应比如1998年的启动总需求一般而言:什么不做，等着价格和工资自动调整 .通过货币和财政政策，增加总需求 应对负面供给冲击Quantity ofOutputNatural rateof outputPriceLevel0Short-runaggregatesupply, ASLong-runag

10、gregatesupplyAggregate demand, ADP2APAS23. . . . 这导致价格水平上升 . . .4. . . . 但是总产出维持在潜在产出水平.2. . . . 政策决策者可以通过扩张总需求来应对 . . .1. 当短期总供给下降 . . .AD2CP3Copyright 2004 South-Western总结所有的经济都面临算起经济围绕长期趋势的波动 这些波动是不规则的，大多不可预测的 当衰退发生时候，真是GDP低于潜在水平，收入，支出，生产，投资都下降，失业上升 总结总需求向右下倾斜： 财富效应，利率效应和汇率效应 任何事情和政策，只要改变消费，投资，政府

11、购买和净出口，都会移动总需求曲线 总结长期内，总供给曲线是垂直的 三个理论解释为什么短期总供给曲线向上倾斜： the misperceptions theorythe sticky-wage theorythe sticky-price theory.货币政策货币政策可以被描述为货币供给的变化或者利率的变化 .瞄准货币供给或者利率是一回事情.70年代末，美国盯住M2现在，盯住利率联邦基金利率=8.5+1.4（核心通货膨胀率-失业率）财政政策怎么影响总需求？财政政策指的是政府支出水平和税收 财政政策影响储蓄，投资和长期增长 短期内，影响总需求 政策机制当政策决策者改变货币供给或者税收，对总需求的

12、影响是间接的需要通过企业和家庭的支出决策 .小Bush减税1500亿，每人500美元当政府改变其对产品和服务的购买，这直接移动总需求曲线 1998、1999启动总需求的时候，中国政府支出改造电网，修建粮库财政政策的两个效应政府采购有两个效应 : 乘数效应挤出效应Figure 5 The Crowding-Out EffectQuantityof MoneyQuantity fixedby the Fed0InterestRaterMoney demand, MDMoneysupply(a) The Money Market3. . . . whichincreasestheequilibriu

13、minterestrate . . . 2. . . . the increase inspending increasesmoney demand . . . MD2Quantityof Output0PriceLevelAggregate demand, AD1 (b) The Shift in Aggregate Demand4. . . . which in turnpartly offsets theinitial increase inaggregate demand.AD2AD31. When an increase in government purchases increas

14、es aggregatedemand . . . r2$20 billionCopyright 2004 South-Western通货膨胀和失业，农村劳动力转移通货膨胀与失业之间存在着替代在短期内成立 Phillips 曲线 失业率0通货膨胀 Phillips curve4B67A2Copyright 2004 South-Western总供给总需求和菲利普斯曲线产出 0Short-runaggregatesupply(a) 总供给和总需求 0通货膨胀 价格水平 (b菲利普斯曲线Phillips curveLow aggregatedemandHighaggregate demand(out

15、put is8,000)B46(output is7,500)A728,000(unemployment is 4%)106B(unemploymentis 7%)7,500102ACopyright 2004 South-Western失业率1960年代菲利普斯曲线123456789100246810UnemploymentRate (percent)Inflation Rate(percent per year)19681966196119621963196719651964Copyright 2004 South-Western菲利普斯曲线失效了1970年代123456789100246

16、810UnemploymentRate (percent)Inflation Rate(percent per year)1973196619721971196119621963196719681969197019651964Copyright 2004 South-WesternThe Supply Shocks of the 1970s123456789100246810UnemploymentRate (percent)Inflation Rate(percent per year)1972197519811976197819791980197319741977Copyright 200

17、4 South-WesternThe Volcker Disinflation123456789100246810UnemploymentRate (percent)Inflation Rate(percent per year)1980198119821984198619851979A1983B1987CCopyright 2004 South-Western降低通货膨胀的成本1980年代初，通货膨胀从15%以上降到5%失业率变成10%GDP累计下降30%在中国呢？怎样估计潜在产出？潜在产出与实际产出HP FILTER(1)(2)(3)INFLATION whole sampleINFLAT

18、ION1978-1992INFLATION 1992-2007GDPGAP-0.112(0.35)laggdpgap0.9790.6413.219(3.10)*(2.89)*(3.92)*Constant0.0590.0660.048(5.80)*(6.40)*(3.66)*Observations291316R-squared0.280.430.52Absolute value of t statistics in parentheses* significant at 10%; * significant at 5%; * significant at 1% 总需求总供给我希望你已经有点收

19、获了但愿我没有很失败 单位：年利率%调整时间法定准备金超额准备金对金融机构贷款再贴现1年6个月以内3个月以内20天以内1996.05.018.828.8210.9810.1710.089*1996.08.238.287.9210.6210.179.729*1997.10.237.567.029.369.098.828.55*1998.03.215.227.927.026.846.396.031998.07.013.515.675.585.495.224.321998.12.073.245.135.044.864.593.961999.06.102.073.783.693.513.242.162

20、001.09.112.972002.02.211.893.243.152.972.702.972003.12.211.622004.03.253.873.783.63.333.242005.03.170.992008.01.014.684.594.414.144.32宏观经济学争论美联储对2001年危机的反应Classical MacroeconomicsMoney and the Price LevelClassical macroeconomics asserted that monetary policy affected only the aggregate price level,

21、not aggregate output, and that the short run was unimportant. According to the classical model, prices are flexible, making the aggregate supply curve vertical even in the short run. As a result, an increase in the money supply leads, other things equal, to an equal proportional rise in the aggregat

22、e price level, with no effect on aggregate output.As a result, increases in the money supply lead to inflation, and thats all.Classical MacroeconomicsThe Business CycleBy the 1930s, measurement of business cycles was a well- established subject, but there was no widely accepted theory of business cy

23、cles.什么时候经济周期开始?The Great Depression and the Keynesian Revolution In 1936, Keynes presented his analysis of the Great Depressionhis explanation of what was wrong with the economys alternatorin a book titled The General Theory of Employment, Interest, and Money.The school of thought that emerged out

24、of the works of John Maynard Keynes is known as Keynesian economics.Classical Versus Keynesian MacroeconomicsPolicy to Fight RecessionsThe main practical consequence of Keyness work was that it legitimized macroeconomic policy activismthe use of monetary and fiscal policy to smooth out the business

25、cycle.Fiscal Policy and the End of the Great Depression The Fisher EffectChallenges to Keynesian EconomicsThe Revival of Monetary Policy Milton FriedmanMonetarism - asserted that GDP will grow steadily if the money supply grows steadily. It called for a shift from monetary policy rule to that of a d

26、iscretionary monetary policy and argued that GDP would grow steadily if the money supply grew steadily; monetarism was influential for a time but was eventually rejected by many macroeconomists.Fiscal Policy with a Fixed Money SupplyMonetarismWhen the central bank changes interest rates or the money

27、 supply based on its assessment of the state of the economy, it is engaged in discretionary monetary policy.A monetary policy rule is a formula that determines the central banks actions.Recalling the velocity equation: M V = P Y Monetarists believed that V was stable, so they believed that if the Fe

28、deral Reserve kept M on a steady growth path, nominal GDP would also grow steadily.The Velocity of MoneyInflation and the Natural Rate of UnemploymentThe natural rate of unemployment is also the non-accelerating-inflation rate of unemployment, or NAIRU. According to the hypothesis of the NAIRU, infl

29、ation eventually gets built into expectations, so any attempt to keep the unemployment rate below the natural rate will lead to an ever-rising inflation rate.The natural rate hypothesis became almost universally accepted, limiting the role of macroeconomic policy to stabilizing the economy, not seek

30、ing a permanently lower unemployment rate.The Political Business CycleA political business cycle results when politicians use macroeconomic policy to serve political ends.Fears of a political business cycle led to a consensus that monetary policy should be insulated from politics.Rational Expectations, Real Business Cycles, andNew Classical MacroeconomicsNew classical macroeconomics is an approach to the business cycle that returns to the classical view that shifts in the aggregate demand curve affect only the aggregate price level, not the aggregate output.Rational ExpectationsRat