《经济学Chap》PPT课件.ppt

21,The Influence of Monetary and Fiscal Policy on Aggregate Demand 货币与财政政策对总需求的影响,Aggregate Demand 总需求,Many factors influence aggregate demand besides monetary and fiscal policy. 除了货币和财政政策之外，还有许多其他因素影响总需求。 In particular, desired spending by households and business firms determines the overall demand for goods and services. 特别是，家庭和企业的合意支出决定了物品与劳务的总需求。,Aggregate Demand 总需求,When desired spending changes, aggregate demand shifts, causing short-run fluctuations in output and employment. 当合意支出变动时，总需求移动，引起产量与就业的短期波动。 Monetary and fiscal policy are sometimes used to offset those shifts and stabilize the economy. 货币与财政政策有时被用来抵消这种移动，从而稳定经济。,HOW MONETARY POLICY INFLUENCES AGGREGATE DEMAND,The aggregate demand curve slopes downward for three reasons: The wealth effect The interest-rate effect The exchange-rate effect,货币政策如何影响总需求,总需求曲线由于以下三个原因而向右下方倾斜： 财富效应 利率效应 汇率效应,HOW MONETARY POLICY INFLUENCES AGGREGATE DEMAND 货币政策如何影响总需求,For the U.S. economy, the most important reason for the downward slope of the aggregate-demand curve is the interest-rate effect. 对美国经济来讲，总需求曲线向右下方倾斜的最重要原因是利率效应。,The Theory of Liquidity Preference,Keynes developed the theory of liquidity preference in order to explain what factors determine the economys interest rate. According to the theory, the interest rate adjusts to balance the supply and demand for money.,流动偏好理论,凯恩斯提出了流动偏好理论来解释决定经济中利率的因素。 根据这一理论，利率的调整使货币供给与货币需求平衡。,The Theory of Liquidity Preference,Money Supply The money supply is controlled by the Fed through: Open-market operations Changing the reserve requirements Changing the discount rate Because it is fixed by the Fed, the quantity of money supplied does not depend on the interest rate. The fixed money supply is represented by a vertical supply curve.,流动偏好理论,货币供给 货币供给由美联储通过以下方式控制: 公开市场活动 改变法定准备金 改变贴现率 由于货币供給量由美联储所固定，所以货币供給量不取决于利率。 一条垂直的供给曲线代表固定的货币供给。,The Theory of Liquidity Preference,Money Demand Money demand is determined by several factors. According to the theory of liquidity preference, one of the most important factors is the interest rate. People choose to hold money instead of other assets that offer higher rates of return because money can be used to buy goods and services. The opportunity cost of holding money is the interest that could be earned on interest-earning assets. An increase in the interest rate raises the opportunity cost of holding money. As a result, the quantity of money demanded is reduced.,流动偏好理论,货币需求 货币需求有几个因素所决定。 根据流动偏好理论，最重要的因素之一是利率。 人们选择持有货币而不持有其他提供较高收益率的资产，是因为货币可以用于购买物品与劳务。 持有货币的机会成本是本来可以在有利息的资产上赚得的利率。 利率上升增加了持有货币的机会成本。 结果是，货币需求量减少。,The Theory of Liquidity Preference,Equilibrium in the Money Market According to the theory of liquidity preference: The interest rate adjusts to balance the supply and demand for money. There is one interest rate, called the equilibrium interest rate, at which the quantity of money demanded equals the quantity of money supplied.,流动偏好理论,货币市场的均衡 根据流动偏好理论: 利率的调整使货币的供求平衡。 存在一种利率，即所谓的均衡利率，在这种利率时，货币的需求量正好与货币的供給量平衡。,The Theory of Liquidity Preference,Equilibrium in the Money Market Assume the following about the economy: The price level is stuck at some level. For any given price level, the interest rate adjusts to balance the supply and demand for money. The level of output responds to the aggregate demand for goods and services.,流动偏好理论,货币市场的均衡 假设一个经济体如下: 物价水平固定在某一水平。 给定任一物价水平，利率调整使货币供给与需求平衡。 产量水平根据对物品与劳务的总需求进行调整。,Figure 1 Equilibrium in the Money Market,Quantity of,Money,Interest,Rate,0,Quantity fixed,by the Fed,图1. 货币市场的均衡,货币量,利率,0,美联储固定的量,The Downward Slope of the Aggregate Demand Curve,The price level is one determinant of the quantity of money demanded. A higher price level increases the quantity of money demanded for any given interest rate. Higher money demand leads to a higher interest rate. The quantity of goods and services demanded falls.,总需求曲线向右下方倾斜,物价水平是货币需求量的一个决定因素。 较高的物价水平增加了任何一种既定利率时的需求量。 较高的货币需求引起了较高的利率。 物品与劳务的需求量减少了。,The Downward Slope of the Aggregate Demand Curve 总需求曲线向右下方倾斜,The end result of this analysis is a negative relationship between the price level and the quantity of goods and services demanded. 这种分析的最终结果是物价水平与物品和劳务需求量之间的负相关关系。,Figure 2 The Money Market and the Slope of the Aggregate-Demand Curve,Quantity,of Money,Quantity fixed,by the Fed,0,Interest,Rate,Money,supply,(a) The Money Market,(b) The Aggregate-Demand Curve,Quantity,of Output,0,Price,Level,Aggregate,demand,图2. 货币市场与总需求曲线的斜率,货币量,美联储固定的货币量,0,利率,货币供给,(a) 货币市场,(b) 总需求曲线,产量,0,物价 水平,总需求,Changes in the Money Supply,The Fed can shift the aggregate demand curve when it changes monetary policy. An increase in the money supply shifts the money supply curve to the right. Without a change in the money demand curve, the interest rate falls. Falling interest rates increase the quantity of goods and services demanded.,货币供给的变动,当美联储改变货币政策时，它可以使总需求曲线移动。 货币供给增加使货币供给曲线向右移动。 由于货币需求曲线未变，利率下降。 利率下降增加了物品与劳务的需求量。,Figure 3 A Monetary Injection,Aggregate,demand,A,D,Y,Quantity,of Money,0,Interest,Rate,(a) The Money Market,(b) The Aggregate-Demand Curve,Quantity,of Output,0,Price,Level,图3. 货币注入,总需求,A,D,Y,货币量,0,利率,(a) 货币市场,(b) 总需求曲线,产量,0,物价 水平,Changes in the Money Supply,When the Fed increases the money supply, it lowers the interest rate and increases the quantity of goods and services demanded at any given price level, shifting aggregate-demand to the right. When the Fed contracts the money supply, it raises the interest rate and reduces the quantity of goods and services demanded at any given price level, shifting aggregate-demand to the left.,货币供给的增加,当美联储增加了货币供给时，它降低了利率，并增加了任何一种既定物价水平时的物品与劳务需求量，使总需求曲线向右移动。 当美联储紧缩货币供给时，它提高了利率，并减少了任何一种既定物价水平时的物品与劳务需求量，使总需求曲线向左移动。,The Role of Interest-Rate Targets in Fed Policy,Monetary policy can be described either in terms of the money supply or in terms of the interest rate. Changes in monetary policy can be viewed either in terms of a changing target for the interest rate or in terms of a change in the money supply. A target for the federal funds rate affects the money market equilibrium, which influences aggregate demand.,利率目标在美联储政策中的作用,既可以根据货币供给，也可以根据利率来描述货币政策。 既可以根据利率目标的变动，也可以根据货币供给的变动来说明货币政策的变动。 联邦基金利率的目标是影响总需求的货币市场均衡。,HOW FISCAL POLICY INFLUENCES AGGREGATE DEMAND,Fiscal policy refers to the governments choices regarding the overall level of government purchases or taxes. Fiscal policy influences saving, investment, and growth in the long run. In the short run, fiscal policy primarily affects the aggregate demand.,财政政策如何影响总需求,财政政策对政府购买或税收总水平的政府选择。 财政政策影响长期中的储蓄、投资和增长。 在短期中，财政政策主要影响物品与劳务的总需求。,Changes in Government Purchases,When policymakers change the money supply or taxes, the effect on aggregate demand is indirectthrough the spending decisions of firms or households. When the government alters its own purchases of goods or services, it shifts the aggregate-demand curve directly.,政府购买的变动,当决策者改变货币供给或税收水平时，它就通过影响企业或家庭的支出决策而间接地影响总需求。 当政府改变自己购买物品与劳务量时，它就直接地使总需求移动。,Changes in Government Purchases 政府购买,There are two macroeconomic effects from the change in government purchases: 当政府购买变化时，有两种宏观经济效应： The multiplier effect 乘数效应 The crowding-out effect 挤出效应,The Multiplier Effect,Government purchases are said to have a multiplier effect on aggregate demand. Each dollar spent by the government can raise the aggregate demand for goods and services by more than a dollar.,乘数效应,政府购买对总需求有一种乘数效应。 政府支出的每一美元可以增加的物品与劳务的总需求量大于一美元。,The Multiplier Effect 乘数效应,The multiplier effect refers to the additional shifts in aggregate demand that result when expansionary fiscal policy increases income and thereby increases consumer spending. 乘数效应当扩张性财政政策增加了收入，从而增加了消费支出时引起的总需求的额外移动。,Figure 4 The Multiplier Effect,Quantity of,Output,Price,Level,0,图4. 乘数效应,产量,物价 水平,0,边际消费倾向为b，政府支出增加G ，GDP增加多少？ - Round Increase in AD Accumulative Increase in Y Car G G Food b G G+ b G Sightseeing b b G G+ b G+ b2G . N, Concert bn-1G G+ b G+ b2G +bn-1G - Y = ( 1 + b2 + b3 + + bn-1 ) G = 1/(1-b) G,A Formula for the Spending Multiplier,The formula for the multiplier is: Multiplier = 1/(1 - MPC) An important number in this formula is the marginal propensity to consume (MPC). It is the fraction of extra income that a household consumes rather than saves.,支出乘数的公式,支出乘数的公式是: 乘数= 1/(1 - MPC) 在这个公式中，一个重要的数字是边际消费倾向 (MPC)。 边际消费倾向是家庭额外收入中用于消费而不用于储蓄的比例。,A Formula for the Spending Multiplier,If the MPC is 3/4, then the multiplier will be: Multiplier = 1/(1 - 3/4) = 4 In this case, a $20 billion increase in government spending generates $80 billion of increased demand for goods and services.,支出乘数的公式,如果 MPC 是 3/4, 那么乘数是: 乘数 = 1/(1 - 3/4) = 4 在这个例子中，政府支出增加200亿美元就引起物品与劳务需求量增加800亿美元。,讨论：节俭的悖论 一个人节俭可以使一个人更富，一个国家所有的人都更节俭能不能使一个国家变富呢？,如何看待一国储蓄与消费关系？ 节俭悖论：越节俭越贫穷（越储蓄，储蓄越少） 储蓄多需求不足下一次产量减少收入减少储蓄减少。因此，节俭对个人是美德，对社会是不幸。 短期内，储蓄越少，产量越多。 长期内，储蓄越多，生产能力越大，增长越快。 如果投资充足，储蓄越多对经济越有利。,The Crowding-Out Effect,Fiscal policy may not affect the economy as strongly as predicted by the multiplier. An increase in government purchases causes the interest rate to rise. A higher interest rate reduces investment spending.,挤出效应,财政政策对经济的影响也许并不像乘数预测的那样大。 政府购买增加引起利率上升。 较高的利率减少了投资支出。,The Crowding-Out Effect,This reduction in demand that results when a fiscal expansion raises the interest rate is called the crowding-out effect. The crowding-out effect tends to dampen the effects of fiscal policy on aggregate demand.,挤出效应,挤出效应当扩张性财政政策引起利率上升，从而减少了投资支出时所引起的总需求减少。 挤出效应倾向于减弱财政政策对总需求的影响。,Figure 5 The Crowding-Out Effect,Quantity,of Money,Quantity fixed,by the Fed,0,Interest,Rate,Money demand,MD,Money,supply,(a) The Money Market,Quantity,of Output,0,Price,Level,Aggregate demand, AD1,(b) The Shift in Aggregate Demand,图5. 挤出效应,货币量,美联储固定 的货币量,0,利率,货币需求,MD,货币 供给,(a) 货币市场,货币量,0,物价 水平,总需求, AD1,(b) 总需求的移动,Copyright 2004 South-Western,The Crowding-Out Effect,When the government increases its purchases by $20 billion, the aggregate demand for goods and services could rise by more or less than $20 billion, depending on whether the multiplier effect or the crowding-out effect is larger.,挤出效应,当政府增加200亿美元的购买时，物品与劳务总需求的增加可以大于或小于200亿美元，这取决于乘数效应是大于还是小于挤出效应.,Y=Y1+Y2+Y3+Y4+.=(1+MPC+MPC2+MPC3+)=/(1-MPC),That is: Change in output=change in investment/(1-MPC) The Multiplier=1/(1-MPC)1,Changes in Taxes,When the government cuts personal income taxes, it increases households take-home pay. Households save some of this additional income. Households also spend some of it on consumer goods. Increased household spending shifts the aggregate-demand curve to the right.,税收变动,当政府减少个人所得税时，它就增加了家庭可以拿回家的工资。 家庭把一部分额外的收入储蓄起来。 家庭也把一部分收入支出于消费品。 家庭支出增加使总需求曲线向右移动。,The mechanism by which tax changes influence GDP Suppose tax rises by T, DI decreases by the same amount of T , which reduces AD by b T in the first round. T - DI = - T - AD = - b T - GDP declines - DI falls ,- Round Effect of G on AD Effect of Tax on AD 1 G - bT 2 b G - b2T 3 b 2 G - b3T . n bn-1 G - bnT - Y = ( 1 + b2 + b3 + + bn-1 ) G = 1/(1-b) G Y = ( -b - b2 - b3 - - bn ) T = (- b)( 1+b2+ b3 + + bn-1 ) T =- b/(1-b) T,The key is: G is simply part of AD and Tax not. Taxes influence C indirectly, which is part of AD. Important assumption: tax is lump-sum tax, independent of output level.,税收乘数： Y/ T = - b /（1-b） 购买支出乘数 Y/ G = 1 /（1-b） 税收乘数小于购买支出乘数 原因：购买支出直接是总需求的一部分，在第一阶段等量增加支出。税收通过影响可支配收入来影响支出，在第一阶段引起的支出变化小于税收的变化。,Changes in Taxes,The size of the shift in aggregate demand resulting from a tax change is affected by the multiplier and crowding-out effects. It is also determined by the households perceptions about the permanency of the tax change.,税收变动,税收变动引起的总需求移动的大小受乘数和挤出效应的影响。 这还取决于家庭对税收变动是持久的还是暂时的感觉，因为居民是从长久来考虑消费决策的，把一生的收入分配到不同时期的消费中，尽可能使得消费平稳。 如果是暂时的，消费增加很少。,取决于现在的减税会不会引起今后的增税 存在争论,USING POLICY TO STABILIZE THE ECONOMY 运用政策来稳定经济,Economic stabilization has been an explicit goal of U.S. policy since the Employment Act of 1946. 自从1946年的“就业法案”以来，经济稳定一直是美国政策公开的目标。,The Case for Active Stabilization Policy,The Employment Act has two implications: The government should avoid being the cause of economic fluctuations. The government should respond to changes in the private economy in order to stabilize aggregate demand.,支持积极的稳定政策,就业法案有两种含义: 政府应该避免成为经济波动的原因。 政府应该对私人经济中的变动作出反应以便稳定总需求。,The Case against Active Stabilization Policy,Some economists argue that monetary and fiscal policy destabilizes the economy. Monetary and fiscal policy affect the economy with a substantial lag. They suggest the economy should be left to deal with the short-run fluctuations on its own.,反对积极稳定政策论,一些经济学家认为，货币和财政政策反而使经济更加不稳定。 货币与财政政策对经济的影响有相对长的时滞。 他们建议让经济靠自己的力量去克服短期波动。,Automatic Stabilizers,Automatic stabilizers are changes in fiscal policy that stimulate aggregate demand when the economy goes into a recession without policymakers having to take any deliberate action. Automatic stabilizers include the tax system and some forms of government spending（Transfer payments).,自动稳定器,自动稳定器 当经济进入衰退时决策者不用采取任何有意的行动也会刺激总需求的财政政策变动。 自动稳定器包括税制和一些政府支出(转移支付)。,用TR代表转移支付，转移支付通过影响可支配收入来影响支出。 Y= bTR+ b2TR+ +bnTR+ = b（1+b+ b2+bn-1+） TR = b /（1-b） TR 转移支付乘数 Y / TR = b /（1-b） 结论：转移支付与税收的作用方向相反，程度相同,Summary,Keynes proposed the theory of liquidity preference to explain determinants of the interest rate. According to this theory, the interest rate adjusts to balance the supply and demand for money.,小结,凯恩斯提出了流动偏好理论来解释利率的决定因素。 根据这一理论，利率的调整使货币的供求平衡。,Summary,An increase in the price level raises money demand and increases the interest rate. A higher interest rate reduces investment and, thereby, the quantity of goods and services demanded. The downward-sloping aggregate-demand curve expresses this negative relationship between the price-level and the quantity demanded.,小结,物价水平增加了货币需求，并提高了利率。 较高的利率减少了投资，从而减少了物品与劳务的需求量。 向右下方倾斜的总需求曲线表现了物价水平与需求量之间的这种负相关关系。,Summary,Policymakers can influence aggregate demand with monetary policy. An increase in the money supply wi