高级宏观经济学ppt课件.ppt

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1、Chapter 6 Microeconomic Foundations of Incomplete Nominal Adjustment,周泳宏,introduction,The sluggish adjustment of nominal wages and prices is central to Keynesian models.Investigating the microeconomic foundations of that sluggish adjustment is necessary for making the models fully specifiedBut simpl

2、y introducing some departure from perfect markets is not enough to imply that nominal disturbances matter,Any microeconomic basis for failure of the classical dichotomy requires some kind of nominal imperfectionClassical DichotomyMonetary disturbances cause all nominal prices and wages to change,lea

3、ving the real equilibrium unchanged,We examine three nominal imperfectionsPart ALucas(1972)and Phelps(1970)The nominal imperfection is that producers do not observe the aggregate price levelPart BMonetary shocks have real effects because not all prices or wages are adjusted simultaneouslyPart CSmall

4、 costs of changing nominal prices or wagesOther small friction in nominal adjustment,Part A,The Lucas Imperfect-Information Model,Introduction,When a producer observes a change in the price of his or her product,he or she does not know whether it reflects a change in the goods relative price or a ch

5、ange in the aggregate price levelA change in the relative price alters the optimal amount to produceA change in the aggregate price level leaves optimal production unchanged,6.1 the case of perfect information,（1）Producer BehaviorRepresentative of a typical good iQi:the amount he or she producesLi:t

6、he amount that the individual worksCi:the individuals consumptionP:the price of the market basket of goods an index of the prices of all goods,The individuals consumption equals his or her real income,Utility depends positively on consumption and negatively on the amount workedP is given,The individ

7、uals labor supply and production are increasing in the relative price of his or her product,（2）DemandThe demand for a given good is assumed to depend on three factors:real income,the goods relative price,and a random disturbance to preferencesThe demand for good i is:,y:the log aggregate real income

8、z:the shock to the demand.The zis have a mean of zero across goods.:the elasticity of demand,y is assumed to equal the average across goods of the qis and P is the average of the pis,The aggregate demand side of the modelThere are various interpretations of this equationThere is an inverse relations

9、hip between the price level and outputm should be thought of as a generic variable affecting aggregate demand rather than as money,（3）EquilibriumDemand per producer equal supply,In a case of perfect information,money is neutral:an increase in m leads to an increase in p.No real variables are affecte

10、d,6.2 the case of imperfect information,Defining the relative price of good i by riThe individual does not observe ri,but must estimate it given the observation of pi,Rational expectations the producer finds the expectation of ri given pi rationally,Individuals problemProve itThe fraction of the dep

11、arture of the pi from its mean that is estimated to be due to the departure of ri from its mean is,When two variables are jointly normally distributed,the expectation of one is a linear function of the observation of the other,Lucas supply curve,Lucas supply curve the departure of output from its no

12、rmal level(which is zero)is an increasing function of the surprise in the price level,Equilibrium,The component of aggregate demand that is observed,E(m),affects only prices,but the component that is not observed,m-E(m),has real effects,Taking the expectations of both sides,The expression of b,The e

13、xpression of b,b is increasing in Vz and decreasing in VmThe special case:,6.3 Implications and Limitations,The Phillips Curve and the Lucas CritiqueLucass model implies that unexpectedly high realizations of aggregate demand lead to both higher output and higher-than-expected pricesThe model implie

14、s a positive association between output and inflation,An example,White noise,a random walk with drift,Phillips curve,However,the statistical relationship between output and inflation may change if policymakers attempt to take advantage of it,Phillips curve a positive relationship between output and

15、inflation,Lucas critique,Expectations are likely to be important to many relationships among aggregate variables,and changes in policy are likely to affect those expectationsIf policymakers attempt to take advantage of statistical relationships,effects operating through expectations may cause the re

16、lationships to break down,Anticipated and Unanticipated money,Only unobserved aggregate demand shocks have real effectsMonetary policy can stabilize output only if policymakers have information that is not available to private agentsAny portion of policy that is a response to publicly available info

17、rmationsuch as interest rates,the unemployment rate,or the index of leading indicatorsis irrelevant to the real economy,Only unobserved aggregate demand shocks have real effectslet,Empirical application:international Evidence on Output-Inflation Tradeoffs,Lucas implicationIf aggregate shocks are lar

18、ge,suppliers attribute most of the changes in the prices of their goods to changes in the price level,and so they alter their production relatively little in response to variations in prices,The estimates of the responsiveness of output to aggregate demand movements,The average size of countries agg

19、regate demand shocks:The standard deviation of the change in log nominal GDP,A measure of aggregate demand shock:the change in log nominal GDP,the real log GDP,Nominal shocks have smaller real effects in settings where aggregate demand is more volatile,Part B Staggered Price Adjustment,Introduction,

20、The next source of nominal imperfections we consider is staggered adjustment of prices and wagesThere are three reasons for the importance of the microeconomic foundationsIf not all prices or wages are free to change,aggregate demand policy can be stabilizing even under rational expectationLay the g

21、roundwork for the model where nominal rigidity is derived from optimizing behavior at the microeconomic levelIt shows that the interactions among price-setters can either magnify or dampen the effects of barriers to price adjustment,We consider three models of staggered adjustmentTime-dependent mode

22、ls Wages or prices are set by multiperiod contracts or commitmentsFischer model assumes that prices or wages are predetermined but not fixeda contract can specify a different price for each periodTaylor model assumes that the prices are fixed a contract must specify the same price each periodCaplin-

23、Spulbers State-dependent pricing modelPrices changes are triggered by developments within the economyAs a result,the fraction of prices that change in a given time interval is endogenous,Before turning to staggered adjustment,we first investigate a model of an economy of imperfectly competitive pric

24、e-setters with complete price flexibilityWe can understand the barriers of price adjustment wellIt shows that what prices firms would choose in the absence of barriers to adjustment and what happens when prices depart from those levels,6.4 A model of Imperfect Competitive and Price-Setting,Assumptio

25、nsLarge number of individualsEach one sets the price of some good and is the sole producer of that goodLabor is the only input into productionIndividuals do not produce their own goods directlyA competitive labor market where they can both sell their labor and hire workers,The shocks to the demands

26、for the individual goods(z)are absentThe utility of a typical individual isSellers with market power set price above marginal cost.Individual is profit income is,Individual is income is the sum of profit income and labor incomeCi is the individuals income divided by the price indexThe aggregate dema

27、nd side of the model,Individual Behavior,A producer with market power sets price as a markup over marginal cost,with the size of the markup determined by the elasticity of demand,Labor supply is an increasing function of the real wage,the elasticity,Equilibrium level of output,Each producers charges

28、 the same price,Implication,Symmetric allocationEquilibrium level of output,When producers have market power,they produce less than the socially optimal amount,The gap between the equilibrium and optimal levels of output is greater when producers have more market power(is lower)and when labor supply is more responsive to the real wage(is lower),Equilibrium level of price,