高级宏观经济学ppt课件

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,暨南大学经济学院 周泳宏,Chapter 6,Microeconomic Foundations of Incomplete Nominal Adjustment,周泳宏,tzhouyhjnu,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 specified,But simply 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 imperfection,Classical Dichotomy,Monetary disturbances cause all nominal prices and wages to change, leaving the real equilibrium unchanged,We examine three,nominal imperfections,Part A,Lucas(1972) and Phelps(1970),The nominal imperfection is that producers do not observe the aggregate price level,Part B,Monetary shocks have real effects because not all prices or wages are adjusted simultaneously,Part C,Small costs of changing nominal prices or wages,Other 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 change in the aggregate price level,A change in the relative price alters the optimal amount to produce,A change in the aggregate price level leaves optimal production unchanged,6.1 the case of perfect information,（,1,）,Producer Behavior,Representative of a typical good,i,Qi,: the amount he or she produces,Li: the amount that the individual works,Ci,: the individuals consumption,P: 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 worked,P is given,The individuals labor supply and production are increasing in the relative price of his or her product,（,2,）,Demand,The demand for a given good is assumed to depend on three factors: real income, the goods relative price, and a random disturbance to preferences,The demand for good,i,is:,y: the log aggregate real income,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 model,There are various interpretations of this equation,There is an inverse relationship between the price level and output,m should be thought of as a generic variable affecting aggregate demand rather than as money,（,3,）,Equilibrium,Demand 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 affected,6.2 the case of imperfect information,Defining the relative price of good i by r,i,The individual does not observe r,i, but must estimate it given the observation of p,i,Rational expectations,the producer finds the expectation of r,i,given p,i,rationally,Individuals problem,Prove it,The fraction of the departure of the,p,i,from its mean that is estimated to be due to the departure of,r,i,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 normal 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 expression of b,b is increasing in,V,z,and decreasing in,V,m,The special case:,6.3 Implications and Limitations,The Phillips Curve and the Lucas Critique,Lucass model implies that unexpectedly high realizations of aggregate demand lead to both higher output and higher-than-expected prices,The model implies 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 inflation,Lucas critique,Expectations are likely to be important to many relationships among aggregate variables, and changes in policy are likely to affect those expectations,If policymakers attempt to take advantage of statistical relationships, effects operating through expectations may cause the relationships to break down,Anticipated and Unanticipated money,Only unobserved aggregate demand shocks have real effects,Monetary policy can stabilize output only if policymakers have information that is not available to private agents,Any portion of policy that is a response to publicly available information,such as interest rates, the unemployment rate, or the index of leading indicators,is irrelevant to the real economy,Only unobserved aggregate demand shocks have real effects,let,Empirical application: international Evidence on Output-Inflation Tradeoffs,Lucas implication,If aggregate shocks are large, 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 aggregate 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,The next source of nominal imperfections we consider is staggered adjustment of prices and wages,There are three reasons for the importance of the microeconomic foundations,If not all prices or wages are free to change, aggregate demand policy can be stabilizing even under rational expectation,Lay the groundwork for the model where nominal rigidity is derived from optimizing behavior at the microeconomic level,It 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 adjustment,Time-dependent models,Wages or prices are set by multiperiod,contracts or commitments,Fischer model assumes that prices or wages are predetermined but not fixed,a contract can specify a different price for each period,Taylor model assumes that the prices are fixed,a contract must specify the same price each period,Caplin-Spulbers,State-dependent pricing model,Prices changes are triggered by developments within the economy,As 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 price-setters with complete price flexibility,We can understand the barriers of price adjustment well,It 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,Assumptions,Large number of individuals,Each one sets the price of some good and is the sole producer of that good,Labor is the only input into production,Individuals do not produce their own goods directly,A competitive labor market where they can both sell their labor and hire workers,The shocks to the demands for the individual goods (z) are absent,The utility of a typical individual is,Sellers with market power set price above marginal cost. Individual is,profit income is,Individual is,income is the sum of profit income and labor income,C,i,is the individuals income divided by the price index,The aggregate demand 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 the same price,Implication,Symmetric allocation,Equilibrium 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,