andExpectations(宏观经济学-加州大学-詹姆斯·布pja.pptx

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1、CHAPTER 12The Phillips Curve and Expectations1Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.QuestionsWhat is the Phillips curve?How has the natural rate of unemployment changed in the U.S.over the past two generations?What determines the expected rate of inflation?How can we te

2、ll how expectations of inflation are formed-whether they are static,adaptive,or rational?2Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.QuestionsHow useful is the aggregate demand-aggregate supply framework-the IS-LM model and the Phillips curve-for understanding macroeconomic

3、events in the U.S.over the past two generations?How do we connect up the sticky-price model with the flexible-price model?3Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Okuns LawOkuns law shows the relationship between the unemployment rate and real GDPor4Copyright 2002 by The

4、McGraw-Hill Companies,Inc.All rights reserved.The Three Faces of Aggregate SupplyAggregate supply relates the price level to the level of real GDPAggregate supply can also relate the inflation rate to the level of real GDPUsing Okuns law,aggregate supply can also relate the inflation rate to the une

5、mployment ratethis relationship is known as a Phillips curve5Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.The Phillips CurveAggregate supply can relate the inflation rate to the level of real GDPThe right-hand side of this equation can be substituted into Okuns Law6Copyright 2

6、002 by The McGraw-Hill Companies,Inc.All rights reserved.The Phillips CurveLetting=2.5/,we get the Phillips curveTo allow for supply shocks,we will add an extra term to the Phillips curve(s)7Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.1-The Phillips Curve8Copyright

7、2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.2-Three Faces of Aggregate Supply9Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.The Phillips CurveThe slope of the Phillips curve depends on how sticky prices and wages arethe stickier are wages and prices,the

8、smaller is parameter,and the flatter is the Phillips curveWhen the Phillips curve is flat,even large changes in the unemployment rate have little effect on the price level10Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.The Phillips CurveWhenever unemployment is equal to its nat

9、ural rate,inflation is equal to expected inflationthe position of the Phillips curve can be determined if we know the natural rate of unemployment and the expected inflation rate11Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.The Phillips CurveThe Phillips curve shifts if eithe

10、r expected inflation or the natural rate of unemployment changes or if a supply shock occursa higher natural rate moves the Phillips curve to the righthigher expected inflation moves the Phillips curve upadverse supply shocks move the Phillips curve up12Copyright 2002 by The McGraw-Hill Companies,In

11、c.All rights reserved.Figure 12.3-Shifts in the Phillips Curve13Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Aggregate DemandThe aggregate demand function developed in Chapter 11 shows how real GDP relates to the inflation rateWe can use Okuns Law to develop an aggregate deman

12、d equation with unemployment on the left-hand side14Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Aggregate DemandThe parameter is the product of three thingshow much the central bank raises the real interest rate in response to inflationhow much real GDP changes in response to

13、 a change in the real interest ratehow large a change in unemployment is produced by a change in real GDP15Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Equilibrium Levels of Inflation and UnemploymentTogether,the unemployment form of the aggregate demand relationship and the P

14、hillips curve equation allow us to determine what the inflation and unemployment rates will be in the economythe economys equilibrium is where the two curves cross16Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.4-Equilibrium Levels of Unemployment and Inflation17Copyr

15、ight 2002 by The McGraw-Hill Companies,Inc.All rights reserved.EquilibriumThe economys equilibrium inflation and unemployment rates depend onthe natural rate of unemployment(u*)the expected rate of inflation(e)supply shocks(s)the level of unemployment when the real interest rate is at what the centr

16、al bank thinks is its long-run average(u0)the central banks target level of inflation()18Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Solving for EquilibriumTo solve for the equilibrium unemployment rate,substitute the Phillips curve equation into the monetary policy reaction

17、function19Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Solving for EquilibriumTo solve for the equilibrium inflation rate,substitute the monetary policy reaction function into the Phillips curve20Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.A Decrease in

18、 ExportsIf export demand falls,and the central bank does nothing,u0 will rise by u0The effect on the equilibrium level of unemployment will beThe effect on the equilibrium level of inflation will be21Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.5-Effects of a Fall in

19、 Exports22Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.The Natural Rate of UnemploymentUnemployment cannot be reduced below its natural rate without accelerating inflationIf the natural rate of unemployment is high,expansionary fiscal and monetary policy are largely ineffectiv

20、e as tools to reduce unemploymentMost estimates of the current natural rate in the U.S.lie between 4.5 and 5.0 percent23Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.6-Fluctuations in Unemployment and the Natural Rate24Copyright 2002 by The McGraw-Hill Companies,Inc.A

21、ll rights reserved.The Natural Rate of UnemploymentFour sets of factors influence the natural rate of unemploymentdemographythe relative age and educational distribution of the labor forceinstitutionslabor unions,worker mobility,taxesproductivity growthwage growthpast levels of unemployment25Copyrig

22、ht 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.7-Real Wage Growth Aspirations and Productivity26Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Expected InflationThe natural rate of unemployment and expected inflation together determine the position of the

23、 Phillips curvehigher expected inflation moves the Phillips curve upward27Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Expected InflationThere are three basic scenarios for how inflation expectations are formedstatic expectationsprevail when people ignore the fact that inflati

24、on can changeadaptive expectationsprevail when people assume the future will be like the recent pastrational expectationsprevail when people use all the information they have as best they can28Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.The Phillips Curve under Static Expecta

25、tionsIf inflation expectations are static,expected inflation never changesthe trade-off between inflation and unemployment will not change from year to yearIf inflation has been low and stable,businesses will probably hold static inflation expectations29Copyright 2002 by The McGraw-Hill Companies,In

26、c.All rights reserved.Figure 12.9-Static Expectations of Inflation30Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Static Expectations of Inflation in the 1960sIn the 1960s,the Phillips curve did not shift up or down in response to changes in expected inflationwhen unemployment

27、was above 5.5%,inflation was below 1.5%when unemployment was below 4%,inflation was above 4%The economy moved along a stable Phillips curve31Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.10-Static Expectations and the Phillips Curve,1960-196832Copyright 2002 by The Mc

28、Graw-Hill Companies,Inc.All rights reserved.The Phillips Curve under Adaptive ExpectationsIf the inflation rate varies too much for workers and businesses to ignore it and if last years inflation rate is a good guide to inflation this year,individuals are likely to hold adaptive expectationsinflatio

29、n will be forecasted by assuming that this year will be like last yearforecast will be good only if inflation changes slowly33Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.The Phillips Curve under Adaptive ExpectationsThe Phillips curve can be writtenThe Phillips curve will shi

30、ft up and down depending on whether last years inflation was higher or lower than the previous yearsinflation accelerates when unemployment is less than the natural rate34Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Adaptive ExpectationsExamplethe government pushes the unemplo

31、yment rate down 2 percentage points below the natural rate=1/2last years inflation rate=4%This years inflation rate=4+1/22=5Next years inflation rate=5+1/22=6And so on35Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.11-Accelerating Inflation36Copyright 2002 by The McGr

32、aw-Hill Companies,Inc.All rights reserved.Adaptive Expectations and the Volcker DisinflationAt the end of the 1970s,expected inflation gave the U.S.an unfavorable short-run Phillips curve trade-offBetween 1979 and the mid-1980s,Fed chairman Paul Volcker reduced inflation from 9 to 3 percent per year

33、The fall in inflation triggered a fall in expected inflationthe Phillips curve shifted down37Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.12-The Phillips Curve before and after the Volcker Disinflation38Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reser

34、ved.The Phillips Curve under Rational ExpectationsIf the economy is changing rapidly enough that adaptive expectations lead to large errors,individuals will switch to rational expectationsPeople form their forecasts of future inflation not by looking backward but by looking forwardthey look at what

35、current and expected government policies tell us about what inflation will be39Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.The Phillips Curve under Rational ExpectationsThe Phillips curve will shift as rapidly as changes in economic policy that affect aggregate demandAnticipa

36、ted changes in economic policy turn out to have no effect on the level of production or employment40Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Government Policy to Stimulate the EconomySuppose that the unemployment rate is equal to its natural rate and inflation is equal to

37、expected inflationThe government takes steps to stimulate the economy by cutting taxes and raising government spending to reduce the unemployment rate below the natural rate41Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.13-Government Attempts to Stimulate the Economy

38、42Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Government Policy to Stimulate the EconomyIf the policy comes as a surprise,the economy moves up and to the left along the Phillips curve in response to the change in government policyUnemployment will be lower,production will be

39、higher,and the rate of inflation will be higher43Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.14-Results if the Shift in Policy Comes as a Surprise44Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Government Policy to Stimulate the EconomyIf the p

40、olicy is anticipated,individuals will take the policy into account when they form their expectations of inflationThe Phillips curve will shift upThere will be no effect on unemployment or outputThe rate of inflation will rise45Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Figur

41、e 12.15-Results if the Shift in Policy Is Anticipated46Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.What Kind of Expectations Do We Have?If inflation is low and stable,expectations are probably staticIf inflation is moderate and fluctuates slowly,expectations are probably adap

42、tiveWhen shifts in inflation are clearly related to changes in monetary policy,swift to occur,and large enough to seriously affect profitability,expectations are probably rational47Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.From the Short Runto the Long RunIn the case of an

43、anticipated shift in economic policy under rational expectations,the long run is nowIn the absence of supply shocksIf expectations are rational and changes in policy foreseen,expected inflation will be equal to actual inflation and unemployment will be at its natural rate48Copyright 2002 by The McGr

44、aw-Hill Companies,Inc.All rights reserved.Figure 12.16-Rational Expectations:The Long Run Is Now49Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.From the Short Runto the Long RunIf expectations are adaptive,the economy will approach the long run graduallyan expansionary shock wi

45、ll lower unemployment,increase real GDP,and lead to an increase in the inflation rateindividuals will raise their expectations of inflation in the next periodsas time passes,the gaps between actual unemployment and its natural rate and actual and expected inflation will shrink to zero50Copyright 200

46、2 by The McGraw-Hill Companies,Inc.All rights reserved.Figure 12.17-Adaptive Expectations Convergence to the Longer Run51Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.From the Short Runto the Long RunUnder static expectations,the long run never arrivesthe gap between expected a

47、nd actual inflation can grow arbitrarily large as different shocks hit the economyif the gap between actual and expected inflation becomes large,individuals will not remain so foolish as to retain static expectations52Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Chapter Summar

48、yThe location of the Phillips curve is determined by the expected rate of inflation and the natural rate of unemployment(and possibly by current,active supply shocks)in the absence of current,active supply shocks,the Phillips curve passes through the point at which inflation is equal to its expected

49、 value and unemployment is equal to its natural rate53Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Chapter SummaryThe slope of the Phillips curve is determined by the degree of price stickiness in the economythe more sticky are prices,the flatter is the Phillips curveThe natur

50、al rate of unemployment in the U.S.has exhibited moderate swings in the past two generations54Copyright 2002 by The McGraw-Hill Companies,Inc.All rights reserved.Chapter SummaryThree significant supply shocks have affected the rate of inflation over the past two generationsthe oil price increases of