伯南克宏观经济学ch12

Chapter 12Unemployment and Inflation

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Chapter Outline Unemployment and Inflation: Is There a Trade-Off? The Problem of Unemployment The Problem of Inflation

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Unemployment and Inflation: Is There a Trade-off? Many people think there is a trade-off between inflation and unemployment– The idea originated in 1958 when A.W. Phillips showed a negative relationship between unemployment and nominal wage growth in Britain – Since then economists have looked at the relationship between unemployment and inflation – In the 1950s and 1960s many nations seemed to have a negative relationship between the two variables – The United States appears to be on one Phillips curve in the 1960s (Fig. 12.1)

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Figure 12.1 The Phillips curve and the U.S. economy during the 1960s

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Unemployment and Inflation: Is There a Trade-off? Many people think there is a trade-off between inflation and unemployment– This suggested that policymakers could choose the combination of unemployment and inflation they most desired – But the relationship fell apart in the following three decades (Fig. 12.2) – The 1970s were a particularly bad period, with both high inflation and high unemployment, inconsistent with the Phillips curve

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Figure 12.2 Inflation and unemployment in the United States, 1970-2005

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Unemployment and Inflation: Is There a Trade-off? The expectations-augmented Phillips curve– Friedman and Phelps: The cyclical unemployment rate (the difference between actual and natural unemployment rates) depends only on unanticipated inflation (the difference between actual and expected inflation) This theory was made before the Phillips curve began breaking down in the 1970s It suggests that the relationship between inflation and the unemployment rate isn’t stable

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Unemployment and Inflation: Is There a Trade-off? The expectations-augmented Phillips curve– How does this work in the extended classical model? First case: anticipated increase in money supply (Fig. 12.3)– AD shifts up and SRAS shifts up, with no misperceptions – Result: P rises, Y unchanged – Inflation rises with no change in unemployment

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Figure 12.3 Ongoing inflation in the extended classical model

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Unemployment and Inflation: Is There a Trade-off? The expectations-augmented Phillips curve– How does this work in the extended classical model? Second case: unanticipated increase in money supply (Fig. 12.4)– AD expected

to shift up to AD2,old (money supply expected to rise 10%), but unexpectedly money supply rises 15%, so AD shifts further up to AD2,new – SRAS shifts up based on expected 10% rise in money supply – Result: P rises and Y rises as misperceptions occur – So higher inflation occurs with lower unemployment – Long run: P rises further, Y declines to full-employment level

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Figure 12.4 Unanticipated inflation in the extended classical model

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Unemployment and Inflation: Is There a Trade-off? The expectations-augmented Phillips curve

e h(u u ) When e, u u When e, u u When e, u

(12.1)

u

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Unemployment and Inflation: Is There a Trade-off? The shifting Phillips curve– The Phillips curve shows the relationship between unemployment and inflation for a given expected rate of inflation and natural rate of unemployment – Changes in the expected rate of inflation (Fig. 12.5)

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Figure 12.5 The shifting Phillips curve: an increase in expected inflation

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Unemployment and Inflation: Is There a Trade-off? The shifting Phillips curve– Changes in the expected rate of inflation (Fig. 12.5) For a given expected rate of inflation, the Phillips curve shows the trade-off between cyclical unemployment and actual inflation The Phillips curve is drawn such that e when u u Higher expected inflation implies a higher Phillips curve

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Unemployment and Inflation: Is There a Trade-off? The shifting Phillips curve– Changes in the natural rate of unemployment (Fig. 12.6) For a given natural rate of unemployment, the Phillips curve shows the trade-off between unemployment and unanticipated inflation A higher natural rate of unemployment shifts the Phillips curve to the right

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