假定经济的菲利普斯曲线是：π=π－1－0.5（u－un)，而且自然失业率是由过去两年失业的平均数给出的：un=0.5（u－1＋u－2

假定经济的菲利普斯曲线是：π=π_-1-0.5(u-uⁿ)，而且自然失业率是由过去两年失业的平均数给出的：uⁿ=0.5(u_-1+u_-2)。

  a．为什么自然失业率会取决于最近的失业(正如在上式中所假设的)？

  b．假设美联储遵循永久性地降低通货膨胀1%的政策。这种政策对一段时期中的失业率有什么影响？

  c．这个经济中的牺牲率是多少？请解释。

  d．这些方程式对通货膨胀与失业之间的短期和长期取舍关系意味着什么？

  Suppose that an economy has the Phillips curve π=π_-1-0.5(u-uⁿ), and that the natural rate of unemployment is given by an average of the past two years'unemployment: uⁿ=0.5(u_-1+u_-2).

  a．Why might the natural rate of unemployment depend on recent unemployment (as is assumed in the preceding equation)？

  b．Suppose that the Fed follows a policy to reduce permanently the inflation rate by 1 percentage point. What effect that policy will have on the unemployment rate over time？

  c．What is the sacrifice ratio in this economy？ Explain.

  d．What do these equations imply about the short-run and long-run tradeoffs between inflation and unemployment？