自然失业率（natural rate of unemployment)

什么因素决定自然失业率？

What determines the natural rate of unemployment？

解释衰退会提高自然失业率的两种方式。

Explain two ways in which a recession might raise the natural rate of unemployment.

经济学家如何解释20世界70年代和80年代的高自然失业率？他们如何解释20世界90年代自然失业率的下降？

How do economists explain the high natural rate of unemployment in the 1970s and 1980s？ How do they explain the fall in the natural rate in the 1990s？

率？ What would happen if the government tries to lower the natural rate of unemployment through macroeconomic policies？What types of measures would you recommend to reduce effectively the natural rate of unemployment？

说明了稳定状态失业率是U/L=s/(s+f)。假设失业率开始时并不在这个水平。说明失业率将一直变动并达到这种稳定状态。(提示：把失业人数变动作为s，f和U的函数。然后说明，如果失业高于自然失业率，失业下降；如果失业低于自然失业率，失业增加。)

In this chapter we saw that the steady-state rate of unemployment is U/L=s/(s+f). Suppose that the unemployment rate does not begin at this level. Show that unemployment will evolve over time and reach this steady state. (Hint: Express the change in the number of unemployed as a function of s,f, and U. Then show that if unemployment is above the natural rate, unemployment falls, and if unemployment is below the natural rate, unemployment rises.)

a．把人均产出(y=Y/L)表示为人均资本(k=K/L)和自然失业率的函数。描述该经济的稳定状态。

b．假定政府政策的某些变化降低了自然失业率。描述这一变化随时间的推进如何影响产出。对产出的稳定状态的影响大于还是小于立即的影响？请解释。

Consider how unemployment would affect the Solow growth model. Suppose that output is produced according to the production function Y=K^α[(1-u^*)L]^1-α，where K is capital, L is the labor force, and u^*is the natural rate of unemployment. The national saving rate is s, the labor force grows at rate n, and capital depreciates at rate δ.

a．Express output per worker (y=Y/L) as a function of capital per worker (k=K/L) and the natural rate of unemployment. Describe the steady state of this economy.

b．Suppose that some change in government policy reduces the natural rate of unemployment. Describe how this change affects output both immediately and over time. Is the steady-state effect on output larger or smaller than the immediate effect？ Explain.

政策是斟酌处置的。

a．在到现在为止所建立的模型中，当自然失业率上升时，通货膨胀率会发生什么变动？

b．现在通过假设美联储的损失函数中通货膨胀和失业都是二次的来略微改变模型，即：L(u，π)=u²+γπ²。按照与正文中相似的步骤解出斟酌处置政策下的通货膨胀率。

c．当自然失业率上升时，通货膨胀率会发生什么变动？

d．在1979年。吉米·卡特总统任命了保守派的中央银行家保罗·沃尔克出掌美联储。根据这个模型，通货膨胀和失业会发生什么变动？

In the 1970s in the United States, the inflation rate and the natural rate of unemployment both rose. Let's use this model of time inconsistency to examine this phenomenon. Assume that policy is discretionary.

a．In the model as developed so far, what happens to the inflation rate when the natural rate of unemployment rises？

b．Let's now change the model slightly by supposing that the Fed's loss function is quadratic in both inflation and unemployment. That is, L(u，π)=u²+γπ². Follow steps similar to those in the text to solve for the inflation rate under discretionary policy.

c．Now what happens to the inflation rate when the natural rate of unemployment rises？

d．In 1979, President Jimmy Carter appointed the conservative central banker Paul Volcker to head the Federal Reserve. According to this model, what should have happened to inflation and unemployment？

考虑失业会如何影响索洛增长模型。假定产出是根据生产函数Y=K^a[(1-u＜sup＞*＜/sup＞)L]^1-a而生产的。式中，K为资本；L为劳动；u^*为自然失业率。国民储蓄率为s，劳动力增长率为n。资本折旧率为δ。

a．把人均产出(y=Y/L)表示为人均资本(k=K/L)和自然失业率的函数。描述该经济的稳定状态。

b．假定政府政策的某些变化降低了自然失业率。描述这一变化随时间的推进如何影响产出。对产出的稳定状态的影响大于还是小于立即的影响？请解释。

Consider how unemployment would affect the Solow growth model. Suppose that output is produced according to the production function Y=K^α[(1-u＜sup＞*＜/sup＞)L]^1-α，where K is capital, L is the labor force, and u^*is the natural rate of unemployment. The national saving rate is s, the labor force grows at rate n, and capital depreciates at rate δ.

a．Express output per worker (y=Y/L) as a function of capital per worker (k=K/L) and the natural rate of unemployment. Describe the steady state of this economy.

b．Suppose that some change in government policy reduces the natural rate of unemployment. Describe how this change affects output both immediately and over time. Is the steady-state effect on output larger or smaller than the immediate effect？ Explain.

假设国会通过了使企业更难解雇工人的立法(一个例子是法律要求企业向被解雇的工人支付离职金)。如果这项法律不影响就业率而降低了离职率，自然失业率会如何变动？你认为这项立法不影响就业率有道理吗？为什么有或为什么没有？

Suppose that Congress passes legislation making it more difficult for firms to fire workers. (An example is a law requiring severance pay for fired workers.) If this legislation reduces the rate of job separation without affecting the rate of job finding, how would the natural rate of unemployment change？ Do you think that it is plausible that the legislation would not affect the rate of job finding？ Why or why not？