宏观经济学ch06.ppt

Chapter objectives The natural rate of unemployment: what it means what causes it understanding its behavior in the real world Natural Rate of Unemployment Natural rate of unemployment: the average rate of unemployment around which the economy fluctuates. In a recession, the actual unemployment rate rises above the natural rate. In a boom, the actual unemployment rate falls below the natural rate. U.S. Unemployment, 1958-2002 A first model of the natural rate Notation: L = # of workers in labor force E = # of employed workers U = # of unemployed U/L = unemployment rate Assumptions: 1. L is exogenously fixed. 2. During any given month, s = fraction of employed workers that become separated from their jobs, f = fraction of unemployed workers that find jobs. The transitions between employment and unemployment The steady state condition Definition: the labor market is in steady state, or long-run equilibrium, if the unemployment rate is constant. The steady-state condition is: Solving for the “equilibrium” U rate f ?U = s ?E = s ?(L –U ) = s ?L – s ?U Solve for U/L: (f + s)?U = s ?L so, Example: Each month, 1% of employed workers lose their jobs (s = 0.01) Each month, 19% of unemployed workers find jobs (f = 0.19) Find the natural rate of unemployment: policy implication A policy that aims to reduce the natural rate of unemployment will succeed only if it lowers s or increases f. Why is there unemployment? If job finding were instantaneous (f = 1), then all spells of unemployment would be brief, and the natural rate would be near zero. There are two reasons why f 1: 1. job search 2. wage rigidity Job Search Frictional Unemployment frictional unemployment: caused by the time it takes workers to search for a job occurs even when wages are flexible and there are enough jobs to go around occurs because workers have different abilities, preferences jobs have different skill requirements geographic mobility of wo