## u* = √uv

This paper argues that in the United States the full-employment rate of unemployment (FERU) is the geometric average of the unemployment and vacancy rates. Between 1930 and 2023, the FERU averages 4.1% and is very stable.

This paper argues that in the United States the full-employment rate of unemployment (FERU) is the geometric average of the unemployment and vacancy rates. Between 1930 and 2023, the FERU averages 4.1% and is very stable.

This course presents a matching model of unemployment. It uses the model to study unemployment fluctuations; job rationing; efficient unemployment and unemployment gap; and labor market policies such as minimum wage, public employment, and unemployment insurance.

This graduate course presents various matching models of economic slack. It uses them to study business-cycle fluctuations; Keynesian, classical, and frictional unemployment; optimal monetary policy and the zero lower bound; and optimal government spending.

This paper explains why a wave of immigration reduces the employment rate of native workers, and why this reduction is larger in bad times. Yet, immigration improves native welfare when the labor market is inefficiently tight, because it helps firms to recruit.

This paper develops a sufficient-statistic formula for the unemployment gap. The formula depends on the elasticity of the Beveridge curve, cost of unemployment, and recruiting cost. In the United States the unemployment gap is countercyclical and often positive.

This undergraduate course introduces macroeconomic concepts—such as GDP and inflation—and covers the IS-LM model of business cycles, matching model of unemployment, Phillips curve, Malthusian model of growth, and Solowian model of growth.

This paper explores how the optimal generosity of unemployment insurance varies over the business cycle in the United States. It finds that the optimal replacement rate is countercyclical, just like the actual replacement rate.

This paper develops a theory of optimal unemployment insurance in matching models. It derives a sufficient-statistic formula for optimal unemployment insurance, which is useful to determine the optimal cyclicality of unemployment insurance.

This paper develops a model of unemployment fluctuations. The innovation is to represent the labor and product markets with a matching structure. The model simultaneously features Keynesian unemployment, classical unemployment, and frictional unemployment.

This paper develops a New Keynesian model in which the government multiplier doubles when the unemployment rate rises from 5% to 8%. The multiplier is so countercyclical because in bad times, on the labor market, job rationing dwarfs matching frictions.

This paper proposes a matching model of the labor market with job rationing: unemployment does not disappear in the absence of matching frictions. In recessions, job rationing drives the rise of unemployment, whereas matching frictions contribute little to it.