An examination of data on output and labor input reveals that some U.S. industries have marginal cost well below price. The conclusion rests on the finding that cyclical variations in labor input are small compared with variations in output. In booms, firms produce substantially more output and sell it for a price that exceeds the costs of the added inputs. The paper documents the disparity between price and marginal cost, where marginal cost is estimated from annual variations in cost. It considers a variety of explanations of the findings that are consistent with competition, but none is found to be completely plausible.

One of the important determinants of the response of saving and consumption to the real interest rate is the elasticity of intertemporal substitution. That elasticity can be measured by the response of the rate of change of consumption to changes in the expected real interest rated. A detailed study of data for the twentieth-century United States shows no strong evidence that the elasticity of intertemporal substitution is positive. Earlier findings of substantially positive elasticities are reversed when appropriate estimation methods are used.

[The effects of an unexpected change in income taxes are studied in a model with full rational expectations. In the short run, aggregate supply is quite price elastic because commitments to pay predetermined wages are made 1 or more years in advance. The model also recognizes the limited response of investment to unexpected developments in the short run. The paper finds that much of the effect of unexpected tax policy operates through inflationary expectations--an economy with rational expectations is more responsive to tax changes than is one with naive expectations.]

Optimization of the part of consumers is shown to imply that the marginal utility of consumption evolves according to a random walk with trend. To a reasonable approximation, consumption itself should evolve in the same way. In particular, no variable apart from current consumption should be of any value in predicting future consumption. This implication is tested with time-series data for the postwar United States. It is confirmed for real disposable income, which has no predictive power for consumption, but rejected for an index of stock prices. The paper concludes that the evidence supports a modified version of the life cycle--permanent income hypothesis.

Recessions appear to be times when the marginal rate of substitution between goods and workers’ time falls below the marginal product of labor. If so, the allocation of workers’ time is inefficient. I develop a model of households and production that reconciles cyclical movements in the marginal value of time and the marginal product. The model embodies the findings of research that the Frisch elasticity of labor supply is less than one. It treats unemployment in a search‐and‐matching setup. Recessions do not result in private inefficiency in the allocation of labor, but the unemployment rate may be socially inefficiently high.

An examination of data on output and labor input reveals that some U.S. industries have marginal cost well below price. The conclusion rests on the finding that cyclical variations in labor input are small compared with variations in output. In booms, firms produce substantially more output and sell it for a price that exceeds the costs of the added inputs. This paper documents the disparity between price and marginal cost, where marginal cost is estimated from annual variations in cost. It considers a variety of explanations of the findings that are consistent with competition, but none is found to be completely plausible.

One of the important determinants of the response of saving and consumption to the real interest rate is the ela sticity of intertemporal substitution. That elasticity can be measure d by the response of the rate of change of consumption to changes in the expected real interest rate. A detailed study of data for the twe ntieth-century United States shows no strong evidence that the elasti city of intertemporal substitution is positive. Earlier findings of s ubstantially positive elasticities are reversed when appropriate esti mation methods are used.

The effects of an unexpected change in income taxes are studied in a model with full rational expectations. In the short run, aggregate supply is quite price elastic because commitments to pay predetermined wages are made 1 or more years in advance. The model also recognizes the limited response of investment to unexpected developments in the short run. The paper finds that much of the effect of unexpected tax policy operates through inflationary expectations--an economy with rational expectations is more responsive to tax changes than is one with naive expectations.