Under the traditional interpretation of macroeconomic fluctuations, aggregate demand shocks move output and prices in the same direction, while aggregate supply shocks move output and prices in opposite directions. This paper examines the joint behavior of U.S. output, unemployment, prices, wages, and nominal money and asks whether it is consistent with this interpretation. The answer is a qualified yes.

Understanding inventory movements is central to an understanding of business cycles. This paper presents an empirical study of the behavior of inventories in the automobile industry. It finds that inventory behavior is well explained by the assumption of intertemporal optimization with rational expectations. The underlying cost structure appears to have substantial costs of changing production as well as substantial costs of being away from target inventory, thelatter being a function of current sales. Given this cost structure, whether inventory behavior is stabilizing or destabilizing depends on the characteristics of the demand process. In the automobile industry, inventory behavior is destabilizing: the variance of production is larger than the variance of sales.