Economic Change and the Aggregate Production Function

The aggregate production function is at the center of contemporaneous macroeconomics. Both growth and business cycle theories offer predictions that depend on the specification of the aggregate technology. In this paper I postulate that the specification of the aggregate technology is endogenous and I study if the aggregate production function mutates in response to changes in the economic environment. To some extent the previous statement is obvious: the aggregate production function is, leaving existence issues aside, the aggregation of all the micro-technologies present in the economy. If the micro-technologies change in time so should do the aggregate technology. I define the aggregate short-run technology and the aggregate long-run technology respectively a mapping from the variable input to output and a mapping from aggregate investment to future capacity. To study mutations that affect short run fluctuations I consider the aggregate output elasticity with respect to the labor supply shocks. To study mutations that affect the long-run I consider the elasticity of capacity with respect to investment. I use a detailed dataset that covers the US manufactirung sector. The results show that the short-run elasticity does not appear to have changed in the sample while the long-run as increased. Finally I show that the long-run technology is a complicated function but that is well approximated by a Cobb-Douglas