Costs of Adjustment, the Aggregation Problem and Investment.

This paper looks at the empirical consequences of inappropriately using a representative firm to mimic the aggregate investment decisions of a group of heterogeneous firms faced with costs of adjusting capital inputs. Improper aggregation generates a bias with two important consequences: (1) an apparent insensitivity of the aggregate capital stock to the user cost of capital and (2) predicted responses of the capital stock to shocks that are considerably slower than observed. Both of these consequences are features of available investment equations. Copyright 1992 by MIT Press.