Research Lags and Spillovers

Abstract

Modeling and measuring the productivity consequences of R&D is a tricky business. The challenge in attributing productivity to R&D is to establish which research, conducted by whom, and when, was responsible for a particular productivity increase. In other words, in modeling the effects of research on agricultural productivity the two principal areas of difficulty are in the treatment of knowledge spillovers (i.e., the “by whom” part of the attribution problem) and in identifying the lag structure linking research spending, knowledge stocks, and productivity (i.e., the “when” part).