The Dynamics Of Innovation
The authors analyze social learning and innovation in an overlapping generations model in which available technologies have correlated payoffs. Each generation experiments within a set of policies whose payoffs are initially unknown and drawn from the path of a Brownian motion with drift. Marginal innovation consists in choosing a technology within the convex hull of policies already explored and entails no direct cost. Radical innovation consists in experimenting beyond the frontier of that interval, and entails a cost that increases with the distance from the frontier, and may decrease with the best technology currently available.