Co, Catherine; Wohar, Mark - In: Economics of Innovation and New Technology 13 (2004) 2, pp. 101-126
This paper employs unit root tests that allow for two endogenously determined structural breaks to study whether or not invention activities are converging across US regions/states. Using US patent data from 1929 to 1997, we find technological β-convergence in six of the nine Census regions, in...