The Healing Arts: Analysis of the Knowledge Flows between Successive Generations of Innovation in the Pharmaceutical Sector

This paper examines the location of innovations within pharmaceutical technology, using U.S. patent citation data to trace the knowledge flows over time. It is clear that knowledge clustering is certainly present. Our study utilizes multivariate left-censored Tobit regression analysis to control for identifiable factors, to examine whether over time the distance between successive innovators has changed. We find the distance to be increasing significantly over time, both when considering all citations and only inter-city transfers.