Have university knowledge flows narrowed? Evidence from patent data

The rate of university patenting increased dramatically during the 1980s. Did the manner in which knowledge embedded in university patents was managed change during this period of rapid patenting growth? Using a Herfindahl-type measure of knowledge flow concentration and employing a difference-in-differences estimation to compare university-to-firm patent citations across two time periods, we find that the university diffusion premium (the degree to which university knowledge outflows are more widely distributed than those of firms) declined by more than half during the 1980s. In addition, we find that the university diversity premium (the degree to which knowledge inflows used by universities are drawn front a more widely distributed set of prior art holders than those used by firms) also declined by more than half. However, these changes are mostly limited to a narrow set of technology fields (i.e., biotechnology and pharmaceuticals in the outflows case and sub-fields of electronics in the inflows case). The social welfare implications are ambiguous. (C) 2008 Elsevier B.V. All rights reserved.