University licensing and the flow of scientific knowledge

•Examines effect of licensing of patents on journal citations to related articles.•Automates Murray’s (2002) “patent-paper pairs” methodology.•Operationalizes a definition of “research tools” that permits empirical analysis.•Finds that licensing has a modest positive effect on citations to related articles.•For research tools, however, finds that licensing corresponds to fewer citations. As university involvement in technology transfer and entrepreneurship has increased, concerns over the patenting and licensing of scientific discoveries have grown. This paper examines the effect that the licensing of academic patents has on journal citations to academic publications covering the same scientific research. We analyze data on invention disclosures, patents, and licenses from the University of California, a leading U.S. academic patenter and licensor, between 1997 and 2007. We also develop a novel “inventor-based” maximum-likelihood matching technique to automate and generalize Murray's (2002) “patent-paper pairs” methodology. We use this methodology to identify the scientific publications associated with University of California patents and licenses. Based on a “difference-in-differences” analysis, we find that within our sample of patented academic discoveries, citations to licensed patent-linked publications are higher in the three years after the license, although this difference is not statistically significant. We then disaggregate our sample into (a) patented discoveries that are likely to be used as “research tools” by other researchers (based on the presence of material transfer agreements (MTAs) that cover them) and (b) patented discoveries not covered by MTAs. Citations to publications linked to licensed patents in the latter subset (not covered by MTAs) are higher for publications linked to licensed patents, and this difference is statistically significant. In contrast, licensing of patented discoveries that are also research tools is associated with a reduction in citations to papers linked to these research advances, raising the possibility that licensing may restrict the flow of inputs to “follow-on” scientific research.