Sloan School of Management
Massachusetts Institute of Technology
Cambridge, MA 02142
Institutional Affiliation: Massachusetts Institute of Technology
NBER Working Papers and Publications
|April 2019||In-Text Patent Citations: A User’s Guide|
with Kevin A. Bryan, Bhaven N. Sampat: w25742
We introduce, validate, and provide a public database of a new measure of the knowledge inventors draw on: scientific references in patent specifications. These references are common and algorithmically extractable. Critically, they are very different from the “front page” prior art commonly used to proxy for inventor knowledge. Only 24% of front page citations to academic articles are in the patent text, and 31% of in-text citations are on the front page. We explain these differences by describing the legal rules and practice governing citation. Empirical validations suggest that in-text citations appear to more accurately measure real knowledge flows, consistent with their legal role.
|September 2016||Technological Leadership (de)Concentration: Causes in ICTE|
with Shane Greenstein: w22631
Using patents as indicators of inventive activity, this article characterizes the concentration of origins of invention from 1976 to 2010, and how these changed over time. The analysis finds pervasive deconcentration in virtually every area related to ICT, but it can explain only a small part of this trend. Deconcentration happens despite the role of lateral entry by existing firms. New firm entry drives part of the deconcentration, but this alone cannot explain the change. A single supply factor in the market for ideas, such as the breakup of AT&T, also cannot explain the trend. Finally, eleven percent of patents change hands through mergers and acquisitions activity, but this does not make up for the declines in concentration in the origins of invention.