Patent Citations and the Size of the Inventive Step - Evidence from Hybrid Corn

49 Pages Posted: 10 Aug 2015 Last revised: 2 Sep 2015

See all articles by Petra Moser

Petra Moser

NYU Stern Department of Economics; National Bureau of Economic Research (NBER)

Joerg Ohmstedt

Bain & Company; Cornell University - Department of Economics

Paul W. Rhode

University of Michigan at Ann Arbor; National Bureau of Economic Research (NBER)

Multiple version iconThere are 3 versions of this paper

Date Written: July 2015

Abstract

Patents are the main source of data on innovation, but there are persistent concerns that patents may be a noisy and biased measure. An important challenge arises from unobservable variation in the size of the inventive step that is covered by a patent. The count of later patents that cite a patent as relevant prior art – so called forward citations – have become the standard measure to control for such variation. Citations may, however, also be a noisy and biased measure for the size of the inventive step. To address this issue, this paper examines field trial data for patented improvements in hybrid corn. Field trials report objective measures for improvements in hybrid corn, which we use to quantify the size of the inventive step. These data show a robust correlation between citations and improvements in yields, as the bottom line measure for improvements in hybrid corn. This correlation is robust to alternative measures for improvements in hybrid corn, and a broad range of other tests.We also investigate the process, by which patents generate citations. This analysis reveals that hybrids that serve as an input for genetically-related follow-on inventions are more likely to receive self-citations (by the same firm), which suggests that self-citations are a good predictor for follow-on invention.

Suggested Citation

Moser, Petra and Ohmstedt, Joerg and Rhode, Paul W., Patent Citations and the Size of the Inventive Step - Evidence from Hybrid Corn (July 2015). NBER Working Paper No. w21443. Available at SSRN: https://ssrn.com/abstract=2641659

Petra Moser (Contact Author)

NYU Stern Department of Economics ( email )

44 West 4th Street
New York, NY 10003
United States

National Bureau of Economic Research (NBER)

1050 Massachusetts Avenue
Cambridge, MA 02138
United States

Joerg Ohmstedt

Bain & Company ( email )

Two Copley Place
Boston, MA 02118
United States

Cornell University - Department of Economics ( email )

414 Uris Hall
Ithaca, NY 14853-7601
United States

Paul W. Rhode

University of Michigan at Ann Arbor ( email )

500 S. State Street
Ann Arbor, MI 48109
United States

National Bureau of Economic Research (NBER)

1050 Massachusetts Avenue
Cambridge, MA 02138
United States

Register to save articles to
your library

Register

Paper statistics

Downloads
19
Abstract Views
452
PlumX Metrics