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Eller College Home > McGuire Center for Entrepreneurship > CRIE > Road Map > Longitudinal Patent Tables
Commercialization Research on Innovation and Entrepreneurship

Longitudinal Patent Tables

Forward-citation analysis is commonly used to measure the value of innovation (Trajtenberg 1990) or the diffusion of knowledge (Jaffe et al. 1993). Seldom, if ever, has this measure been treated longitudinally (Shaffer 2011). Below, we outline current data available for academic analyses.

Proposed Priorities for Longitudinal Secondary Data

Annual Forward-citation counts

Beginning in 1975, for each patent, we have compiled the number of forward-citations received each year. If the patent could potentially have a forward citation, it will receive a score of zero. If not (meaning the patent doesn't exist yet), the value for the year will be empty.


Below you will find details comparing Patent Rank to Trajtenberg's forward-citation counts:


 1 Trajtenberg (1990)3 Shaffer (2011)
Weighting SchemaForward CitationsPatent Rank
Weighting LogicNot all patents are equal, so let's weight them by their subsequently cited patents.If not all patents are equal, why would we equally weight subsequently cited patents?
Network MathematicsIndegree CentralityEigenvector Centrality
Network EffectsImportance EffectsTotal Effects

Because Patent Rank represents a more robust mathematical model for network centrality, we posit that the forward-citation metric creates systematic bias in determining value which has deleteriously influenced our study of innovation and entrepreneurship. The recursive weighting used in Patent Rank provides a more precise measure of value than forward-citation counts.

1. Trajtenberg, Manual. 1990. A Penny for Your Quotes: Patent Citations and the Value of Innovations. The RAND Journal of Economics 21(1) pp. 172—187.

2. Jaffe, Adam B., Manuel Trajtenberg, Rebecca Henderson. 1993. Geographic Localization of Knowledge Spillovers as Evidenced by Patent Citations. The Quarterly Journal of Economics 108(3) pp. 577-598.

3. Shaffer, Monte J. 2011. Entrepreneurial Innovation: Patent Rank and Marketing Science. Dissertation: Washington State University.

Annual Patent Rank scores

As outlined above, Patent Rank recursively weights all forward and backward citations to determine the patent's intrinsic value within the patent network. Annually, we can compute these scores cumulatively (total diffusion since introduction in the network) or marginally (what has been the influence in a recent network [e.g., the last 5 years]). Additionally, we can compute the scores just using the citations (structure) or we can utilize the citations and their strength (combined4).



4. Each link is defined by its presence and strength: the strength is defined by a ClassMatch algorithm which is a softmatch of technological-classification overlap between the two patents that define the link More details can be found in Shaffer (2011), see above.

Other longitudinal data (ideas are welcome)

The success of CRIE will be dependent on its adoption by academics. Tell your friends. Create an account. Use the system. Provide feedback on what you like, what other data you would like to see, and how we can improve. Your feedback is essential for CRIE's success and ultimately better academic research using patent data.

For additional information, please contact us.

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