Software Patent Citations: A Consistent Weighted Ranking

Intellectual Property and Patents

Article Snapshot


Chaim Fershtman and Neil Gandal


Chapter in Industrial Organization and the Digital Economy, Gerhard Illing and Martin Peitz eds., MIT Press, 2006


This paper looks at how to measure the quality of software patents.

Policy Relevance

Many observers believe that weak software patents are blocking innovation. Measuring how valuable software patents are encourages an understanding of whether patents do more harm than good.

Main Points

  • Patents sometimes refer to, or “cite,” earlier patents. Experts have used the number of times a patent is cited as an estimate of its value. But close examination of some patents suggest it is not a very good estimate.
  • Firms might cite or avoid citing patents for strategic reasons, such as wanting to avoid delaying the grant of their patent by referring to an earlier, very complex patent.
  • Citations to Patent A by Patent B should be most heavily weighted if patent B also receives many citations.
  • The authors find that their weighted system is a better indicator of patent value than simply counting patent citations.  

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