A Survival Analysis of the Approval of U.S. Patent Applications
We model the length of time that it takes for a patent application to be granted by the U.S. Patent and Trademark Office, conditional on the patent actually being awarded eventually. Survival analysis is applied and both the nonparametric Kaplan-Meier and parametric accelerated failure time models are used to analyze the data. We find that the number of claims a patent makes, the number of citations a patent makes, the patent’s technological category, and the type of applicant all have significant effects on the duration that a patent is under consideration. A log-normal survival model is the preferred parametric specification, and the results suggest that the hazard function is non-monotonic over time.
|Date of creation:||24 Aug 2007|
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- Kennan, John, 1985. "The duration of contract strikes in U.S. manufacturing," Journal of Econometrics, Elsevier, vol. 28(1), pages 5-28, April.