The size of patent categories: USPTO 1976-2006

François Lafond

No 2014-060, MERIT Working Papers from United Nations University - Maastricht Economic and Social Research Institute on Innovation and Technology (MERIT)

Abstract: Categorization is an important phenomenon in science and society, and classification systems reflect the mesoscale organization of knowledge. The Yule-Simon-Naranan model, which assumes exponential growth of the number of categories and exponential growth of individual categories predicts a power law Pareto size distribution, and a power law size-rank relation Zipfs law. However, the size distribution of patent subclasses departs from a pure power law, and is shown to be closer to a shifted power law. At a higher aggregation level patent classes, the rank-size relation deviates even more from a pure power law, and is shown to be closer to a generalized beta curve. These patterns can be explained by assuming a shifted exponential growth of individual categories to obtain a shifted power law size distribution for subclasses, and by assuming an asymmetric logistic growth of the number of categories to obtain a generalized beta size-rank relationship for classes. This may suggest a shift towards incremental more than radical innovation.

Keywords: Innovation; R&D; Learning; Knowledge; Classification; Categorization; Pareto distribution; Power law (search for similar items in EconPapers)
JEL-codes: O30 O31 (search for similar items in EconPapers)
Date: 2014-06-30
New Economics Papers: this item is included in nep-ino, nep-ipr and nep-pr~
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Citations: View citations in EconPapers (2)

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