Template-type: ReDif-Paper 1.0
Author-Name: Lafond F.D. 
Author-workplace-name: UNU-MERIT
Title: The size of patent categories: USPTO 1976-2006
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: Technological Change; Research and Development; Intellectual Property Rights: General; Innovation and Invention: Processes and Incentives; 
Classification-JEL: O30; O31; .
Series:  Working Papers
Creation-Date: 2014
Number: 060
File-URL: http://pub.maastrichtuniversity.nl/09f1922c-5343-4860-b33a-09a4c6dbb3fb
File-Format: application/pdf
File-Size: 1111673
Handle: RePEc:unm:unumer:2014060