Template-type: ReDIF-Paper 1.0
Author-Name: Lafond, F.
Author-Email: lafond@merit.unu.edu
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.
Classification-JEL: O30, O31
Keywords: Innovation, R&D, Learning, Knowledge, Classification, Categorization,
	 Pareto distribution, Power law
Series: UNU-MERIT Working Papers
Creation-Date: 20140631
Number: 2014-060
File-URL: https://unu-merit.nl/publications/wppdf/2014/wp2014-060.pdf
File-Format: application/pdf
File-Size: 1111 Kb
Handle: RePEc:unm:unumer:2014060