Influences of counting methods on country rankings: a perspective from patent analysis

Abstract

The counting of patents and citations is commonly used to evaluate technological innovation and its impact. However, in an age of increasing international collaboration, the counting of international collaboration patents has become a methodological issue. This study compared country rankings using four different counting methods (i.e. whole counting, straight counting, whole-normalized counting, complete-normalized counting) in patent, citation and citation-patent ratio (CP ratio) counts. It also observed inflation depending on the method used. The counting was based on the complete 1992---2011 patent and citation data issued by United States Patent and Trademark Office. The results show that counting methods have only minor effects on country rankings in patent count, citation count and CP ratio count. All four counting methods yield reliable country ranks in technology innovation capability and impact. While the influences of counting methods vary between patent count, citation count and CP ratio count, counting methods may exert slightly greater effects on CP ratio counts than on patent and citation counts. As for the inflation, the distributions of higher and lower inflation by the four counting methods are different in patent, citation and CP ratio counts.