DIRECT VALIDATION OF CITATION COUNTS AS INDICATORS OF INDUSTRIALLY IMPORTANT PATENTS

A new and direct validation study of the use of patent citation analysis in corporate technological assessment is reported, in which a strong association was found between citation counts for highly cited U.S. patents and knowledgeable peer opinion as to the technical importance of the patents. A set of 20 researchers and research managers at Eastman Kodak, all of whom are working in the area of silver halide technology, were asked to each rate the technical impact and importance of each patent in overlapping sets of Eastman Kodak silver halide patents. A total of 77 patents had been selected for rating from 129 silver halide technology patents issued by the U.S. Patent and Trademark Office to Eastman Kodak in 1982 and 1983. The patents ranged from those receiving zero citations, to highly cited patents, cited 10 or more times on the front pages of subsequent U.S. patents issued through 1988. Amongst the infrequently cited patents there were no statistically significant differences between the peer and citation ratings, although there was a rather steady, small progression of both ratings. However, in contrast to the small differences at the low citation end, the group of highly cited patents were rated far more highly by the evaluators, with a difference in ratings that was statistically significant. This directly shows that highly cited patents are of greater technical importance than less frequently cited patents, in the opinion of knowledgeable peer researchers'and inventors, and thereby supports the growing use of patent citation indicators in assessing the technological importance of a company's patent portfolio. © 1991.