The overlooked citations: Investigating the impact of ignoring citations to published patent applications

Abstract

Abstract A utility patent application may result in two citable documents: a published patent application (PPA) and a patent if the application is granted. Most analytic works consider only citations to the patent and ignore those to the PPA. This study gathers more than 270,000 U.S. utility patents granted in 2014 and their PPAs, and compares their citation counts up to 2018. Statistics show that citations to patents, on the average, account for less than 50 % of those to the patents and their PPAs combined together, indicating a significant underestimation to the value or impact of the patents. The degree of depreciation is worse when the time gaps between patents and their PPAs are longer, as the PPAs not only have accumulated citations for a longer period, but also individually, concurrently, and continuously receive citations after the patent is granted. This study further applies Main Path Analysis to a conventional citation network involving only citations to the patents and another network augmented with those to the PPAs, using empirical data from United States Patent and Trademark Office (USPTO) Cancer Moonshot Patent Data. The main path derived from the augmented network is almost entirely different from that of the conventional network.