The Effect of Technological Impact upon Patent Renewal Decisions

Abstract

This paper analyzes the relationship between the technological impact of US patents, as measured using patent citation analysis, and the renewal decisions made by their owners. A significant positive relationship was discovered between these variables across a number of time periods. For example, 60% of patents uncited in the first eight years after publication were renewed at that point, compared with over 90% of patents cited more than 50 times in the first eight years. The relationship between citations and renewals remained highly significant even after controlling for differences between internal and external citations, and differences in technologies and patent ownership. Further analysis was undertaken into the relative influence of technological impact and maintenance costs upon renewal decisions. This analysis revealed that after patent maintenance fees were doubled for patents applied for after August 1982, a larger proportion of patents was maintained at each renewal point despite the increase. These patents also had a greater technological impact than patents applied for prior to the increase in maintenance fees, reflected by the larger number of citations they received. It may thus be inferred that the technological impact of patents had a greater influence upon renewal decisions than economic concerns regarding the costs of their renewal.