Patent citations have become an acceptable proxy for inventions’ quality. Our study offers the first systematic exploration of uncited patents. Analyzing data on all US patents issued between 1976 and 2008, we examine the ratio of uncited patents out of all patents granted each year. We find a robust pattern, consistent across technological fields, whereby the percentage of uncited patents declined between 1976 and the mid-1990s, but has been significantly increasing since then. We discuss policy implications of these findings and suggest that the ratio of uncited patents can serve as a complementary measure for evaluating the patent system.

专利引用已经成为发明质量的可接受代表。我们的研究提供了对未引用专利的首次系统性探索。通过分析1976年至2008年之间发布的所有美国专利的数据，我们检查了每年被授予的所有专利中未引用专利的比率。我们发现一种稳健的模式，在各个技术领域都保持一致，未引用专利的百分比在1976年至1990年代中期之间有所下降，但此后一直在显着增加。我们讨论了这些发现的政策含义，并建议未引用专利的比例可以作为评估专利制度的补充措施。