Patent Citations—An Analysis of Quality Differences and Citing Practices in Hybrid Corn
将杂交玉米田间试验的客观性能数据与专利引用关联，检验了专利引用作为创新质量代理指标的有效性，发现引用与性能正相关，但律师和审查员的引用实践也会影响引用计数。
A growing empirical literature uses patent citations as a quality-adjusted measure for innovation, despite concerns about the validity of this measure. This paper links patents with objective measures of improvements in the quality of patented inventions—measured through performance in field trials for hybrid corn—to examine three potential factors that influence citations: (1) improvements in performance, (2) citing practices of patent attorneys, and (3) citing practices of patent examiners. This analysis reveals that citations are robustly correlated with performance, which confirms that citations are a useful quality-adjusted measure for innovation. The citing practices of patent attorneys and examiners, however, also influence citations. Patent attorneys cite early patents, which help establish the patentability of an invention; this practice may inflate citation counts for early patents, particularly for inventions that have only recently become patentable. Attorneys also add self-citations; our analysis indicates that self-citations are an indicator of follow-on invention. By comparison, examiner-added citations are typically unrelated to improvements in performance or follow-on invention. Data and the online appendix are available at https://doi.org/10.1287/mnsc.2016.2688 . This paper was accepted by Lee Fleming, entrepreneurship and innovation.