Firm strategic behavior and the measurement of knowledge flows with patent citations

This research addresses firms' use of external knowledge sources to develop patented inventions and explores the validity of patent citations as an indicator of interfirm knowledge flows. By comparing patent citations with primary data reported by the inventors, we uncover systematic measurement errors in patent citations and show that they depend on the firms' patent strategies (e.g., to reduce the risk of imitation or litigation), the source of knowledge employed (e.g., competitors, users), the technology of the underlying invention, and the institutional characteristics of the patent system. Our findings about the role of these factors in external knowledge sourcing and citing propensity highlight the importance of firms' strategic behavior and offer novel insights for the use of patent citations as an indicator of knowledge flows.