Inventor Mobility and Technology Diffusion as Evidenced in Patent Data

This paper analyses the nature of knowledge spillovers from research and development in the field of liquid crystal display technology as evidenced in citations of US patents filed during the twenty year period 1976–1995. By considering the role of inventors' mobility in facilitating the flow of ideas across space and innovating organizations, the paper adds a new dimension to the existing literature, which distinguishes between rent spillovers transmitted through trade in goods and pure knowledge spillovers transmitted through non-market channels. The paper argues that theoretical insights about the sources of sub-optimal growth in models of endogenous technological change cannot inform policy unless the relative importance of different spillover channels is determined empirically. The study therefore estimates a discrete choice model identifying the impact of inventors' changing organizational and collaborative affiliations on the probability of patent citations, controlling for geographic localization effects. This approach provides more detailed evidence on the underlying mechanisms of knowledge spillovers than previous studies of patent citations. Finally, the paper discusses implications for technology policy.