Working Paper: NBER ID: w3993
Authors: Adam B. Jaffe; Manuel Trajtenberg; Rebecca Henderson
Abstract: We compare the geographic location of patent citations to those of the cited patents, as evidence of the extent to which knowledge spillovers are geographically localized. We find that citations to U.S. patents are more likely to come from the U.S., and more likely to come from the same state and SMSA as the cited patents than one would expect based only on the preexisting concentration of related research activity. These effects are particularly significant at the local (SMSA) level, and are particularly apparent in early citations.
Keywords: knowledge spillovers; patent citations; geographic localization
JEL Codes: O31; R11
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| Geographic proximity (R12) | Knowledge spillovers (O36) |
| Citations from U.S. patents (O34) | Same state or SMSA as cited patents (L96) |
| Early citations (Y20) | Stronger localization effects (F69) |
| Localized citations (Y50) | Exceed control frequency (Y60) |