International Knowledge Diffusion and Home-bias Effect: Do USPTO and EPO Patent Citations Tell the Same Story?*

This paper estimates the international diffusion of technical knowledge using patent citations. We control for self-citations and for procedural differences between patent offices using equivalent patents. We find that (1) there are clear biases in patent examination processes that generate citations in the two offices; (2) at the EPO there is a strong localization effect at the country level, and the size is comparable to that found at the USPTO; (3) technological fields have different properties of diffusion in the two patent offices that do not depend on a patent office bias; (4) using EPO data, the US is not the leading country in terms of citations made and received, as occurs at the USPTO.