Taking Keller seriously: trade and distance in international R&D spillovers

In a much cited paper, Wolfgang Keller (Are international R&D spillovers trade-related? Analyzing spillovers among randomly matched trade partners, European Economic Review, 48, 1469-1481, 1998) claims that international R&D spillovers are global and trade-unrelated. In following works, Keller revisits his position and maintains that spillovers are localized because the tacit nature of knowledge favors the direct interaction among agents. Whether the international R&D spillovers are global and trade-related still remains a debated issue in the empirical literature. By adopting two empirical specifications that nest Keller’s models, we i) reject the hypothesis that international R&D spillovers are global and ii) show that these latter depend on both geographical distance and international trade.