Looking for International Knowledge Spillovers a Review of the Literature with Suggestions for New Approaches

This paper reviews the recent empirical literature on international knowledge spillovers. I start by summarizing the theoretical models that have highlighted the potential importance of these spillovers. Then, drawing upon the older micro productivity research tradition, I lay out a simple conceptual framework (though not a formal theoretical framework) for thinking about the various kinds of knowledge transfers that may exist, how they might be mediated, and the means by which their effects might be traced empirically. I then review some influential empirical papers, demonstrating that empirical work to date may very well not have identified the effects the authors set out to measure. Finally, I describe some promising new approaches which may allow researchers in this field to identify more precisely, both conceptually and empirically, certain kinds of international knowledge spillovers. Les externalites internationales de connaissance : survol de litterature et suggestions pour de nouvelles approches RESUME. L'article fait le tour de la litterature empirique r6cente relative aux externalites internationales de connaissance. Je commence par resumer les articles theoriques qui ont bien fait apparaltre l'importance que pouvait avoir de telles externalites. En me fondant ensuite sur la tradition plus ancienne des recherches micro6conomiques en matiere de productivit6, je propose un cadre conceptuel simple (pas un modele theorique) pour refl6chir sur les diff6rents types possibles de transferts de connaissances, la fagon dont ils pourraient etre contr6l6s, et les moyens de les rep6rer empiriquement. Je presente un certain nombre d'investigations empiriques pr6sentees dans des articles importants, montrant qu'elles n'ont sans doute pas identifi6es v6ritablement les effets qu'elles cherchaient a mesurer. Enfin je d6cris des approches nouvelles qui pourraient permettre aux chercheurs d'identifier plus pr6cis6ment, conceptuellement et empiriquement, certaines des formes d'externalit6s internationales de connaissance. * L. G. BRANSTErrER: U. C. Davis, NBER. The ideas expressed in this paper owe a substantial intellectual debt to discussions with Bee-Yan Aw, Magnus Blomstrom, Akira Goto, Ann Harrison, Adam Jaffe, Wolfgang Keller, Sam Kortom, Pierre Mohnen, Manuel Trajtenberg, Daniel Trefler, Ryuhei Wakasugi, Larry Westphal, and, especially, Zvi Griliches. I also thank two anonymous referees for their insightful comments. I note that parts of this paper draw heavily from my 1996 working paper, "Are Knowledge Spillovers Intranational or International in Scope?", and my 1996 Harvard Ph.D. thesis. All mistakes, errors, and misunderstandings are my own fault.