of externalities of both Marshall and Jacobs' type. Further factors influencing efficiency are spillovers within the …

endogeneity concerns. We analyze a broad set of workhorse models of firm interactions and show that spillovers naturally arise in … random treatment, spillovers lead to an intricate bias, ii) fixed effects can exacerbate the spillover-induced bias. We …

so by using R&D and patent data for eighty-six European Regions in the 1977-1995 period. We find that spillovers exist …, different specifications of distance functions, country and border effects. The size of these spillovers is small, though … personal contacts. This interpretation is reinforced by the finding that the spillovers are somewhat weaker across national …