Direct and indirect knowledge spillovers: The "social network" of open-source projects

Knowledge spillovers are a central part of knowledge accumulation. The article focuses on spillovers that occur through the interaction between different researchers or developers who collaborate on different research projects. The article distinguishes between project spillovers and contributors' spillovers and between direct and indirect spillovers. The article constructs a unique data set of open source software projects. The data identify the contributors who work on each project and thus enable us to construct a two-mode network: a project network and a contributor network. The article demonstrates that the structure of these networks is associated with project success and that there is a positive association between project closeness centrality and project success. This suggests the existence of both direct and indirect project knowledge spillovers. We find no evidence for any association between contributor closeness centrality and project success, suggesting that contributor spillovers play a lesser role in project success.