1 R & D Spillovers : The ' Social Network ' of Open Source Software

Knowledge spillovers are a central part of knowledge accumulation. The open source model is a form of software development with source code that is typically made available to all interested parties. At the core of this process is a decentralized production process. Using data from Sourceforge.net, the largest repository of Open Source Software (OSS) projects and contributors on the Internet, we construct a two-mode network; a Project network and a Contributor network. Knowledge spillovers may be closely related to the structure of such networks, since contributors who work on the same project(s) may exchange information and knowledge. Defining the number of downloads as output we find that centrality measures of projects (in the projects network) and of developers (in the developers network) are positively associated with the number of downloads of projects. These results imply that knowledge spillovers play an important role in the development of the OSS projects.