Emergence of Power Laws in Online Communities: The Role of Social Mechanisms and Preferential Attachment


MIS Quarterly

September 2014, vol. 38, n°3, pp.795-823

Departments: Information Systems and Operations Management, GREGHEC (CNRS)

Keywords: Online communities, scale-free, power-law distribution, preferential attachment, social exchange, reciprocity, simulation

Online communities bring together individuals with shared interest in joint action or sustained interaction. Power lawdistributions of user popularity appear ubiquitous in online communities but their formation mechanisms are not wellunderstood. This study tests for the formation of power law distributions via the mechanisms of preferential attachment,least efforts, direct reciprocity, and indirect reciprocity. Preferential attachment, where new entrants favor connectionswith already popular participants, is the predominant explanation suggested by prior literature. Yet, the attribution ofpreferential attachment or any other mechanism as a single unitary reason for the emergence of power law distributionsruns contrary to the social nature of online communities and does not account for diversity of participants’ motivation.Agent-based modeling is used to test if a single social mechanism alone or multiple mechanisms together can generatepower law distributions observed in online communities. Data from 28 online communities is used to calibrate, validate,and analyze the simulation. Simulated communication networks are randomly generated according to parameters foreach hypothesis. The fit of the power law distribution in the model testing subset is then compared against the fit forthese simulated networks. The major finding is that, in contrast to research in more general network settings, neitherpreferential attachment nor any other single mechanism alone generates a power law distribution. Instead, a blendedmodel of preferential attachment with other social network formation mechanisms was most consistent with power lawdistributions seen in online communities. This suggests the need to move away from stylized explanations of networkemergence that rely on single theories toward more highly socialized and multitheoretic explanations of communitydevelopment