Copy or Coincidence? A Model for Detecting Social Influence and Duplication Events

In this paper, we analyze the task of inferring rare links between pairs of entities that seem too similar to have occurred by chance. Variations of this task appear in such diverse areas as social network analysis, security, fraud detection, and entity resolution. To address the task in a general form, we propose a simple, flexible mixture model in which most entities are generated independently from a distribution but a small number of pairs are constrained to be similar. We predict the true pairs using a likelihood ratio that trades off the entities’ similarity with their rarity. This method always outperforms using only similarity; however, with certain parameter settings, similarity turns out to be surprisingly competitive. Using real data, we apply the model to detect twins given their birth weights and to re-identify cell phone users based on distinctive usage patterns.