Multi-layer network analysis of deliberation in an online discussion platform: The case of Reddit

This paper proposes a novel multi-layer network model to study deliberation in online discussion platforms. The model comprises two layers: a discussion layer, which represents as a hierarchical tree the comment-to-comment replies within a given post, and an actor layer, which represents the actor-to-actor reply interactions. The interlayer links represent user-comment ownership. We use this network model to extend González-Bailón et al. (2010)’s foundational network analysis of argumentation and representation in discussion, by proposing two network metrics to measure the potential for deliberation in discussion threads. We also propose a new approach for identifying the boundaries that determine whether a given post is identified as deliberative, and for comparing the level of deliberation of collections of posts. We apply our new approach to a large Reddit dataset containing posts from 72 subreddits focused on different topics and demonstrate that our new metrics have construct validity in that observed differences in measured deliberation across categories of subreddits can be explained by the topics and purpose of the subreddits. While we find that some political subreddits exhibit high levels of deliberation thus indicating that online political talk can meet the prerequisites for deliberation, the level of deliberation in regional and sports subreddits was even higher. Analysis of the actor layer shows correlations between the deliberation measured on the discussion layer, and classical network metrics of the actor layer including degree distribution, assortativity, and the global clustering coefficient. These correlations reveal important insights into how the aggregate behaviour of users is related to deliberation.