Discovering Political Topics in Facebook Discussion threads with Graph Contextualization
This work addresses the challenge of understanding political discourse on social media for researchers, but it is incremental as it builds on existing spectral clustering methods by adding text contextualization.
The authors tackled the problem of analyzing political engagement on Facebook during the 2012 French presidential election by developing a graph contextualization method called pairGraphText, which separates candidate-centered and issue-centered structures in discussion threads, scaling to hundreds of thousands of nodes and thousands of unique words.
We propose a graph contextualization method, pairGraphText, to study political engagement on Facebook during the 2012 French presidential election. It is a spectral algorithm that contextualizes graph data with text data for online discussion thread. In particular, we examine the Facebook posts of the eight leading candidates and the comments beneath these posts. We find evidence of both (i) candidate-centered structure, where citizens primarily comment on the wall of one candidate and (ii) issue-centered structure (i.e. on political topics), where citizens' attention and expression is primarily directed towards a specific set of issues (e.g. economics, immigration, etc). To identify issue-centered structure, we develop pairGraphText, to analyze a network with high-dimensional features on the interactions (i.e. text). This technique scales to hundreds of thousands of nodes and thousands of unique words. In the Facebook data, spectral clustering without the contextualizing text information finds a mixture of (i) candidate and (ii) issue clusters. The contextualized information with text data helps to separate these two structures. We conclude by showing that the novel methodology is consistent under a statistical model.