Predicting users ’ political support from their Reddit comment history CS 229 Project Final Report

In recent years, the political landscape of the United States has undergone significant changes which are speculated to stem from mass adoption of social media. Most notably, research shows that the overlap between liberal and conservative social networks is surprisingly small. In this project, we test whether the conservative-liberal divide on the Internet is large enough to result in significant differences between the styles of communication of users on either side, even when discussing topics that are not politically charged. To investigate that claim, we selected Reddit users who are highly active on the subreddits dedicated to Donald Trump (r/The_Donald), Hillary Clinton (r/HillaryClinton) and Bernie Sanders (r/SandersForPresident), and labeled them as Trump/Clinton/Sanders supporters accordingly. We then attempted to identify their political inclinations based on the comments they made in non-political subreddits. We repeated the process for their comments in politicallyoriented subreddits. Our results indicate that there is indeed a subtle difference in the Reddit usageand communicationpatterns of Trump, Sanders, and Clinton supporters. Our top algorithms were more accurate when applied to political conversations than when used on non-political comments, which highlights how challenging it is to identify users based on their nonpolitical comment histories.