Political attitudes differ but share a common low-dimensional structure across social media and survey data

TL;DR

This study reveals that despite issue-specific differences, online social media and survey data in France share a common low-dimensional ideological structure, with polarization and user activity influencing the observed patterns.

Contribution

It demonstrates that social media and survey data exhibit similar bi-dimensional ideological structures and analyzes how user activity and popularity affect polarization and attitude divergence.

Findings

Social media and survey data share a bi-dimensional ideological structure.

Higher activity correlates with reduced dimensionality of attitudes.

User exposure influences the representativeness of social media users.

Abstract

Does polarization online reflect the state of polarization in society? We study ideological positions and attitudes on several issues in France, a country with documented issue nonalignment. We compare distributions on X/Twitter with a nationally representative sample, focusing on two key properties: ideological polarization and issue alignment. Despite significant issue-wise divergences, positions of both the X population and the nationally representative sample present a similar bi-dimensional structure along two dominant bundles of aligned issues: a Left-Right divide, and a Global-Local divide. We then study how our results vary when accounting for key structural parameters of the online public sphere: activity, popularity, and visibility. We find that the dimensionality of attitude distributions shrinks as ideological polarization increases when selecting more active users. The divergence between political attitudes on social media and in survey data is greatly mediated by the combination of activity and popularity of social media users: users benefiting from the most exposure are also the most representative of the general public. Together, our results shed light on the structural similarities and differences between political attitudes from social media users and the general public.