All Things Considered: Detecting Partisan Events from News Media with Cross-Article Comparison

TL;DR

This paper introduces a novel framework that uses cross-article comparison to detect partisan events in news media, revealing subtle media biases that influence public opinion.

Contribution

It develops a latent variable model for predicting article ideology by comparing multiple articles on the same story to identify partisan event selection.

Findings

Partisan event selection exists even among mainstream media.

Cross-article comparison improves detection of partisan bias.

The framework outperforms existing baselines in identifying media bias.

Abstract

Public opinion is shaped by the information news media provide, and that information in turn may be shaped by the ideological preferences of media outlets. But while much attention has been devoted to media bias via overt ideological language or topic selection, a more unobtrusive way in which the media shape opinion is via the strategic inclusion or omission of partisan events that may support one side or the other. We develop a latent variable-based framework to predict the ideology of news articles by comparing multiple articles on the same story and identifying partisan events whose inclusion or omission reveals ideology. Our experiments first validate the existence of partisan event selection, and then show that article alignment and cross-document comparison detect partisan events and article ideology better than competitive baselines. Our results reveal the high-level form of media bias, which is present even among mainstream media with strong norms of objectivity and nonpartisanship. Our codebase and dataset are available at https://github.com/launchnlp/ATC.