Are Mass Shootings in the U.S. Increasing? Understanding How Differing Definitions of Politically Charged Events Impact People's Perceptions of Expected Trends in Visualizations.

Visualizations of mass shooting incidents in the United States appearing in the media can influence people's beliefs and attitudes. However, different data sources each use their own definition of mass shootings, resulting in varying counts and trends of these incidents across the sources. To investigate the effects of these varying definitions on public perceptions, we conducted a crowdsourced study using data from four sources-Mother Jones, Mass Shooter Database, Everytown for Gun Safety, and The Washington Post.