Kwon R, et al. - Using a panel dataset (1990 to 2015) of 3,144 counties in the United States, researchers evaluated the link between income inequality and mass shootings across these counties. They used the US Bureau of the Census to obtain socioeconomic data. They extracted mass shootings data from 3 databases that collect its information from the Federal Bureau of Investigation and media sources, respectively. They found that the likelihood to experience mass shootings is more in counties with growing levels of income inequality. One possible reason for this could be that an environment of anger and resentment is fostered by income inequality, finally resulting in violence.