There are several data collections on Mass Shooting. All of the data defines mass shooting in different ways. Some only count incidents where four or more people were killed, others count any where four or more people were shot (whether they died or survived). The problem is that, depending on the criteria, the number of mass shootings that take place each year can range from dozens to hundreds.
As per the story published in Truth Stream Media “Why Have There Been More Mass Shootings Under Obama than the Four Previous Presidents Combined?”, they represented following graph:
It included the following chart, which it said was based on several data sources. One was the Mother Jones database on mass shootings, which uses the four-killed-or-more criteria. Two others were from Wikipedia.
Based on the data collected form different sources, the truth was misrepresented. Cherry picked data gives incorrect representation of data and misleads audience with the facts.
Below is the reality for number of shootings by presidential terms using only the data from the same database:
https://www.theatlas.com/charts/41Y3HT7Ux
Source: http://truthstreammedia.com/2015/12/02/why-have-there-been-more-mass-shootings-under-obama-than-the-four-previous-presidents-combined/
US Mass Shootings, 1982–2023: Data From Mother Jones’ Investigation
https://qz.com/580859/the-most-misleading-charts-of-2015-fixed/