When it comes to gun massacres, there are more public mass shootings in the United States than in any other country in the world, according to a new study.

Between 1966 and 2012, there were 90 mass shootings in the United States, where there is nearly one firearm for every American.

The 90 mass shootings in the country are nearly a third of the 292 such attacks globally for that period. While the US has five per cent of the world's population, it had 31 per cent of all public mass shootings.

Mass shootings are defined for the study as having four or more victims and don't include gang killings or slayings that involve the death of multiple family members.

"People have been a little surprised by these statistics," CNN quoted Adam Lankford, an associate professor of criminal justice at the University of Alabama, who did the analysis.

Lankford presented his work at the American Sociological Association's annual conference last weekend and says it's the first research of its kind to do a global comparison.

Lankford combed through the records of every incident and found a few common factors that set the US incidents apart from the rest of the world's.

In the US, people have a greater chance of dying in mass shootings if they are at work or at school. Overseas, these incidents typically happen near military installations.