A shock 2016 study argued that the U.S. accounted for nearly one-third of all mass shootings, sparking global headlines about the dangers of an American gun culture. Now another researcher says the original study “botched” the data. John R. Lott Jr., president of the Crime Prevention Research Center, crunched the numbers and said his count shows that the U.S. had less than 3 percent of the world’s mass public shootings over a 15-year period.