Riiight. Nope, no bias in that study at all. Refer to my link above about the murder rate of states vs. gun ownership.
And I am completely sure that there is no bias in that study that you linked... none at all.
Guns are used about 800,000 times per year in America to prevent crime.
https://en.wikipedia.org/wiki/...
So, explain to me why the gun usage, as a percentage of homicide rate, did not actually drop significantly? Could it be that the HONEST people were the ones that gave up their guns while the criminals kept theirs?
Also, is mass shooting the ONLY way to measure success? What if you went back in time, prevented the gun laws from passing, and found that 20 more people died per year in mass shootings, while an extra 100 or so were killed individually? Is it somehow worse when people die as a group but not so bad when they die one-by-one?