The goal of self defense is to stop the threat.
I heard tell of a study that said 90% of attackers when shot with any caliber (including a .22) stopped their attack, not wanting to be shot a second time!
Anyone ever read such an article?
Yeah, it was actually widely publicized at the time, and has come up regularly ever since, so I'm honestly surprised you didn't at least hear about it until now.
Google; "An alternative look at handgun stopping power" for starters. There were a few others like it, but that's the first one that comes to mind.
That being said, like most conclusions based upon statistics, the results are hopelessly skewed due to the sheer numbers of popular cartridges, ergo it ranks .22LR & .32 ACP the highest in terms of successfully stopping a threat among handguns, and ranks .380 ACP as equal to .357 Magnum, but that's most likely because pretty much everyone owns a .22 pistol and .380 ACP has seen a huge resurgence in popularity since the release of the Kel-Tec P3AT.
It also concludes that a double tap from pretty much everything will stop a threat like 88% of the time.
However, it does go to show that the vast majority of people do not enjoy being shot by anything and that bullets in general are potentially lethal, so contrary to what some folks insist, being on drugs does not in fact make 100% of addicts into fearless killing machines who have absolutely no problem with being shot.