I always forget to bring this up in caliber debates. Greg Ellefritz’s study on handgun stopping power (the whole thread has similar info to this one). The link below has a Youtube video which helps explain the data and the article.
The bottom line is almost all handgun duty calibers required about the same numbers of shots “to stop” the threat. Which is almost 2 shots on average. If you want a “one shot stop” you need a rifle or even better a shotgun.