I know from hunting that you can shoot two of the same type of animal in very similar places and come out with different results. I also know that in human examples, what is or is not fatal is often the result of what medical treatment was received and how quickly. I know of a lot of one shot stops with various calibers that were non-fatal, non-incapacitating, and a few that didn't even hit the bad guy. Psychological stops are great when they happen, and they do happen, but are not very predictable.
A lot of these shot percentages are thrown out there like they mean something. However, virtually no two people are ever shot exactly the same way. Shot distances, angles, circumstance, bullet types, velocities, etc. are often quite varied. You can find accounts of people shot in the heart that survived, the survivors being fatally shot, had they not gotten the correct care fast enough. As such, they are not in the fatal category, which is really interesting. After all, how can caliber take into consideration the speed and skill of subsequent medical care? Many people may become incapacitated by a single shot, but is the incapacitation instant, quick, or maybe minutes or hours later.
The numbers are just a mathematical derivatives of generalized categories that fail to take in a lot of very relevant factors that influence the success of the impact of the shot on the intended target. As such, while the resultant numbers appear very precise and are heuristically interesting, they are also false precision. No doubt this is why the .32 appears to be a wonder caliber occupying a magical synergistic crossroads of a comparatively smaller caliber, lighter weight, reduced energy, moderate velocity, reduced to moderate penetration, etc.
