Well the number of people shot doesn't matter because how effective a round is must be determined on a target by target basis.
The number of hits doesn't matter because we don't know how many shots were fired in the first place AND we are evaluating the round not the shooter. Accuracy is the responsibility of the shooter not the round. If they can't hit with it then they need to find a round and more importantly a gun that they can hit with... but, again, that is neither here nor there.
Percent of hits that were fatal don't matter because we don't know the exact path said "hits" took through the target. We don't know which parts of the body these "hits" struck, we don't know which organs were penetrated, and we don't know how much damage was dealt to the organs that were hit.
Average number of rounds until incapacitation doesn't matter because we don't know if that means number of rounds fired or number of hits and we don't know where those hits struck in the first place.
One shot stop percent doesn't matter because it depends upon how drugged up/unafraid the target is and doesn't tell us why it took only one shot to stop them. They could have gotten shot once through their arm and given up or they could have been shot in the medulla oblongata, severing the body's connection to the brain instantly.
Accuracy doesn't matter because it is the shooter's responsibility to hit not the round. And, they only count torso/head hits? They don't count the shoulder, arm, hand, foot, pelvis (which can render a person incapable of walking), etc.
% actually incapacitated by one shot (torso or head hit) doesn't matter because it doesn't matter how many were stopped with one shot but WHY they were stopped with one shot.
Guy1, "My machete stopped him with one swipe!" Guy2, "Why? Did you chop his head off?" Guy1, "No, I slashed his carotid artery and he bled out."
Here is an idea for an actual study if someone wants to actually do one.
Caliber: (rather self-explanatory)
Firearm: (including brand, model, barrel length, action type)
Bullet specifications: (including manufacturer, bullet weight, etc. etc.)
Number of hits: This is where you put a legitimate description of exactly how many hits were scored on the bad guy and a detailed description of each one of those round's paths through the bad guys body (taking care to note which organs in the body were affected and to what extent they were affected). It is also important to give a detailed description of the target's body composition.
Time until incapacitation: As accurately as possible note the time from the first hit until the bad guy was incapacitated. "Incapacitated" for the sake of this study will mean, "incapable of posing a threat." If they give up or are unwilling to continue fighting that does not count and will invalidate that incident. Why? For example, if that person was on drugs or possessed a stronger will/determination/motivation the incident would not have ended at that point in time.
I wager that no one will ever collect this data. I doubt someone will be able to convince medical staff around the globe to so intimitely record the path and damage inflicted by every single bullet that penetrated a body. And, they might not even be able to tell the caliber of the bullet(s) if the bullet(s) is(are) even recovered at all.
I also doubt you will be able to discover the exact moment the target took the first hit let alone WHICH hit is the first hit.
So I think everyone should just stick to what we know, which is very little, but enough in my opinion. If you pierce the heart we can safely assume appropriate blood flow throughout the body will have been disrupted and the resulting bleed out/lack of oxygen to the vital organs will incapacitate the target in the prescribed amount of time (easy to consult a medical professional on how long all of that takes). We can also safely assume that if we detroy the parts of the brain that permit motor function and/or render the brain incapable of communicating with the rest of the body the target will be considered instantly incapacitated. So if your favorite round can make it through a person's heart and through a person's skull and still destroy vital parts of the brain (located closest to the back of the head near the base of the skull around the medulla oblongata and the medulla oblongata itself) then you have a perfectly lethal round. If that hole is .1" bigger it doesn't matter because destroyed is destroyed and stopped is stopped.