For one example, the M&S (Marshall & Sanow – ed) study measures instances of “One Shot Stops”. Fine. Fair. But they don’t go on to qualify this measure. “One Shot Stop”, as a name, doesn’t offer any information regarding WHY the person stopped; i.e. the difference between a “physical stop” (the person is physically/mechanically disabled and cannot continue the attack) and a “psychological stop” (person undergoes the “I Just Got SHOT!” reaction and subconsciously DECIDES to stop the attack themselves). Without taking the time and care to qualify what parameters you use to define the Primary Measurement used in your study, anything you derive from that measurement is going to be inaccurate.
In conclusion, reading the M&S study is like working under a car with a child fetching your tools. What you really need is a 3/4″ socket. When the kid shows up with a handful of screwdrivers, you have to thank him for trying, but you still can’t use any of those to fit the task at hand; and you’re really no closer to tightening that bolt. What you really need now is someone who knows what that tool looks like, and knows how to get it to you.
From this thread at The Firing Line. Most of it is pretty bad, because it’s full of people who believe that the Marshal and Sanow study was something other than total nonsense. The guy that wrote the post I linked to though is pretty squared away.
Remember, the one-shot-stop is a myth. The most effective way to incapacitate an attacker when using a pistol is multiple rapid hits to the thoracic cavity, and even then that’s no guarantee. Your gun isn’t a deathray, whether it’s a 9mm, a .40, or a .45 ACP.