Basing this theory of effectiveness on a mathematical formula based on statistics and assumptions is all fantasy warrior-ship.
The formula/calculations have no bearing on effectiveness in the sense of predicting a person's success in an actual gunfight.
There's really no way to take the results and turn them into some way of predicting how well someone will do in a gunfight the real world. That's because success for the purpose of the calculations is defined as making a certain number of hits and we all know that it takes more than simply making a certain predefined number of hits to insure success in a real-world gunfight.
What the charts effectively do is tell the probability that a defender will make 4 or more hits with a given hit rate probability and a given number of rounds available. They will provide that information reliably and accurately.