This is a discussion on Testing probability with the Sig P250fs - with shooting pics of course! within the Defensive Carry Guns forums, part of the Defensive Carry Discussions category; This is to address an issue I wasn't sure came out clearly in the thread, “The more you shoot, the worse it gets” , and ...
This is to address an issue I wasn't sure came out clearly in the thread, “The more you shoot, the worse it gets”, and the targets I posted in that thread were a bit misleading.
It's not that I shot them incorrectly; it's that the cumulative spread, or group size, of the three shot targets, appeared to be a bit smaller than the 9 on 1 target. Statistically speaking they should reflect smaller group sizes for fewer shots, but nearly identical accuracy.
How probability sees this is the probability of getting one hit raised to the power of the number of attempts. So say I have a 0.9 (90%) probability. I would have a probability of 0.9^9 = 38.7% of getting 9 hits in 9 tries.
The probability of getting 3 hits in 3 tries is 0.9^3 = 73% which looks a whole lot more favorable than 38.7%. But I'm trying to do that 3 times, so I have to calculate, 0.73^3 = 38.7%, exactly the same as 9 for 9.
The following pics are more indicative of what probability predicts. I shot 2 shots on 5 targets and 10 shots on 1 target and then repeated that with a new 'stick-on" (target), to keep the hits separate.
Here’s the details:
Targets: 2" dia. Shoot-N-C stick-ons on a reverse color B27 target as a backer
Range: 7 yards
Gun: P250fs with a small grip (very much like an E2 grip) with my P250 compact's FCU
Shooting method: All shots are off-hand in a 'I' stance.
Shooter’s Depot indoor range
A couple of things to note. The top target of the 10 on 1 has to be an anomaly. The first shot, upper left, of the top target was a sighting problem and I knew it as soon as I shot it. The 2 off at the bottom of the top target are not especially typical, but reasonable.
Then on the 5th two shot target, the miss at the top of the bottom stick-on was the last shot of the test, and my mind was pretty much fatigued. I'm not sure I should have even shot the second group, but I knew the first 10 on 1 wasn't typical and figured I needed to reshoot it and if I reshot it, to be consistent I felt I should reshoot the other five again too..
Here's the 10 on 1 target. The top stick-on was the first target shot; the lower was shot in the second evolution between the 2nd and 3rd two shot targets just to change the order.
This is #1 2 on 1
This is #2 20 on 1:
This is #3 2 on 1:\
This is #4 2 on 1
And this is the fifth 2 0 1
There is no question that the individual group size of the 2 shot targets are significantly smaller than the 10 shot targets. Even that 40th shot that missed the fifth target, still has a slightly smaller group than the better 10 shot group and that particular 2 shot target was both atypical and right at the edge of fatigue.
It should also be noted, that if you imagine all the 2 shot targets superimposed, centered on the center of the stick-on, the cumulative group size would be just about the same as the 10 shot group.
So the conclusion is our shooting does comply with probability, it's just that we're not ALWAYS probable and some may be more probable than others
I'm too young to be this old!
Getting old isn't good for you!