bozo699
Gold $$ Contributor
Absolutely!….
Wayne
What causes POI to wander?
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Wayne
I downloaded Kieth's data and looked at it in relation to Loads 1 and 2 and whether or not the group locations were moving around on Load 1.
When you look at all 33 shots as a group and calculate the mean point of impact you find that LOAD 1 and Load 2 have almost the same group center and the vertical and horizontal standard deviation is extremely close and not statistically different by the F Test method. The Load 3 mean point of impact is moved horizontally and the distribution is similar to Loads 1 and 2 but now spread more vertically than horizontally. Practically Loads 1 and 2 are the same. Statistically speaking they are the same for this test.
For simplicity let's consider Loads 1 and 2. If you compare the average distance between the group POI and the 33 shot average POI it turns out that Target 1 is 100.1 with a standard deviation of 32.93 and Target 2 is 87.25 with a standard deviation of 27.87 This is based on only 7 values and when compared by Welch's T test (for mean distance) and F Test (for variance) there is no statistical difference in the offsets of the groups.
Anecdotally it appears that the Load 1 groups do appear to move but all nearly within the range of Load 2 groups. We do not have any information that can identify why the group centers move but one possibility is purely sampling and random dispersion. Was it the shooter? If Load 1 and 2 were tested again would the same pattern repeat? The answer is we do not know. What we seem to have is data indicating that Loads 1 and 2 are almost identical in mean POI and in dispersion with less vertical dispersion than Load 3.
This is a situation where 33 shots is not enough to determine if there is a difference between Loads1 and 2 mean radius or average point of impact. It is also not enough data to determine if the point of impacts for the two targets is actually different.
When you look at all 33 shots as a group and calculate the mean point of impact you find that LOAD 1 and Load 2 have almost the same group center and the vertical and horizontal standard deviation is extremely close and not statistically different by the F Test method. The Load 3 mean point of impact is moved horizontally and the distribution is similar to Loads 1 and 2 but now spread more vertically than horizontally. Practically Loads 1 and 2 are the same. Statistically speaking they are the same for this test.
For simplicity let's consider Loads 1 and 2. If you compare the average distance between the group POI and the 33 shot average POI it turns out that Target 1 is 100.1 with a standard deviation of 32.93 and Target 2 is 87.25 with a standard deviation of 27.87 This is based on only 7 values and when compared by Welch's T test (for mean distance) and F Test (for variance) there is no statistical difference in the offsets of the groups.
Anecdotally it appears that the Load 1 groups do appear to move but all nearly within the range of Load 2 groups. We do not have any information that can identify why the group centers move but one possibility is purely sampling and random dispersion. Was it the shooter? If Load 1 and 2 were tested again would the same pattern repeat? The answer is we do not know. What we seem to have is data indicating that Loads 1 and 2 are almost identical in mean POI and in dispersion with less vertical dispersion than Load 3.
This is a situation where 33 shots is not enough to determine if there is a difference between Loads1 and 2 mean radius or average point of impact. It is also not enough data to determine if the point of impacts for the two targets is actually different.
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