The software can:
- Load images (e.g. scans) of targets with impacts
- Point-and-click to mark the scale (some known length on the target)
- Point-and-click to mark the target centre (point of aim, POA); understands multiple targets/groups on the same image
- Point-and-click to mark all impacts
- For individual groups, calculate extreme spread and average point of impact (POI) -- nothing else. We could do much more, but this is pointless -- see below
The actual evaluation of rifle precision is NOT done by groups' extreme spread, but by individual impacts aggregated from all targets. This, for several reasons:
- The number of shots in a single group is, as a rule, statistically insignificant, and
- Measuring precision by extreme spread is probably the LEAST efficient way of doing it, in terms of information per shot (we are using only two points of data; of the rest we only know that it is somewhere in between). Evaluating precision from all individual shots in a series saves you 25% to 40% of ammo to get to the same confidence.
- Also, extreme spread is very much skewed by fliers; a single flier in 5 groups of 5 shots skews 20% of measurements. A single flier in 25 individual shots skews only 4% of data.
Over all data points, the software calculates the statistically valid measure of spread -- sigma, R50, R95, etc. along with associated confidence margins -- the more shots we shoot, the closer we get to the truth (Rayleigh estimator and associated confidence intervals). It also calculates the aggregate average POI (with associated confidence margin) -- how much off is your zero.
Incidentally, for entertainment purposes, the software also calculates average 5-shot and 10-shot groups size that can be expected from the rifle.
But a picture is worth approximately 417.6KB words. Behold the screenshots.