Statistical anomaly checks
Figures unusually far from comparable records: a barrel half the length of its family's, a weight twice that of every other gun of its category, cartridge and action, a barrel an odd share of its gun's length. Unusual is not wrong. A shortened carbine, a magnum chambering or a heavier target build is unusual and right, so a finding here is a figure to verify against a source: a low priority review task, closed by a correction or by a confirmation, and a confirmed figure is not raised again.
What it asks
A figure against its family: every record filed as a variant of one gun is compared with its family's median on barrel, length, weight, velocity, energy, capacity, trigger pull and rate of fire. Velocity and energy are compared only among members that share a cartridge.
A figure against its cohort: barrel, length, weight, velocity and energy are compared with guns of the same category, primary cartridge and action. Capacity, trigger pull and rate of fire vary too much between models to compare this way.
Barrel against length: a barrel's share of its gun's overall length is compared with guns of the same category and action. A share far off usually means one of the two figures belongs to another configuration, such as a folded stock or a barrel measured with its muzzle device.
What a record already explains is not raised: a bullpup short for its kind, a gun built around its suppressor, a variant whose name or type says it is a compact, a carbine or a long target model, an air gun set to a country's power limit, a figure a person has verified, and a gun unusual on two related figures in the same direction.
How it is calculated
A figure is scored by how far its logarithm sits from its group's median, counted in spreads of the group itself. Past the cut, and at least half as large again as the median or two thirds of it, the figure is unusual: one to verify, not one shown wrong. A real family worked through:
Answer: 780 mm is past 705 mm, a score of 4.29 at 1.73 times the median, so the barrel is unusual for its family and is raised for review.
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What happens to a finding
- Every run is published here as it happened, failures included, before anyone has looked at it.
- Each run is also kept as a report that lists what was fixed since the run before, what is new and what is still open, so progress is measured finding by finding rather than claimed.
- No check edits the catalogue. A finding goes to a person, who corrects the record by hand and cites what the correction rests on; the next run confirms it.
- A check id is never renamed, so a link to one keeps meaning the same question.