https://matteocampagna.com/en/registry/competition/arrow-group-from-a-photograph Changes to this claim in Matteo Campagna's evidence registry: its status, its year-by-year history, revisions of the page. en-gb https://matteocampagna.com/en/registry/competition/arrow-group-from-a-photographThere is only one study, from 2012, and it uses neither archers nor coaches but ten people with no shooting experience. An archer shoots 72 arrows at 70 metres, every end is photographed and every hole measured to the millimetre; the ten operators then mark the arrows from the photographs on a target face drawn on a computer. Correlations with the measured positions exceed 0.977 and those between one operator and another 0.969, and of 720 arrows marked only four change score. The mean error on each axis is about 1.1 per cent of the target radius, around seven millimetres, and it is almost entirely random, so it cancels out in the average of the group more than on the single arrow. That is why, among the indices calculated from the group, the position of the centre suffers little (0.57 per cent error) and the size more (1.53 per cent on the mean radius). The method works without any knowledge of archery, and fits within the four minutes of a qualification end. What is missing is a test with the people who would actually use it, archers and coaches, on photographs taken in competition: that is why the status is transferred.claim:rosata-da-fotografia:revision:2026-07-04:2Sat, 04 Jul 2026 08:00:00 GMT https://matteocampagna.com/en/registry/competition/arrow-group-from-a-photographclaim:rosata-da-fotografia:new_claim:2026-06-19:trasferitoFri, 19 Jun 2026 08:00:00 GMT