After an end it pays to move the sight by only part of the error you see

1 study · archers measured

Each circle is a study: its position gives the year, its row whether it is for, against or context, its size how many participants it measured. Light circles are studies on other populations or without archers.

A single paper supports it, and it is a model. The reasoning starts from a statistical point: the centre of the arrows in one end is a poor estimate of the real centre of the group, with a typical error of about 58 per cent of the group size for three arrows and 41 per cent for six, so an archer who moves the sight by the whole offset of every end is also chasing chance. In a Monte Carlo simulation of twelve ends at seventy metres, with the sight starting correct or out by half a ring, one ring or two rings, the best correction factor lies between 0.2 and 0.6, depending on skill level and the initial offset; the author suggests 0.5 in the practice ends and 0.2 or 0.3 in the scoring ends, and with an initial offset of half a ring and a factor of 0.2 the typical loss is about 1.3 points per qualification round. The rule changes for archers who know where they were aiming: for elite men in compound the author suggests a higher factor, around 0.6. No archer has yet put it to the test on the field.

Also phrased as: "don't chase every end with the sight"; "correct the sight by half"; "how far to move the sight after an end"; "adjusting the sight during competition"; "sight correction factor"

In practice

At the range some archers turn the sight by the whole offset they see after every end and others wait a few ends before touching it; the idea of always correcting, but only by part of the offset, is heard less often.

Evidence

2020
Context Model Published later

The statistical point the rule starts from: the standard deviation of the estimate of the group centre is that of the group divided by the square root of the number of arrows, so with the three arrows of a match end the centre of the end lies on average about 58 per cent of the group size away from the real centre, and with the six arrows of a qualification end 41 per cent. More arrows give a better estimate, but waiting for 36 or 72 arrows before correcting would cost points: that is why, the author writes, it is easy to see after a round that the sight was out and hard to see while shooting.

The impact of off-centred groups on an archer’s score · James L Park
2020
For Model Published later

A Monte Carlo simulation of a twelve-end qualification round at 70 m on the 122 cm face, for archers at skill levels (ASL) of 130, 110 and 90, with the sight starting correct or off by 30.5, 61 or 122 mm (half a ring, one ring or two rings). With a correction factor of zero the error stays at its starting value, and with a factor of one the archer chases the offset of every end; the minimum, which is flat, falls between 0.2 and 0.6 depending on skill level and the initial offset. The author suggests 0.5 in the practice ends and 0.2 or 0.3 in the scoring ends; with an initial offset of half a ring and a factor of 0.2 the typical loss is about 1.3 points per round, less than the archers at the events analysed were losing, except the elite men in compound. For them, since they know where they were aiming when the release went, he suggests a higher factor of about 0.6. The model assumes a stable group and a sight that moves precisely: the smallest click of the adjusting screw, for example 6.5 mm at 50 m on the author's compound, puts a limit on small corrections.

The impact of off-centred groups on an archer’s score · James L Park

Status history

1990 Not studied Nobody in the registry's bibliography has yet calculated how far it pays to move the sight after each end.
2020 Transferred A paper on off-centre groups asks the question and answers it with a model. With three or six arrows the centre of an end is a poor estimate of the real centre of the group: the typical error is about 58 per cent of the group size for three arrows and 41 per cent for six. A Monte Carlo simulation of twelve ends at seventy metres concludes that it pays to correct the sight by only part of each end's offset, with a best factor between 0.2 and 0.6 depending on skill level and the initial offset: about 0.5 in the practice ends and 0.2 or 0.3 in the scoring ends. It is a model, with no archers to test it: transferred.

Related studies

Theoretical workIl pavimento (The floor): how much of archery is real

Research lines

Where there are no studies on archers, every decision starts from a written hypothesis and is checked against the data over time.

See the full assessment

Cite

APA

Campagna, M. (2026). After an end it pays to move the sight by only part of the error you see (Version 1). In Evidence Registry. Retrieved 16 October 2026, from https://matteocampagna.com/en/registry/competition/partial-sight-correction

BibTeX

@misc{campagna2026_correzionemirinoparziale,
  author = {Campagna, Matteo},
  title = {After an end it pays to move the sight by only part of the error you see},
  year = {2026},
  howpublished = {Evidence Registry, matteocampagna.com},
  url = {https://matteocampagna.com/en/registry/competition/partial-sight-correction},
  note = {Version 1; accessed 2026-10-16}
}

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