Talk:Accuracy and precision

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Accuracy = (trueness, precision) reloaded[edit]

Hi. Please someone add a source/reference for the first given definition of accuracy. It might be an outdated one, but if there is no source at all, I might be tempted to delete it, as for the second definition there IS a source (the VIM) which would be then the accepted and (only) valid one. --Cms metrology (talk) 18:29, 10 May 2017 (UTC)[reply]

While I accept the importance of metrology, much of this Talk discussion seems — to me and probably to the vast bulk of Wikipedia users — to be perpetual wrangling over a sort of "how wet is water?" disagreement.

A working definition is needed here. Consider the "target" metaphor (whether pistols or archery or golf or whatever), where multiple attempts are made to hit some small point. (See the Shot grouping article.) Accuracy describes how close the attempts (whether the group or the individual tries) are to the center. Precision describes how close the attempts are to each other, the "tightness" of the grouping.

Having tolerated (as a line worker) multiple ISO audits, I am not a fan of ISO and blame their self-serving meddling for confusion here. (See the German WP article Korinthenkacker.) It was ISO that messed up the definition of "accuracy" then came up with trueness as another term for what anyone else (not paid meddlers) calls accuracy. So, my suggestion would be to provide brief differentiation between the two original terms, then put in a section called According to ISO or similar.

Common usage has eroded the value of the distinction, which ought be maintained. For example, individual instances can be said to be "accurate" in achieving a goal/target, but as "precision" refers to a grouping that term cannot properly be applied to one isolated attempt.
Weeb Dingle (talk) 15:34, 20 October 2018 (UTC)[reply]

Clarification needed[edit]

In science there is a clear distinction between accuracy and precision.

Accuracy is a measure of the magnitude of systematic error in the value of a measurement.
Precision is a measure of the magnitude of random error in the value of a measurement.

In the real world, measurements are affected by both types of error. Measuring instruments are calibrated for accuracy and graduated for precision. Both accuracy and precision for a quantity derived from measurements can be obtained by using error propagation methods. Petergans (talk) 14:12, 4 August 2019 (UTC)[reply]

What do you mean "in science"? I do science and most often we just talk about accuracy. Clearly, we are interested in both systematic and random error. Exactly because in the "real world" the errors are both systematic and random...and science describes the real world — Preceding unsigned comment added by 82.130.95.205 (talk) 08:40, 18 November 2019 (UTC)[reply]

Urgent to edit: there are NOT two different definitions of accuracy.[edit]

Wikipedia is great because it spreads knowledge. With this article it is just spreading the confusion! I will edit it as soon as I can, but first I'd like to keep up the discussion. Excerpt from the Wikipedia Accuracy and precision "Common technical definition": "In the fields of science and engineering, the accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's true value.[1] The precision of a measurement system, related to reproducibility and repeatability, is the degree to which repeated measurements under unchanged conditions show the same results.[1][2] Although the two words precision and accuracy can be synonymous in colloquial use, they are deliberately contrasted in the context of the scientific method. "

There is no contrast. When you say "the accuracy is the degree of closeness to the true value" this includes BOTH the average value (describing the trueness) AND the random errors (associated with the precision). Let's say my repeated measurements have an average value that is close to the true value. We can use the example of the darts. Let's say I shoot 100 darts and they spread homogeneously on the entire target circle. Let's say the average value is zero. Can I say that the shoots are accurate? NO! Because none of the darts are "close to the true value" (which is the center in this simplified example). The definition of precision is correct, though. It only refers to how close all my shoots are to each other, not to the true value. So If my 100 shoots all end up in the exact same point I have a high precision. But if this point is not the center, my accuracy is still low. This is exactly according to the definition of BOTH the ISO 5725-1 and the JCGM2008. An article worth reading: https://www.researchgate.net/publication/226202473_Understanding_the_meaning_of_accuracy_trueness_and_precision (disclaimer: I'm not on of the authors nor I'm anyhow affiliated with the authors)

It is sometimes easy to confuse the two terms precision and accuracy: if the bias (linked to the trueness) of the measurement is zero the only contribution to accuracy is given by the precision. In other terms accuracy = bias + precision. If bias is zero then accuracy = precision. 82.130.95.205 (talk) 10:26, 18 November 2019 (UTC)[reply]

Clarification for the content of the first line[edit]

I think the first words of the article should be ″In a set of measurements″ instead of ″In measurement of a set″. I must be mistaken. I have not studied advanced topics. — Preceding unsigned comment added by 2402:4000:2280:B5C1:A8BD:B307:5034:8F4B (talk) 09:10, 15 November 2020 (UTC)[reply]

Too technical[edit]

I added Template:Technical to the article. An example of overly technical language occurs in the first sentence of the article: "In measurement of a set ...." I would guesstimate that over 95% of readers do not know what that means. See Wikipedia:Make technical articles understandable for some helpful guidelines and suggestions. I'll try to work on making the article less technical too. Mark D Worthen PsyD (talk) [he/his/him] 22:55, 8 February 2021 (UTC)[reply]

Missing citations[edit]

This page is prescriptive and lacks citations. For example, the section titled "Common technical definition" has 6-7 paragraphs with no citations, reflecting someone's opinion as opposed to a well sourced scientific position. This is misleading and needs to be clarified, removed, or tagged. I propose tagging this section as "lacking citations" until the issue is resolved.

For example, there's a line saying "The terminology is also applied to indirect measurements—that is, values obtained by a computational procedure from observed data." What does "indirect" or "computation procedure" mean here? Are we talking about a state estimation problem, where the state cannot be directly observed? What is the role of observability in such cases? 2600:1700:3EC2:B000:ADCB:15F7:FDAF:89D (talk) 16:40, 19 June 2023 (UTC)[reply]