Confusion between "Exactitude" and "Precision"

Question

Exactitude and precision are usually treated as synonyms. At least that is what I found upon performing the query for the spanish translation of the word "exactitud".

However, in a strict sense these two words carry different concepts.

In Measurement and Instrumentation technology the term "exactitude" stands for the capability of an instrument for rendering the real magnitude of a physical variable; i.e. a more exact instrument displays a reading which more closely reflects the true value.

In contrast, "precision" refers to the capability of this same instrument for repeatedly displaying a reading with a given exactitude.

Hence the question: Why do dictionaries resort to posting these two words as interchangeable being that in a strict sense they are not?

Answer 1

Hence the question: Why do dictionaries resort to posting these two words as interchangeable being that in a strict sense they are not?

I completely agree with you, but most of people do not make this distinction. You have to have some technical or engineering knowledge to make it.

I guess those who compile the dictionaries usually don't have it.

Answer 2

Blockquote: " 'precision' doesn't refer to "repeatedly displaying a reading with a given exactitude"; rather, it reflects the "resolution" or "granularity" of the measurement: in other words, to how many decimal places something is measured ".

In Instrumentation technology, exactitude, precision and resolution are three separate, non-interchangeable terms which carry their own particular concept. The wording regarding the definition associated to each term may be readily found in specialized references and textbooks:

• Exactitude: Ability to display a reading as close as possible to the true value.
• Precision: Ability to repeatedly display a reading with a given exactitude.
• Resolution: The smallest possible detectable difference in a reading.

Hence, the definition for resolution, as quoted above, is the correct one. However, it does not at all relate with precision. At least it does not when taking the technological focus into consideration.

In striving to keep it as simple as possible, the original question does not contain a reference to "resolution" and only gives treatment to the "exactitude" vs. "precision" quandary:

Dictionaries tend to use precision for defining exactitude quite loosely; resolution not being mentioned at all. Why do dictionaries (even the best ones) neglect the information already available in specialized texts?

Answer 3

I'll just talk about English here. When I look in my Chambers's Technical Dictionary (3rd ed.), I don't see either term listed. Less technically, in my American Heritage Dictionary, I see three definitions for the adjective 'exact' and six for 'precise'. Conventional dictionaries generally reflect the shades of meanings of popular usage and may provide mere guidance in variations in meaning and sometimes just synonyms, which are rarely semantically identical. Without the rigor of, e.g., a detailed genus-differentia definition, you may not be able to rely on regular dictionaries for your purposes. I rarely use the word 'exactitude', but I do use 'exactly' to contrast with 'approximately'. To me, 'precision' doesn't refer to "repeatedly displaying a reading with a given exactitude"; rather, it reflects the "resolution" or "granularity" of the measurement: in other words, to how many decimal places something is measured. I refer to the repeated or consistent aspect as 'reliability'. Finally, I use 'accuracy' to refer to the true value. Bilingual dictionaries are going to be even less helpful for scientific or engineering purposes, and I've never seen a technical bilingual dictionary.

Answer 4

And most engineers and scientists would use precision and accuracy for the above concepts, whereas I have never seen 'reliability' used in an even vaguely related way.

There are plenty bilingual technical dictionaries (I own several, those most are English/German) but could really use a good Spanish one. At some point, by the time most people are going to need the precision in terminology, they're working in the language itself, and don't need a foreign/native version of the dictionary. I had one engineering and one language prof each in Germany that wouldn't even let us use bilingual dictionaries. Only the same regular and technical dictionaries that natives used. Slowed us down initially, but made us much stronger longer term. They did us a big favor, even if I cursed it at the time.

In closing, I'll say two things. Most technical people when contrasting the original concepts, will use the term accuracy instead of exactitude.

Most lay people would be far more likely to use the word precision than exactitude. The latter is not a super common word in most fields.

hth roger

Answer 5

It can be synonymous , but it is not always exclusive. It is based on context. You are using just one context.

We can estimate terminal velocity of an object with great exactitude/precision.

That's exactly the point. In Engineering, the estimate for a velocity can be performed with great exactitude. But that does not necessarily relate to precision, although a measuring instrument can precisely display the value. - burst3, Aug 10, 2012

DIctionarys cover a broad context, you are using a singular context, Webster's Precision the degree of refinement with which an "operation is performed" or a measurement stated. To infer that they can never be synononymous would not be accurate. ;) - amaken, Aug 11, 2012

Oops! Should be "Dictionaries". I shouldn't use my phone for this. - amaken, Aug 11, 2012

Answer 6

Here is a watered down non engineering example......

Multitude and Masses