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Old December 2, 2005, 12:19 PM   #1
FirstFreedom
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Terminology: "Accuracy" vs. "Precision" vs. "Consistency" vs. other

OK, my buddy who is a big hunter but not really that into guns in and of themselves, and I each use different terms to express the same concept.

Specifically, I refer to group size as the gun & shooter's "Accuracy" and refer to how close the group is to the bullseye as "Precision" or just "being zeroed", but technically, I believe the proper word for being zeroed refers to the rifle's 'precision'.

But what I call "precision" (how close to the bullseye), he calls "accuracy", and what I call "Accuracy" (group size), he calls "Consistency".

Now he thinks that this difference in terminology is just 6 of one, half dozen of the other, whatever floats your boat. But I, OTOH, seem to recall that my terms are actually the *correct* use of the terms in referring to accuracy & precision. Am I recalling correctly?
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Old December 2, 2005, 12:23 PM   #2
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I believe your terms are indeed correct, but just to play devil's advocate, as long as you guys know what you're talking about, who cares?
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Old December 2, 2005, 12:44 PM   #3
FirstFreedom
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Well, because it leads to confusion when we are talking about guns. I call something accurate, and he thinks "so what? I can get a shot near the bullseye too, the question is how consistent is that?", when that is precisely what I meant. I need to present him with evidence that I am correct, so that he can use the right words and eliminate confusion - he needs to get on the same page, since he owns a buttload of guns.
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Old December 2, 2005, 12:59 PM   #4
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Well, I don't know if an internet forum counts as evidence, but you have my support.
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Old December 2, 2005, 12:59 PM   #5
dave_in_delaware
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Let's start with Merriam-Webster's definitions:

Main Entry: ac·cu·ra·cy
1 : freedom from mistake or error : CORRECTNESS
2 a : conformity to truth or to a standard or model : EXACTNESS

Main Entry: pre·ci·sion
1 : the quality or state of being precise : EXACTNESS
2 a : the degree of refinement with which an operation is performed or a measurement stated

Now, this didn't really help me understand the difference, so I found an example on the internet. Here's the full story http://www.uh.edu/engines/epi1742.htm and here's the example:

Quote:
We use the two terms accurate and precise to mean quite different things. Imagine for example, two police officers on the target range. When they look at their respective targets, the first discovers a very tight grouping of hits, four inches to the left of the center. The second officer finds a random scatter of hits, eight inches in diameter, centered about the aiming point.

And so the first one's shooting is extremely precise, but it's inaccurate. The second one is quite accurate and very imprecise. The word precise actually means no more than well-defined. We save the word accurate for close-to-being-correct.

So, in the shooting realm, I think "accuracy" is talking about how close you got to the bull's-eye (your aim point). It's all about hitting exact center. You miss where you're aiming and that's called a mistake. Accuracy is freedom from mistakes.

Precision is talking about how tight your group is (degree of refinement). Consistency is close to precision then, being able to always shoot a tight group all the time.

I guess you need all 3 then to be a really good marksman.

Does that clear things up? I'm not sure if it does.
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Old December 2, 2005, 03:18 PM   #6
tINY
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Accuracy is hitting close to your target - like D in D says.

I differ on the "precision" and "consistancy" (my engineering addled mind likes to call it "repeatability").

Repeatablity would be how well you can put one bullet on top of the previous, so the smallest group size has the best repeatability.

Precision has to do with how much you move with the smallest adjustment. So, if the group on the left moved past the center and to the other side of the bulls eye with one click on the sights, it wouldn't have very good precision. Think of it like this: A rifle with a scope having 1/2moa detents is less precise than if the scope had 1/4moa detents.

So, if your repeatablity is worse than your precision, you won't be able to adjust for good accuracy as well.....

The trick is short vs long term repeatability. Long term repeatability is often called consistancy. But, there is a lot of imprecision in the english language.



-tINY's 2¢

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Old December 3, 2005, 09:04 AM   #7
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Same thing in the medical and science fields. For instance a blood gas reading may be accurate or close to the true value; however, the precision or consitency is what is most important 'cause you want to follow trends, etc.

I always remember that a precision instrument has little error while recalibration fixes accuracy.
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Old December 4, 2005, 11:12 AM   #8
raktrak
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Accuracy/Precision/repeatability/etc

HEY GUYS: Being an old Forester that has spent a life time playing in the woods, can cause one to be confused easily. If my hunting rifle will shoot 1/2 to 3/4" at 100 yards with 3 shots and will shoot 2"or less at 300 yards Im happy cause I can twist the knobs to hit dead on the bullseye. However my 6.5x55 tight neck benchrest rifle had better shoot 5 shots under .250 or I clean it. Then to confuse everything my old single shot Ruger # 1, 270 cal. must hit the bullseye at 300 yards within a 3" circle, first time out of a cold barrel. My old SWISS k-31 shot 1 1/4 inch groups at 100 yards with ball and iron sights. it now shoots 1/2 to 3/4" groups with handloads cause I put an SK scope mount and a bushnell pistol scope on the thing. To me accuracy is in the eye of the shooter. Repeatabily is if you practice, precision is knowing where your bullet is at all times in its flight and adjusting for wind and kill zone size. SHOOT STRAIT AND OFTEN.
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Old December 4, 2005, 08:15 PM   #9
Art Eatman
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Consistency, seems to me, means that the groups stay about the same size, and the point of impact doesn't change very much over the off-season.

, Art
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Old December 5, 2005, 12:38 AM   #10
siotwo
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Dave has it!

Great find on UH website..go coogs!

Dave is both accuract and precise in his reply.
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