Accuracy and Precision - yet again

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mikemyers

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This thread has more to do with understanding and/or evaluating shooting, than actual shooting. If you're not interested in that sort of thing, it will probably seem very dull and boring. In my case, I'm tired of getting my mords wixed up, so maybe after a few responses, I'll have a better understanding of things...


Every time I think I know what "accuracy" and "precision" mean, I end up reading something that makes me wonder if I'm really using the terms correctly. Instead of asking the usual questions, what is accuracy, and what is precision, maybe I'll understand better if someone can explain it in reverse.

You are asked to analyze the accuracy and precision of a target that has already been shot at. It has the concentric rings for scoring, and a dozen or so bullet holes in it. You don't know anything about the conditions under which it was shot, what kind of gun was used, slow-fire or rapid-fire, or anything else - all you have to go on is the target.

Question:
  • Can you say anything about the "accuracy" and the "precision" with nothing more to go by, than the target? If so, how would you figure out how the positions of the holes might indicate better/worse accuracy and precision?
  • If only the above information is not enough to allow you to comment on the accuracy and precision, what else might you need to know?


This thread is all about accuracy and precision, so feel free to bring up anything I didn't think of, that needs to be added. For example:
  1. If accuracy and precision are a function of the target, then the target is all you need to have, to comment on both.
  2. If accuracy and precision are a function of what the shooter was trying to do (self defense, target shooting, speed contest, gun testing) then more information might be required?
  3. If accuracy and precision are a comparison with other people, or past/future shooting ability, then more targets need to be evaluated to give an answer?
  4. If accuracy and precision are needed as part of a gun review, then even more information is needed before being able to comment on this particular target?
  5. Were all these shots fired one at a time, or if the shooter loaded many more shots, and reloaded as needed so he could quickly go through the dozen shots??
  6. Probably lots more things I haven't thought of........
 
I have yet to read an explanation/explication of the difference in usage that makes me think the words need to be differentiated in the context of shooting. I understand what the semantic claims are, I just don't see what functional communicative objective is furthered by insisting upon them.
 
There are too many variables left out if all you have is the target. For instance assuming a standard SR-1 rifle bullseye (12" aiming black), that has a bunch of holes all in the black. Say an 8" group with 10 shots.

If that was shot with a rifle slow fire off hand at 200 yards (standing un-supported) that's decent shooting (not match winning but certainly not bad). If it was fired from the prone at 50 yards slow fire, that's fairly poor shooting (or a brand new shooter). If it was fired at 600 yards slow fire prone, then that's pretty good shooting (barely over 1 MOA).

If it was shot with a pistol at 7 yds from the holster in under 3 or 4 seconds, that's pretty good shooting. If it was shot with a pistol at 25 yards, slow fire with a tuned 1911 or PPC gun designed for shooting bullseye, that's not great shooting, but not horrible either. If it was shot at 7yds slow fire with a common service pistol that's not good shooting. If it was shot at 50 yards slow fire with a service pistol that's pretty reasonable shooting.

In general the smaller the group (ie minimal CEP) and the more centered on the scoring area, the better overall the group is regardless of the circumstances. However this isn't always the case. If I was looking at a benchrest rifle shooters target, I'd know not to worry about the PoA/PoI offset as that's not a scoring factor and often times deliberate. As was discussed in your other thread, if the PoA/PoI offset is deliberate, or can easily be adjusted for with the sights then it's not really a factor. If it's done due to poor marksmanship habits then it indicates a problem. A shooter who shoots a 3" group at 10 yards slow fire with a pistol is not a bad shooter. If their group is 3"-4" left, and low then I'd be inclined to believe they have some recoil anticipation issues compared to the same group being centered. However if I know that the shooter is holding at the top of the bull and still putting their rounds low and left (into the center of the bull) then it's the same problem.

-Jenrick
 
Accuracy is all about error; precision is all about repeatability.

Can you say anything about the "accuracy" and the "precision" with nothing more to go by, than the target?
Technically, no. If you knew how many rounds were fired, and you knew where each one hit the target, you could determine the precision (often evaluated as maximum group spread). If you knew the exact point on the target where the gun was aimed, you could determine the accuracy of each shot fired. If you knew both those things, you could determine the average accuracy as well.

If so, how would you figure out how the positions of the holes might indicate better/worse accuracy and precision?
Roughly speaking and not using dimensional terms, the precision is how tight the group is. Many shooters determine the approximate center of the group to determine the average accuracy of the shots.

Wind conditions will affect accuracy. Variable wind conditions can also affect apparent precision since it can pull the bullet varying amounts and sometimes in different directions.

Guns that shoot larger groups have lower precision. That means that shots will have varying accuracies.

Guns that shoot large groups, just might shoot a round exactly where it was aimed. That one shot was indeed perfectly accurate. Guns that shoot several bullets into one hole that is not where it was aimed are very precise, but are (to some degree) inaccurate. Guns that shoot several rounds into one hole exactly where the gun was aimed are precise and accurate.

Does that help to see the difference between accuracy and precision?

Lou
 
In examining just the target, you can only make conclusions involving the entire action. If all of the bullet holes appear in the same location on the target, you can claim high precision. If the group center is the same as the center of the target, you can claim high accuracy. You cannot claim that the gun is precise or accurate. Neither can you claim the shooter is accurate, nor the ammunition, nor the environment al conditions. You can only claim that the end result was precise and/or accurate.

In this exercise, we are not examining the contributing parts of the event: shooter, ammunition, firearm and environment. You can only say that all four parts contributed to the end result.

In general, precision is a measure of the ability to repeat an action and get similar results. Accuracy is a measure of the ability to achieve a specific result.
 
In regard to a firearm, I would say that precision refers to how well it is made, that is, how close it comes to the specifications for that model.

Accuracy refers to how well a firearm shoots, how close a group of shots comes to the diameter of a bullet of that caliber. How close that comes to the point of aim is a matter of sight adjustment, not firearm accuracy.

Given the many variables involved, a precision firearm might not be an accurate firearm.

Jim
 
Here is a sample target showing accuracy vs. precision. This sums it up in a straightforward manor for me.

A rose by any other name, etc., etc,
 

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This sort of thing makes thrilling Internet Pedantic Discussion, but I don't think I have ever heard the word "precision" on a shooting range.

Neither have I been called upon to evaluate a target without knowing the circumstances under which it was shot and the objective of the exercise.
I recently found a target with some bullet holes in it. It was obviously something I thought worth bringing home instead of dropping in the range trash. But not worth writing the particulars on, so I have no idea what it signified.
 
This sort of thing makes thrilling Internet Pedantic Discussion, but I don't think I have ever heard the word "precision" on a shooting range.

Neither have I been called upon to evaluate a target without knowing the circumstances under which it was shot and the objective of the exercise.
I recently found a target with some bullet holes in it. It was obviously something I thought worth bringing home instead of dropping in the range trash. But not worth writing the particulars on, so I have no idea what it signified.
You should hear the discussions among the bench rest shooters at our club. I doubt that more than two sentences go by without the term precision coming in.

Most of these guys shoot 6mm of some ilk; some 6mm BR, some a wildcat load. They measure powder in .1's grains, bullets sorted by weight, brass meticulously sized and neck turned, data on primers, etc. The previous are the paradigm of precision.

Their rifles are very precisely built. Stocks, scopes, barrels, actions, triggers, and the bench rests themselves are all precisely built. They also dope wind conditions and temperature, and they sometimes bring their hand loads to matches in coolers.

When they turn in groups measured in millimeters, center-to-center, I would call that precision shooting.

Anal retentive? Some would think so, but these guys really take precision to another level.
 
Strangely enough, I've heard the two terms used a number of times on the archery range. Consistently doing the same motions is a goal, to have all your arrows fly and land at the same point. We call this "precise" shooting. We adjust our aim to improve "accuracy".
 
The target described in the first post will give you little to no info on the accuracy or precision of a gun or a shooter.

For me, accuracy is something that describes the ability a gun can do, all factors considered equal. Accuracy can also be used to describe the ability of a shooter. We all know a guy that can get any gun to group, no matter the day or the planet you're on.

Precision is the outcome of the two coming together. Some shooters can light up clays all day with any shotgun but couldn't hit a deer at 100yds using a rifle with a scope. The shooter is more precise with a shotgun but less precise with a rifle. Both can still be accurate, but not precise together.

-Robb
 
I once had the difference between accuracy and precision described by this illustration.

"As a method of keeping time a stopped clock is extremely precise 2 times a day but it has poor accuracy."

il.bill's picture of targets illustrate the concept exceptionally well.
 
When they turn in groups measured in millimeters, center-to-center, I would call that precision shooting.

Ah, but do THEY call it "precision shooting?" Like the magazine.

Their workmanship is definitely precise but do they use that to describe their groups?
In millimeters? Not hardly.
 
I just think of it as:

Precision is a high measure of repeatability.
Accuracy is unbiased precision.

The little target images posted by il.bill really illustrate it perfectly in post #7. I can have precision without accuracy but I cannot have accuracy without precision.

Ron
 
I love words - they give meaning to random chatter...

To answer the question of 'just a used target', No. Without information of range, arm and conditions, the proximity of holes is meaningless. What might be very good for a short barreled pocket pistol might be a terrible disappointment for a bench rest rifle. Conversely, what might be only middlin' at best for a formal target shooter might be quite impressive for a very fast series of shots fired in reaction.


How about, just for a start, entries from Merriam-Webster?

Accuracy (noun)
1. freedom from mistake or error [correctness]
2.
a) conformity to truth or to a standard or model [exactness]
b) degree of conformity of a measure to a standard or a true value — compare precision

Precision (noun)
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 — compare accuracy 2b
b) the accuracy (as in binary or decimal places) with which a number can be represented usually expressed in terms of the number of computer words available for representation <double precision arithmetic permits the representation of an expression by two computer words>
3. relevance.

Presumably the 'standard' in the definition for accuracy is 'all in the X-ring' or 'all touching' or 'perfect score'. However, most of us agree that a 'tight group' is more accurate or precise than a 'loose group' EVEN IF both score the same numerically.

I'll have to disagree with Mr. Watson - an odd occurrence. I have heard and used the term 'precision' on a firing range and in discussion of shooting in terms of delivering a shot with extreme precision upon certain occasions. Usually, the context is that of the shooter rather than the firearm.

In connotation, 'accuracy' in my experience usually relates to the mechanisms involved, the arm and ammunition; while 'precision' usually relates to the shooter. However, I freely admit, this is only my experience (and memory at this late hour) and need not be recognized by others. (Although that would imply disagreement with my sage observations - tsk, tsk.)
 
mikemyers,

my response is a bit long, so i'm going to attach the file.

the short version: i use "precision" when referring to a single shot. i use "accuracy" when referring to a group of shots.

murf

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Question?

Since we can have both accuracy and precision apply or pertain to rifle as well as handgun shooting why is this thread in handguns?

Ron
 
it can also pertain to shotguns and reloading. here probably because all his other related questions are here, also.

murf
 
the short version: i use "precision" when referring to a single shot. i use "accuracy" when referring to a group of shots.
For me personally, I think that's backwards. A single shot can only indicate the difference between the point of aim and the point of impact, the error, which is the accuracy of the (one single) shot.

With a group of shots, each shot has its own individual accuracy measurement. In a group of shots you can calculate the collection of individual accuracies. If you average the distance from the center of the shot to the center of a bulls-eye (if aiming at the center) then you can report an average accuracy.

But even average accuracy does not tell anything of the precision. The standard deviation might be an indicator of that.

Since we can have both accuracy and precision apply or pertain to rifle as well as handgun shooting why is this thread in handguns?
Good question Ron. But look at gazpacho's excellent reply above, in particular where he states:

In this exercise, we are not examining the contributing parts of the event: shooter, ammunition, firearm and environment. You can only say that all four parts contributed to the end result.
So, when considering all the variables at play in this whole game of accuracy and precision (lumped parameters for you engineers), I guess the thread could be appropriate in many areas on this board. It might be a more popular discussion in precision rifle shooting than in handgun shooting however.

Lou
 
I look at it this way: what can you say about someone who claims pi is 4.14159265358979323846264338327950288419716939937510?

Well, they are precise, because they specified pi to way too many digits. But they aren't very accurate because - at the very least - pi doesn't begin with a 4.

The ability of a gun/ammo/shooter combination to repeatedly punch holes in the same spot over and over is a function of precision.

The ability of a gun/ammo/shooter combination to punch holes in the RIGHT spot is a function of accuracy.

It is easy to think that once a gun is zeroed in those are the same, but that isn't true in my opinion. I have seen too many people take a gun I know is zeroed correctly and put a nice group off in a corner they didn't intend (precise but not accurate), or take a gun I know can punch a single ragged hole and shoot a nice evenly distributed well centered 10” circle of holes (accurate but not precise).

Most of the time precision leads to accuracy. That's why it often becomes a false goal. People who want greater accuracy chase higher and higher precision to the point that they forget about accuracy and let precision take over as the goal.

IMO
 
45_auto,

that wiki reference came up in another related thread. i dismissed it because it refers to measuring systems in an industrial setting, not a gauge of shooting performance.

since the two words are synonymous, one could use them interchangeably and still be understood.

murf
 
Accuracy is putting a bullet right where you're aiming.
Precision is putting a bullet right where you're aiming.
Feel free to differentiate if you want.
 
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