Accuracy and Precision - yet again

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[email protected] said:
10 shots slow fire 25 yd one hand un-supported. Which is this??.......
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It is a target that you should frame, and hang up on your wall in a prominent location.

I think it is more likely that I will win the lottery, than that I will ever come anywhere remotely close to anything like that...... It's "what dreams are made of". :D



.....and technically, in the real world, I would say it is perfect accuracy, and perfect precision!
 
mikemyers said:
I think it is more likely that I will win the lottery, than that I will ever come anywhere remotely close to anything like that
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Keep telling yourself this and it'll surely be your reality. :( It's not coming from a place of humility, but of self-defeatism. True humility helps your shooting, but embracing self-defeating imagery will kill it.

Much better would be "Great shooting, kwhi!" ;)
 
kwhis target is the destination of shooting performance. we are trying to find the map showing us how to get there. thanks for showing us where to go, kwhi.

shooting performance = precision + accuracy

precision = group size

accuracy = sight alignment

murf
 
mikemyers,

maybe you could consider yourself as "the little engine that could" (i think i can, i think i can, etc.). one way to get over the hump.

murf
 
Ha! I've been watching the television series "The Roosevelts" for six days now, and you're right about being able to do things if you believe you can do them!!!!

Great shooting, Kwhi43!!!

The_Little_Engine_That_Could.jpg
 
I just slogged through the discussion. I will admit that I likely missed some things as I scanned for key points. I thought this was a helpful observation:

Jim Watson said:
I prefer to look at it like Jeff Cooper said:
"Since the dispersion of the weapon is added to the dispersion of the shooter, it can only be desired that the weapon have no dispersion at all."
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This makes it clear that there are at least two dimensions or constructs to assess:

One is the repeatable measure of dispersion a gun and ammunition combination is capable of (smaller is better). This would be represented by group size from a gun where the shooter is taken out of the equation, for instance by shooting the gun from a Ransom rest. By definition, whatever you call it, it is a measure of the quality of the gun/ammo combination.

The second is the ability of a shooter to apply the inherent quality of that gun/ammo to consistently put shots exactly where he or she wants them to be.

Kwhi's target demonstrates both a gun/ammo combination with repeatable low dispersion and his ability to put that low dispersion to good use by centering his shots on the target.

Those are the two constructs I think about. One is a measure of the quality of the gun (and ammo) and the other is a measure of the quality of the shooter. If that makes sense, I am open to using whatever label appropriate to each construct.
 
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mikemyers said:
I've been watching the television series "The Roosevelts" for six days now, and you're right about being able to do things if you believe you can do them!!!!
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Good series. I've been enjoying it. 3 remarkable people.


<thread veer>

We've discussed "the fundamentals" a lot, and the need to apply them well. But, truth be told, self-image trumps it all. People who are open to possibilities somehow find a way to get it done. If not, they subconsciously find a way to undermine their own efforts, often to their own frustration and disappointment.

Lanny Bassham wrote "self-mage = performance". It's very simple, but very true. He likens one's self-image to a ship's compass - the engine and crew can work hard and do the right things, but if the compass is off, all is for naught.

I may have said it bluntly, but it's an incredibly important point: A shooter must dump negative narratives about themselves if they're going to shoot to their potential. One doesn't know what their potential is; it's in the future and therefore unknown. The only way it's known is if one closes off their own path. Better shooters may be further along the path, but it certainly doesn't mean the path is closed to anyone else.

</thread veer>
 
You said, literally, "...the only remaining error is a measurement of error."
How is a measurement of error error?
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I’ve said it three different ways and none of them are particularly confusing. But I’ll start again. Here’s your initial statement:
"If you adjust the sights so that POA or a known position relative to POA is the center of the circle within which bullets fall, and you want the bullet to go where you aim the gun, then statistically the difference between where you wanted the bullet to go and where it actually goes will be (ignoring human error) the same as the precision of the shooting system."
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You use this to support your definition of precision. The problem is that the statement is just a complicated way of saying that if you assume there are only two contributing errors (one that is called accuracy and one that is called precision) that if you eliminate one of them then you are left with the other one.

In other words, your comment is just saying that once "accuracy" is eliminated as an error then the only remaining error is precision. That's obviously true no matter how one defines accuracy or precision as long as one agrees they're not the same thing and that they are the two errors that determine where a bullet hits on the target. The statement doesn’t support any definition of precision, it’s just a fancy way of restating the initial assumptions so that it’s not that obvious that it’s just a restatement of the initial assumptions.
In that case it is obvious to you why someone (not me) said that if you aren't going to make a distinction between accuracy and precision you should standardize on the word accuracy.
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There are many things which are obvious to me, and while that may be of them (or not), it doesn’t have anything to do with my point.
There actually is. You it see here on THR all the time whenever someone posts a "help me reduce my group size" post. The first steps are always a series of exercises to determine whether the issue is accuracy or precision.
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Actually there’s not and your post is clear evidence of that fact. Regardless of what the people responding believe about the definitions of accuracy and precision they still know what the person needs to do to make headway towards a resolution. Everyone knows how to advise the person along the pathway to the solution of his problem in spite of the differences of opinion expressed on this thread.

And that gets us back to my point.

What we have here is two concepts that obviously only need to be carefully defined for the purpose of discussions like this--not in any normal context. In your hypothetical thread, the solution is the same regardless of what the solver thinks about the specific definitions of accuracy and precision.

Outside of the context of this discussion, the people on both sides of this issue will go back to talking about accuracy in terms of group size. Everyone will understand what is meant, nobody will be confused, nobody will be misled, and nobody will correct the "error".

Or, more concisely--
mavracer said:
The key is knowing how to fix the problem not arguing over what to call the problem.
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JohnKSa said:
You use this to support your definition of precision. The problem is that the statement is just a complicated way of saying that if you assume there are only two contributing errors (one that is called accuracy and one that is called precision) that if you eliminate one of them then you are left with the other one.
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Sorry, no, you are fundamentally wrong. Your paraphrase is not even remotely close to what I said. You also appear to be mind locked in such a way that you can't identify your mistake.

Precision is not an error. Nor is accuracy. There is a level of abstraction you are apparently insensitive to.

Do you hunt? Ever hear the terms "game animal" and "non-game animal"? A deer is an example of a typical game animal, and a Norway rat is a non-game animal. Well, accuracy is like "game animal"...it is an abstraction for a large and variable list of concretes. Same with precision. It is an abstraction which covers a whole list of specific sources. Of course in the case of game vs. non-game you can't overlap them exactly the same way as I did in my accuracy overlapping precision example, but that's because what game, accuracy, non-game, and precision share is that they are all abstract, not that they can be expressed geometrically.

Accuracy and precision are measures of different types of error. They are not themselves error, and they are not the same.
 
Ed Ames said:
......you are fundamentally wrong........
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From my little corner of the world, neither of you is "wrong". You're both just explaining how you see the world. "Different" would be a better term than "wrong".



I no longer think there is one single correct explanation for the terms "accuracy" and "precision", but I think anyone who's read this thread is more likely to use both terms more correctly. I know I am. ......and even so, I just wrote "more correctly" rather than "correctly". I did that on purpose.

(P.S. - One year ago, I'd have used the terms interchangeably, as if they meant the same thing. Not any more.)
 
Precision is not an error. Nor is accuracy.
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Accuracy and precision are measures of different types of error.
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Interesting. In post #55 of this thread I restated one of my previous comments that you had objected to, in two additional ways to try to find the specific wording/shade of meaning that worked for you.

In that post one of my restatements referred to accuracy and precision as measures of error. Apparently you chose to ignore that reference and respond to the one that you didn't like instead. That's sort of an unusual response since most people readily understand that when a person states something in multiple ways, all the restatements mean the same thing and are provided for the purpose of clarification. If one of the restatements clarifies things for the listener, then that should put an end to the confusion about the meaning and allow communication to take place. Ignoring the restatement you agree with so that you can voice disagreement with the ones that don't provide you with clarification is antithetical to the goal of establishing communication.

Well, all that aside, 4 days later you're good with calling accuracy and precision measures of error. So, on that note, let's try it one more time using your preferred wording to bypass the quibbling and actually communicate.

The problem is that the statement is just a complicated way of saying that if you assume there are only two measures of error (one that is called accuracy and one that is called precision) that if you eliminate one of them then you are left with the other one.

That's obviously true no matter how one defines accuracy or precision as long as one agrees they're not the same thing and that they are the two measures of error that determine where a bullet will hit on the target vs. where it was intended to hit. The statement doesn’t support your definition of precision, it’s just a fancy way of restating the initial assumptions so that it’s not that obvious that it’s just a restatement of the initial assumptions.

I think that this highlights what I've been trying to say all along. The context of this particular discussion is one where pedantism rules at the expense of "reasonable assumptions" and practical, real-world approaches to problem-solving.
 
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Not really going to read/respond to most of this because we seem to have cemented our respective positions.

JohnKSa said:
The context of this particular discussion is one where pedantism rules at the expense of "reasonable assumptions" and practical, real-world approaches to problem-solving.
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Shrug. I don't really think of basic tenets of engineering as pedantry, bit maybe that is pedantic of me. On the other hand, I'm not being that pedantic: I countenanced just using "accuracy" for everything, and only tried to explain the nuance of meaning when someone kept insisting that accuracy and precision are interchangeable.

But...yes, you can use them interchangeably. You can also say it is a "mute" instead of "moot" or "peak" instead of "pique". :) If the president of the USA can call "corpsmen" "corpse men" I don't see why you can't interchange accuracy and precision.

It's all good. :)
 
I was looking around to see how others used these words, and came upon a small but interesting web page, that considers all this from a mathematical viewpoint:

They even bring up a third term:
"Bias is a systematic (built-in) error which makes all measurements wrong by a certain amount."​

I've never noticed anyone using "bias" in connection with shooting, but it would be a very good explanation to use for things such as mis-aligned sights, or a stiff breeze to one side. I think it would be useful to include "bias" in the definitions we were trying to come up with.

Other than that, the page more or less reinforces the "common sense" definitions we've been coming up with.
 
Bias is a departure from the desired that does not vary over the measurement timeframe. If it varies (isn't constant) over the measurement timeframe then it would not be accurate to characterize it as a bias.

If your sights are misaligned significantly, you will likely see a bias on the target--the center of the group will not be at the point of aim due to the bias created by the sight misalignment. That point of aim bias won't change unless the relationship of the sights and barrel are altered.

Switching from one kind of ammunition to another could induce a point of impact bias. The differences in the two kinds of ammo might result in a point of impact bias between targets shot using the same aiming point but with each kind of ammunition.

The term may not be commonly used, but as in the examples, some types of shooting errors are clearly biases. Others aren't.

Here's a pretty good start at listing the common errors related to shooting without trying to give each one a formal name.
  • Where the shooter aims the sights vs. where the shooter wants to aim the sights. (Sight alignment error, lack of visual acuity, carelessness, etc.)
  • Where the sights end up being aimed at the instant of discharge vs. where the shooter actually aimed them. (Flinch or other involuntary movement.)
  • Where the gun itself is aimed vs. where the sights are aimed. (Improperly zeroed sights, sights misaligned due to damage or defects, barrel misaligned due to damage or defects.)
  • Inconsistencies in the bullet impact due to effects imposed by the firearm itself. (Barrel vibration, inconsistent stock pressure, loose screws, crown defects, inconsistent primer strikes, etc.)
  • Inconsistencies in the trajectory due to effects imposed by the ammunition. (Powder charge differences, variations in case volume or bullet seating depth, defects in the bullet, case or primer, etc.)
  • Inconsistencies in the trajectory due to external effects on the gun. (The sun heats one side of the barrel more than the other bending the barrel slightly. Ambient temperature slightly alters the firearm's dimensions. Fouling or corrosion builds up in the barrel or chamber.)
  • Inconsistencies in the trajectory due to external effects on the ammunition. (Ambient temperature differences alter the discharge pressure. Ammunition becomes contaminated or is degraded by external factors such as age.)
  • Where the bullet hits vs. where the bullet would hit if there were no external effects acting on the bullet in flight. (Wind, magnus effect, spin drift, air pressure differences, leaves, branches, etc.)
  • Where the bullet hits vs. where the bullet would hit if there were no frame of reference issues. (Coriolis effect, shooting at a significant upwards or downwards angle, moving platforms or targets, etc.)
 
mikemyers said:
I was looking around to see how others used these words, and came upon a small but interesting web page, that considers all this from a mathematical viewpoint:

They even bring up a third term:
"Bias is a systematic (built-in) error which makes all measurements wrong by a certain amount."​

I've never noticed anyone using "bias" in connection with shooting, but it would be a very good explanation to use for things such as mis-aligned sights, or a stiff breeze to one side. I think it would be useful to include "bias" in the definitions we were trying to come up with.

Other than that, the page more or less reinforces the "common sense" definitions we've been coming up with.
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Bias has been used throughout the thread. My initial definition of accuracy (post #15) was unbiased precision and in post #85 I defined bias as a deviation from mean. So in shooting I figure bias is deviation from the target center or point of aim. Bias is used as a quantitative term so we can assign a numeric value to the deviation.

Ron
 
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,
Attached Thumbnails
Click image for larger version
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Precisely, I mean that's accurate.
 
Bobo said:
Accuracy vs Consistency
is a better way to determine shooting than
Accuracy vs Precision....
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Maybe it's just me, but as I see it, consistency has to do with what "the shooter" does, as in holding the gun the same way each time, pulling the trigger the same way, lining up the sights, and so on.

Precision has everything to do with where the shots hit on the target.

To me, if it has to do with your muscles, your eyes, and so on, that's trying to be consistent. If it has to do with where the bullets actually hit the target, that's precision. .....at least the way I think about this stuff. I don't think the two words are interchangeable.
 
Consistency
Conformity in the application of something, typically that which is necessary for the sake of logic, accuracy, or fairness.
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While I can see the analogy between precision and consistency when we look at shooting I tend to agree with mikemyers. I also can see where a tight group would be considered a consistent group. Obviously the author of the linked article, Defensive (Combat) Accuracy, felt consistency to be a better choice of words. Interesting article by the way.

If the shooter consistently applies good shooting habits (as in holding the gun the same way each time, pulling the trigger the same way, lining up the sights, and so on) the end result will be unbiased precision resulting in accuracy.

Then too, how we look at the terms accuracy and precision really depends on background I guess. A mechanical or electrical engineering type likely will not see the terms defined the same as a chemist for example.

Ron
 
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