Oil Analysis Accuracy

Another good one (with added info) showing what accuracy and precision are defined to be.

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What happens if one is taking vitamin or Iron supplement and contaminates the sample? 🤣
You laugh. The days I ran the ICPMS I couldn't wear deodorant as even with a lab coat the aluminum in the deodorant would cause measurable contamination. Our ammonia technique was so sensitive that you set up the run and left the lab because the ammonia in your breath would contaminate the samples.

Of course we're not talking about UOA level detection limits here. We were working in low single digit parts per billion, parts per trillion, and even into the parts per quadrillion with the ICPMS.

Ed
 
You laugh. The days I ran the ICPMS I couldn't wear deodorant as even with a lab coat the aluminum in the deodorant would cause measurable contamination. Our ammonia technique was so sensitive that you set up the run and left the lab because the ammonia in your breath would contaminate the samples.

Of course we're not talking about UOA level detection limits here. We were working in low single digit parts per billion, parts per trillion, and even into the parts per quadrillion with the ICPMS.

Ed
That's like the enviro samples, ppb. We would have blanks ("trip blanks") that were a vial of deionized water that got delivered with the sample containers, went to the field, then back to the lab and analyzed to look at things like this. The mineral; exploratoin work is very different but we still send in inert blanks (often just pure quartz) to be run to have a look at well the lab cleans their equipment.
 
Another good one (with added info) showing what accuracy and precision are defined to be.

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Z,

I have a hard time with the "high accuracy" of the lower right image.
Closeness of the 5 shots to the bullseye in this image, is worse than the upper right image, which was given as a "low accuracy" example!

Re: Lower Right Image
Could it be that they meant to have the shots (red marks) on the most inner yellow circle as opposed to the outer yellow circle? Meaning the exact same relative shot locations but on the most inner yellow circle instead? And that would provide a relatively accurate but not precise (high accuracy, low precision) example!
 
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Z,

I have a hard time with the "high accuracy" of the lower right image.
Closeness of the 5 shots to the bullseye in this image, is worse than the upper right image, which was given as a "low accuracy" example!

Re: Lower Right Image
Could it be that they meant to have the shots (red marks) on the most inner yellow circle as opposed to the outer yellow circle? Meaning the exact same relative shot locations but on the most inner yellow circle instead?
I think they said it's "high accuracy" because all the shots are exactly the same distance away from the bullseye. The precision is obviously really bad because all the shots are not grouped closely together like in the lower LH example (high precision & high accuracy). The example in post 40 is more clear.

Here's another example.

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I think they said it's "high accuracy" because all the shots are exactly the same distance away from the bullseye. The precision is obviously really bad because all the shots are not grouped closely together like in the lower LH example (high precision & high accuracy). The example in post 40 is more clear.

Please see my edit.

I have a feeling they wanted the shots on the most inner yellow circle!

I agree, post #40 is more clear!
 
First off to be clear, I don't know or care how this applies to oil analysis....... With that said, when someone makes the statement that a rifle is "accurate", it means it is capable of placing shot after shot in the tightest group possible.

Benchrest competition is a good example of this. Benchrest rifles are considered to be some of the most accurate rifles in existence. The man / rifle combination that shoots the tightest group wins. Where it prints on the target is meaningless as to scoring.

If you look at a benchrest target it has a small square above the bullseye. That is what the scope is dialed in to, (or somewhere close), so the group deliberately prints low. This is done purposely in order to not shoot out their aiming point.

The above middle 2 targets shown are wrong as to the term, "accurate". Any scope can be adjusted to print whatever group the rifle is capable of shooting, (tight or loose), anywhere within its full range of adjustment. It has nothing to do with the overall accuracy of the weapon it is mounted to.

ACCURATE :

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INACCURATE :
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First off to be clear, I don't know or care how this applies to oil analysis.......
These were shown because the discussion was about the accuracy and precision of UOA test data. Could be applied to anything that is measured.

With that said, when someone makes the statement that a rifle is "accurate", it means it is capable of placing shot after shot in the tightest group possible.
Yeah, that's shown in the accuracy & precision examples, which are pretty self explanatory - and are correct. As shown in the examples, a rifle (or anything else) could be very high precision, but not be accurate.

ACCURATE :

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That's technically both accurate and precise, just as the examples show.

INACCURATE :
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I'd say that's inaccurate and also not precise at the same time.
 
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Benchrest competition is a good example of this. Benchrest rifles are considered to be some of the most accurate rifles in existence. The man / rifle combination that shoots the tightest group wins.
The guy that wins is the one that has both accuracy and precision. One could shoot a very tight group (ie, precision), but that group could be far way from the bullseye ... ie, inaccurate. Accuracy and precision are two separate unrelated things. Having both is the goal.

This guy won ... had both accuracy and precision.

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This guy didn't win ... he should have sighted the sites in better to make it accurate, but it shot very precisely.

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The guy that wins is the one that has both accuracy and precision. One could shoot a very tight group (ie, precision), but that group could be far way from the bullseye ... ie, inaccurate. Accuracy and precision are two separate unrelated things. Having both is the goal.

This guy won ... had both accuracy and precision.

View attachment 232565

This guy didn't win ... he should have sighted the sites in better to make it accurate, but it shot very precisely.

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Not really. Because in Benchrest competition, it doesn't matter where the grouping prints on the target. Or where the gun is "sighted in", as you put it.

The tightest group wins... Period. This regardless of where the group is shot on the paper. All that matters is who shot the tightest group. And that will always be the guy with the most accurate rifle / load combination.

This is because it really doesn't take any skill to dial in a scope where to print off a rest. The talent that is required to win these matches is derived by the skill of the handloader, and the accuracy of the rifle.

To be perfectly honest, this whole exercise amounts to picking fly crap out of the pepper. Because the sport of benchrest shooting is often referred to as, "Precision Benchrest Shooting".... But it takes a very accurate rifle to compete and win.
 
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I'd say that's inaccurate and also not precise at the same time.
I have to admit it's not a very good example, because it's a target I shot at 25 yards with a Sig P-226 with cheap, bulk factory hardball ammo.

And I'm comparing it to a heavy barrel target rifle, that was shot off a rest with handloaded ammunition. So it's apples to oranges. I just used it for a visual comparison to illustrate the difference.
 
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Not really. Because in Benchrest competition, it doesn't matter where the grouping prints on the target. Or where the gun is "sighted in", as you put it.

The tightest group wins... Period. This regardless of where the group is shot on the paper. All that matters is who shot the tightest group. And that will always be the guy with the most accurate rifle / load combination.
I'm giving examples of precision and accuracy. What you are describing here is only precision. Technically speaking in this instance, it's the guy with the most precise rifle that wins. If that tight group was hitting exactly were the intended goal was to make that tight group hit (like the bullseye being the goal), then the rifle would be both precise and accurate. There is a distinct difference between precise and accurate, and they are two separate unrelated things.

This is because it really doesn't take any skill to dial in a scope where to print off a rest. The talent that is required to win these matches is derived by the skill of the handloader, and the accuracy of the rifle.
No, again ... it's the precision of the rifle you're talking about. Yes, there is some "shooter" (operator) skill factor too, but if you put the rifle in a good gun vice and shot it 10 times and it had a very tight group then it would be a "precise" shooting rifle. If it didn't have a tight group, it would not be considered very precise. This is the shooting MOA of the gun itself, without any human factor involved. The MOA of the rifle is defining how precise it shoots.

The accuracy would only be related to where that shot group ends up on the target ... typically on the bullseye is the goal. That's why guns have sights on them, so you can adjust them (calibrate them) to make the gun shoot accurately. A gun with a horrible MOA (ie, not a precise shooting gun), even if it shoot accurately, will be putting a loose group around the bullseye if the gun is sighted in to "accurately" hit the bullseye.

To be perfectly honest, this whole exercise amounts to picking fly crap out of the pepper. Because the sport of benchrest shooting is often referred to as, "Precision Benchrest Shooting"....
Not really ... it's a discussion to properly understand the distinct difference between precision and accuracy. If bench shooting is refereed to as "Precision Benchrest Shooting" then they are correct with that terminology if all they are looking at is the grouping and not concerned at where that group hits the target. They are looking only at the precision (both gun and operator) and not caring about where the gun's sighting system is adjusted to place the group on the target.

But it takes a very accurate rifle to compete and win.
No ... it actually takes a precise shooting rifle to compete and win if all they are judging is the grouping, regardless of where the shot group is on the target ... like this previous example.

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When you ask a fellow rifle shooter: "Hey, what's the precision of your rifle?" ... he should technically respond with something like: "It's MOA is 1/2 inch" ... meaning it should be precise enough to make a 1/2 inch group at 100 meters.

If someone says: "My rifle has 1/2 inch MOA", he's technically describing the shooting precision of the rifle ... not the "accuracy". A precise shooting rifle can also be made to shoot accurately by adjusting (calibrating) the sights to make it shoot exactly where you want it to. Then it's both precise and accurate.

Below is why people don't understand the difference between precision and accuracy, because stuff like this is all over the internet. It should technically say: "When the accuracy PRECISION of a gun is given in minutes of angle, it is possible for a person to know approximately what size groups the gun shoots within its effective range."

The MOA grouping of a rifle (without any human factors) is defining the gun's shooting precision.

When misinformation is constantly shown all over the internet it makes people form misconceptions and start using the wrong terminology or start making up their own definitions of terms.

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"Weatherby Guarantees SUB-MOA Accuracy within Two-Years of Verified Purchase Date to Original Purchaser".

"Together, the Weatherby system (premium ammunition and rifle) forms the flattest shooting, hardest hitting, most accurate combination in the industry today.


Sorry ... they are also technically using the wrong terminology. They may purposely use the wrong term because that's what people are use to seeing, and don't really understand the difference between precision and accuracy. A rifle's MOA performance is only describing how precisely it shoots. The accuracy is dependent on the sights and if they are "calibrated" (ie, "sighted in") correctly to put the bullets where the shooter wants them. Accuracy is basically adjustable, but the precision isn't ... it's part of the design and manufacturing of the rifle ... you get what you get in terms of its precision - its MOA performance.

The rifle's MOA can be determined without the rifle being accurate ... you just need to see the MOA grouping anywhere on the target to see it (your "Precision Benchrest Competition" example). Use a gun vice to take out the operator's use error, and you will see the true MOA precision of the rifle. After that, if you adjust (calibrate) the sights to put that group on the bullseye, then the rifle is both precise and accurate, as the many examples given show.

The terminology is used wrong all over the internet, and that locks in misconceptions in people's heads on the actual correct terminology. That's why lots of people really don't know the technical difference between the definition of precision and accuracy wrt the scientific measurements, and also with rifle performance in this context.

Next time you're at the rifle range, ask everyone there if they know the difference between their rifle's precision and accuracy. The are technically two totally different things as shown many times in this thread. The same goes for measuring about anything. A digital micrometer (or any other measuring tool, like machines used in UOAs) might be very precise, but it could be very inaccurate.
 
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