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dbulak
Does anyone know the origin of the 10:1 ratio for gauge equipment? I have found books that talk about it but none refer to where it originated.
Re: The Origin of the 10:1 Resolution Ratio for Gauge Equipment
Common sense? It can be 4:1 too, but the principle is the same. If you want to have accuracy, the master must be capable of resolving to 1/10th of the measurand.
Common sense? It can be 4:1 too, but the principle is the same. If you want to have accuracy, the master must be capable of resolving to 1/10th of the measurand.
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dbulak
Re: The Origin of the 10:1 Resolution Ratio for Gauge Equipment
What does this response have to do with determining the origin of the 10:1 rule? I seem to be lost. I thought my question was straightforward.
What does this response have to do with determining the origin of the 10:1 rule? I seem to be lost. I thought my question was straightforward.
Re: The Origin of the 10:1 Resolution Ratio for Gauge Equipment
I guess Andy is saying he doesn't know.
Re: The Origin of the 10:1 Resolution Ratio for Gauge Equipment
Hello there!
Yes it was clear. Andy's an awesome guy, and didn't mean anything by the response. He was merely suggesting that he's not sure if there is a classical derivation of the ratio, as it appears to be the product of a mathematical/ probabilistic calculation.
May I direct a question back and ask what the nature is of your question? Are you just wondering why the 10:1 as opposed to 7:1? Are you trying to understand what the ratio means?
Hello there!
Yes it was clear. Andy's an awesome guy, and didn't mean anything by the response. He was merely suggesting that he's not sure if there is a classical derivation of the ratio, as it appears to be the product of a mathematical/ probabilistic calculation.
May I direct a question back and ask what the nature is of your question? Are you just wondering why the 10:1 as opposed to 7:1? Are you trying to understand what the ratio means?
Re: The Origin of the 10:1 Resolution Ratio for Gauge Equipment
Thanks, Brad. I could have used 'consensus' which would have served better.
I've never found the 'root' of reasons for selecting this ratio, even if it is specified in books etc. As I'm sure the OP knows, the idea is to make a measurement which is close to the measurand 'true' value, perhaps as part of understanding the overall deviation from the this value.
E.g. if the measurand true value is an inch, then (clearly) if the measuring equipment is capable of reading to 0.1", the error will be within +/- 0.1". The factor of cost-benfit comes into play here, since the greater the accuracy, the higher the cost, in general terms.
Yes, Al is correct. I don't know - but at least I'm in good company........
Thanks, Brad. I could have used 'consensus' which would have served better.
I've never found the 'root' of reasons for selecting this ratio, even if it is specified in books etc. As I'm sure the OP knows, the idea is to make a measurement which is close to the measurand 'true' value, perhaps as part of understanding the overall deviation from the this value.
E.g. if the measurand true value is an inch, then (clearly) if the measuring equipment is capable of reading to 0.1", the error will be within +/- 0.1". The factor of cost-benfit comes into play here, since the greater the accuracy, the higher the cost, in general terms.
Yes, Al is correct. I don't know - but at least I'm in good company........
Re: The Origin of the 10:1 Resolution Ratio for Gauge Equipment
I made a quick look through the library. Somewhere there is a chart that shows the %confidence level you have the larger the ratio. Thus, as the ratio gets smaller, the confidence level gets smaller-akin to the "blind leading the blind".
I did find a book that was pretty heavy on the math side. But, it had a good list of references, if that will help.
Measurement Errors and Uncertainties, Theory and Practice, 2nd. Ed.; Semyon G. Rabinovich (Springer-Verlag New York)
Edit-Added
In the above book, I found several references from the early 70's. There was one citation from 1931, but it was German, so I am not sure what it was about
I made a quick look through the library. Somewhere there is a chart that shows the %confidence level you have the larger the ratio. Thus, as the ratio gets smaller, the confidence level gets smaller-akin to the "blind leading the blind".
I did find a book that was pretty heavy on the math side. But, it had a good list of references, if that will help.
Measurement Errors and Uncertainties, Theory and Practice, 2nd. Ed.; Semyon G. Rabinovich (Springer-Verlag New York)
Edit-Added
In the above book, I found several references from the early 70's. There was one citation from 1931, but it was German, so I am not sure what it was about
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D.Scott
Re: The Origin of the 10:1 Resolution Ratio for Gauge Equipment
That is a pretty tough question but maybe we can "piece" together an answer for you.
As for the use of the 10:1 ratio in relation to gages - as you already indicated, you understand the ratio is used in a gage R&R to help define the variation in the measurement system. Obviously if you used a 1:1 scale you would have too little variation. Adding the extra decimal you highlight the slight variations.
Researching the measurement system analysis which makes use of the 10:1 ratio shows us that in 1963 C. Eisenhart defined measurement as "the assignment of numbers to material things to represent the relations among them with respect to particular properties". This led to development of Measurement System Analysis This early MSA didn't define a 10:1 ratio. It required a discrimination (or resolution) but one could use 4:1 or in some cases 2:1
Later refinement of the MSA was done by the military and later ASTM. The 10:1 ratio is now used as a "rule of thumb" by ASTM and the OEM MSA Reference Manual 3rd edition.
So, to sum it up, the earliest use of the 10:1 ratio used for gage equipment would have to go back to an early gage R&R and very possibly to Eisenhart.
Dave
That is a pretty tough question but maybe we can "piece" together an answer for you.
As for the use of the 10:1 ratio in relation to gages - as you already indicated, you understand the ratio is used in a gage R&R to help define the variation in the measurement system. Obviously if you used a 1:1 scale you would have too little variation. Adding the extra decimal you highlight the slight variations.
Researching the measurement system analysis which makes use of the 10:1 ratio shows us that in 1963 C. Eisenhart defined measurement as "the assignment of numbers to material things to represent the relations among them with respect to particular properties". This led to development of Measurement System Analysis This early MSA didn't define a 10:1 ratio. It required a discrimination (or resolution) but one could use 4:1 or in some cases 2:1
Later refinement of the MSA was done by the military and later ASTM. The 10:1 ratio is now used as a "rule of thumb" by ASTM and the OEM MSA Reference Manual 3rd edition.
So, to sum it up, the earliest use of the 10:1 ratio used for gage equipment would have to go back to an early gage R&R and very possibly to Eisenhart.
Dave
Re: The Origin of the 10:1 Resolution Ratio for Gauge Equipment
Just a side here............
The 10:1, just like the 4:1 originally comes out of the days when there was a land bridge to Russia and so forth.....in other words the old MIL-STD-45662A and before days.....
In those days 4:1 was considered minimum and 10:1 considered optimum.....
Now, 4:1 is recognized and accepted pretty much everywhere in the world.....
HOWEVER.....
The U.S. is the only one (to my knowledge) to FORMALIZE the rule.....in both ANSI/NCSL Z540-1-1994 and ANSI/NCSL Z540.3-2006.....thus making it immune (in theory) from APLAC/ILAC review.....
Hope this helps.....
Hershal
Just a side here............
The 10:1, just like the 4:1 originally comes out of the days when there was a land bridge to Russia and so forth.....in other words the old MIL-STD-45662A and before days.....
In those days 4:1 was considered minimum and 10:1 considered optimum.....
Now, 4:1 is recognized and accepted pretty much everywhere in the world.....
HOWEVER.....
The U.S. is the only one (to my knowledge) to FORMALIZE the rule.....in both ANSI/NCSL Z540-1-1994 and ANSI/NCSL Z540.3-2006.....thus making it immune (in theory) from APLAC/ILAC review.....
Hope this helps.....
Hershal
Re: The Origin of the 10:1 Resolution Ratio for Gauge Equipment
Yes! Now I realize this answer probably does not come across as the most "metrological" answer. But, realizing a 10 to 1 ratio is also expensive. Say I am calibrating a thermometer to +/-1 C. The standard that I have is +/-.25C is far less expensive than the standard that is +/-.1C. Not only does the device cost more, the cost of calibration is more expensive.
I generally try to maintain the 4 to 1 as a rule of thumb. A few standards (mass standards and Relative Humidity) are two that many time fall below the 4 to 1.
Yes! Now I realize this answer probably does not come across as the most "metrological" answer. But, realizing a 10 to 1 ratio is also expensive. Say I am calibrating a thermometer to +/-1 C. The standard that I have is +/-.25C is far less expensive than the standard that is +/-.1C. Not only does the device cost more, the cost of calibration is more expensive.
I generally try to maintain the 4 to 1 as a rule of thumb. A few standards (mass standards and Relative Humidity) are two that many time fall below the 4 to 1.
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