# Significance of 5.15 in Gage RR Study

Six Sigma – iSixSigma Forums Old Forums General Significance of 5.15 in Gage RR Study

Viewing 7 posts - 1 through 7 (of 7 total)
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• #35104

chugh
Member

Hello Everybody ,
Well I was Just trying to see why the (No Of Standard Deviations)
Study Variation was 5.15 as default in Minitab (Options in Gage R&R STUDY CROSSED)in Earlier Versions.
If it is really the No is standard deviations , they Y not 6 from the begining.
Can anyone say any thing on this .

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#97701

Mikel
Member

It’s a historical artifact from when this stuff started in 1962. It represents 99% of the variation instead of 99.73%

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#97772

chugh
Member

Dear Stan, thanks for your reply .
But tell me if this was just a Historical Routine to take 5.15 as the conversion factor , Y did they not take 6 , which is more accurate.

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#97777

B.S.Ravi
Participant

5.15 is for confidence limit of 99%.6 is used for 99.73% cofidence limit.

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#97792

Mikel
Member

Why not 7 or 8 or 9 which would be even more accurate?
What is important is to have a standard method of calculating and a standard method of judging the result.
The rules for judging the result are tied to the factor you use for multiplication (5.15 or 6). The truth is that the rules for < 10% for % Study is great and < 30% is generally accepted is very conservative.
Go play with the formulas and the rules and see how little difference they make at these conservative levels for acceptance. If you don’t know how, repost and I’ll post an example later today.

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#97801

Mikel
Member

By the way – my bad. The 5.15 or 6 only affects % Tolerance. I still encourage you to quantify the impact of the 5.15 vs. 6 with relation to the rules.

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#103529

gutierrez
Participant

Some people told me that for unilateral tollerance used 2.33 and for bilaterla tolerance used 5.15.
Can I doing thatt in R&R????

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Viewing 7 posts - 1 through 7 (of 7 total)

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