How is DPMO converted to Sigma
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 This topic has 9 replies, 8 voices, and was last updated 18 years, 10 months ago by SixSigmaGuy.

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November 13, 2001 at 3:22 am #28213
There is a six sigma conversion table in the book of “The Six Sigma Way : How GE, Motorola, and Other Top Companies Are Honig Their Performance by Peter S. Pande, Robert P. Neuman, Roland R. Cavanagh.
I wonder how DPMO is converted to sigma. Anyone can help me?
Thank you.0November 13, 2001 at 2:03 pm #69932
Jaran S.Participant@JaranS. Include @JaranS. in your post and this person will
be notified via email.1. Calculate DPMO for each sigma level, using 1.5 sigma shift
assumption. It is based on normal distribution assumption also.
2. You can get the relation between sigma level and DPMO.
3. When you get any DPMO, then I estimate sigma level by using the
relation you get.
4. This may not be valid but it is the way to express process capability
with attribute data into same process capability unit, sigma level.
Jaran S.0November 13, 2001 at 3:04 pm #69934
Bonnie ParisParticipant@BonnieParis Include @BonnieParis in your post and this person will
be notified via email.I recommend that you check out the
0November 16, 2001 at 3:02 am #70002Thank you Jaran S. and Bonnie Paris.
0November 19, 2001 at 1:03 pm #70028
EMillerParticipant@EMiller Include @EMiller in your post and this person will
be notified via email.Hoon –
My company produces software for just this purpose. Please browse to http://www.hertzler.com/html/prod_dms.asp for information, or send me an email at [email protected]. You might also find this page useful: http://www.hertzler.com/html/prod_6sigma.asp.
Regards,
Evan0November 19, 2001 at 8:06 pm #70042
schaeffersMember@schaeffers Include @schaeffers in your post and this person will
be notified via email.Dear Mr Hoon,
The sigma is calculated by transforming the defects to a normal distribution. There is a formula to do it. However you can just use the sigma calculator. This is freeware software which converts defects, subgroupsizes and opportunities to a sigma number. In the help screen you can also find the sigma conversion table. You can just download this freeware from http://www.spcwizard.com look for the 6 sigma page.
0November 20, 2001 at 6:19 am #70053
SixSigmaGuyParticipant@SixSigmaGuy Include @SixSigmaGuy in your post and this person will
be notified via email.I wanted to add to the other replies that you don’t always want to include the 1.5 sigma shift. It depends on the process you are working with. For example, with Transactional processes you don’t want to do the shift.
0November 20, 2001 at 7:26 pm #70075Using:
Sigma =NORMINV(1DPMO/1000000,1.5,1)
The Excel NORMINV function’s estimate of Sigma is accurate to two decimal places between 1.4 and 5.7 Sigma. It is accurate to one decimal place between 5.7 and 6.1 Sigma.
Using a much longer formula:
Sigma =SQRT(LN(1/(1EXP(DPMO/1000000))^2))(2.55155+0.802853*SQRT(LN(1/(1EXP(DPMO/1000000))^2))+0.010328*SQRT(LN(1/(1EXP(DPMO/1000000))^2))^2)/(1+1.432788*SQRT(LN(1/(1EXP(DPMO/1000000))^2))+0.189269*SQRT(LN(1/(1EXP(DPMO/1000000))^2))^2+0.001308*SQRT(LN(1/(1EXP(DPMO/1000000))^2))^3)+1.5
This “long” formula is accurate to two decimal places between 3.2 and 9 Sigma. It is accurate to one decimal place between 2.5 and 3.2 Sigma. It should not be used below 2.5 Sigma or above 9 Sigma.0November 22, 2001 at 3:26 pm #70121
Ricardo MouraMember@RicardoMoura Include @RicardoMoura in your post and this person will
be notified via email.Hi,if you have the DPM or DPMO, you can obtain the sigma level without any specification limits, using the following equation:sigma level = 0.8406 + sqrt[29.372.221*ln(DPM or DPMO)](sqrt=square root and ln=natural logarithm)this equation returns the sigma level + 1.5 sigma shift, and we can assign then to the “sigma capability”. If you don’t want the sigma shift, you can subtract 1.5Bye,Ricardo.
0November 22, 2001 at 7:31 pm #70129
SixSigmaGuyParticipant@SixSigmaGuy Include @SixSigmaGuy in your post and this person will
be notified via email.This is great. Does it mean I can throw away my tables? :)
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