# DPMO to a Sigma Level

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- This topic has 5 replies, 3 voices, and was last updated 2 years ago by Mike Carnell.

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- October 7, 2017 at 9:29 pm #55842
Hi everyone,

I was wondering if someone could help me understand the question below, the old fashioned way (Paper, Pencil & Calculator).

The DPMO for a process is 860. What is the approximate six sigma level of the process?

6 σ = 0.8406 + √29.37 – 2.221 x ln(860)

=0.8406 + √29.37 -15.01

=0.8406 + 3.7895 = 4.63The result is 4.63

Question: Where 15.01 come from? What calculation ?

I know the 3.785 come from 29.37 -15.01 = 14.36 = √ 3.7895, but where 15.01 come from? Which calculation?

Thanks in advance I will very much appreciate the help.

Alf0October 9, 2017 at 8:52 am #201883

Chris SeiderParticipant@cseider**Include @cseider in your post and this person will**

be notified via email.Have you considered @normsdist and @normsinv with excel. There are normal distribution charts that exist to do it with paper/pencil also.

You are using the normal distribution for converting ppm defective or DPMO to sigma level. There are previous posts on this also.

Hope this helps.

0October 16, 2017 at 12:18 pm #201897

Mihail SadeanuGuest@sadeanum**Include @sadeanum in your post and this person will**

be notified via email.The correct calculation formula is:

Process Sigma = 0.8406 + SQRT(29.37 – 2.221 * (ln(DPMO))) =

0.8406 + SQRT (29.37 – 2.221 * 6.76) = 0,8406 + SQRT (29.37 – 14.9396) = 0.8406 + SQRT (14.4304) = 0.8406 + 3.7987 = 4.6393There is not any 15.01 value.

0October 23, 2017 at 2:00 am #201904

Andrew ParrParticipant@Andy-Parr**Include @Andy-Parr in your post and this person will**

be notified via email.I’m impressed that people are still wanting to understand the calculation and how to get the correct answer with pencil and paper rather than just put the numbers into the Six Sigma Calculator on here.

0June 27, 2018 at 12:02 pm #202739The 15.01 is coming from 0.8406 + SQRT (29.37 – 2.221 * 6.76), where 2.221 * 6.76 = 15.01

0July 1, 2018 at 10:32 am #202769

Mike CarnellParticipant@Mike-Carnell**Include @Mike-Carnell in your post and this person will**

be notified via email.@alf M I have attached a chart I got from Gary Cone at GPS consultants

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