How to correctly calculate sigma level for production processes

P

Przemek

Dear All,
I try to calculate and evaluate sigma level for production processes in my company.
How to do this correct what kind of datas I should collect. Maybe somebody have any experiences
Thanks a lot for support.
Przemek
 

Jen Kirley

Quality and Auditing Expert
Leader
Admin
Hello,

Please see the related threads at thebottom of this page. I think you will find at least one good answer to yoru question - I took a peek at one of them and it appeared to hit the bullseye. Please let us know if that is not the case after all.
 

Miner

Forum Moderator
Leader
Admin
What type of data do you have available?

If variable data that are normal distributed:

  • Sigma ST = ZST = Cpk * 3 (Cpk = 2 is a Z-score of 6 is a Short Term Sigma level of 6
  • Sigma LT = ZLT = Ppk * 3 (Ppk = 2 is a Z-score of 6 is a Long Term Sigma level of 6

If attribute data are available, calculate the percent defective. Using a Z - table look up the Z-score corresponding to a p-value equal to the percent defective. The Z-score is your sigma value.
 
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