Talk:Process capability index: Difference between revisions

Revision as of 23:09, 5 November 2016

Revision as of 23:17, 5 November 2016

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:No, they're correct. For process capability to be valid, the process must be stable, so yields of Φ(sigma level) - Φ(-sigma level) as given in the table (in the article coupled with this talk page) are correct. As the [[Six Sigma]] article indicates, the yields presented there represent the worst case deterioration of 1.5σ before a [[control chart]] is expected to catch the shift or drift, so yields of Φ(sigma level - 1.5) - Φ(-sigma level - 1.5) (for a shift or drift upward; a shift or drift downward is equivalent—you can do the math) are correct in that article. No action required. -- [[User:DanielPenfield|DanielPenfield]] ([[User talk:DanielPenfield|talk]]) 10:02, 27 January 2014 (UTC)

Example shown has a std. deviation that seems to not match chart data. Mu hat estimate (98.9894) is correct, but estimated chart data std. deviation is ~0.869 (unbiased) or ~0.842 (std. population deviation), not 1.03, as stated.

..unless I am missing something or a different method is used for this? Any comments/clarification very welcomed and appreciated.