Talk:Process capability index

I corrected the notation for "variability of the process" to standard deviation to avoid confusion between sigma and sigma squared, variance/variability, and standard deviation. Hyoga 11/26/2007

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There is no point in listing an equation if you are not going to define what the variables mean. Namely, what on earth is do USL and LSL stand for? Even sigma should be defined for those who do not know what they are looking at.

Fixed. --mabahj 11:00, 12 July 2006 (UTC)

USP - Upper Specification Limit LSL - Lower specification Limit These are related to statistical process control (SPC). -- Manaf 28 June 2007 (EST)

... and how are these interpreted?

It would be really helpful, I think, if someone could add a sentence or two for each measure to say what a "good" value is ... e.g., 1.0 is good, higher is better, things like that. Sn14534 13:13, 19 July 2007 (UTC)

C_pk

I have noticed that the Ckp value equation has an mistake; there shoud be T instead of µ (targed instead of estimated/calculated mean). If µ is used, the result is PPk. Could someone make the correction, please.

Antti 29th Aug 2007 —Preceding unsigned comment added by 192.130.237.254 (talk) 06:57, August 29, 2007 (UTC)

• C_pk does not take the target, T, into account according to NIST (http://www.itl.nist.gov/div898/handbook/pmc/section1/pmc16.htm) or Montgomery (http://he-cda.wiley.com/WileyCDA/HigherEdTitle/productCd-0471656313.html). Perhaps you're thinking of a variant on C_pk that does? — DanielPenfield 16:24, 5 September 2007 (UTC)

Is there a missing word in the following clause? 'is', maybe? And is this English? I'd much prefer "Because the process capability..."

Being the process capability a function of the specification

--71.10.226.43 (talk) 12:28, 18 September 2009 (UTC)