I have attached a form for calculating Cp and Cpk, however it appears that my calculation for Cpk is actaully calculating Ppk. Can someone help my formula?
If the values are consectutive, you can use the moving range to caluclate short term variability (s=movRbar/1.128). For your data the difference is very small.
Subgroup size is one. Yes they were sequential, numbered as they came out of the press.
What I'm really curious about is what is wrong with my calculation? The value I am getting in my sheet is what MiniTab gives me for Ppk. MiniTab is giving me a Cpk of 1.02
s = Standard Deviation.
For Subgroup Size of 1,
movR = Moving Range = absolute difference between two consecutive readings.
movRBar = Average Moving Range: Average of all moving Ranges of all pairs of consecutive readings.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.