Quality Advisor

A free online reference for statistical process control, process capability analysis, measurement systems analysis, and control chart interpretation, and other quality metrics.

Process performance indices

Process performance indices use sigma of the individuals .

Pp

pp formula

Pp for one-sided specifications

If you are using one sided specifications, use the following formulas to determine the Cp:

Upper specification:

ppu formula

Lower specification:

ppl formula

Ppk

ppk formula

Where:

Zmin is the smaller of Zupper and Zlower.

Using sigma of the individuals:

z upper formula

z lower formula

Pr

pr formula

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