Common cause

natural, random variation

The many small, always present sources of variation that together form the natural spread of a stable process. Reducing common-cause variation requires changing the process itself, not reacting to single points.

Calculate it

Process Capability & Control Charts: Cp, Cpk, Pp, Ppk, PPM and confidence intervals with X-bar/R, X-bar/S or I-MR charts and all 8 Nelson rules.

Related terms

• Special cause: assignable cause of variation