Cpk

The Cpk-Index (Critical Process Capability; k: “Katayori”, Japanese for bias) compares the distance from the process center to the nearest Specification Limit (how the process should be) to the process spread (how it is). The short-term standard deviation...

Cp

The Cp-Index (Process Capability) compares the tolerances of the process (how it should be) to the process spread (how it is). The short-term standard deviation sST is calculated using short term data, usually 25-50 samples within a short time frame – i.e. days....