User:HugeMallard/Humphries ratio

The Humphries Ratio

The Humphries Ratio is used to define whether a process is in control or out of control using the process capability (Cp) and process capability ratio (Cpk) of a process. It is used in 3-3 sigma quality measurements. The Humphries Ratio is defined as:

HR = Cp/Cpk

If the ratio is equal to 1 then the process is in control and the mean is on centre. If this value significantly deviates from 1 then the process may be in control but the mean is off centre.