The process capability index <italic>C</italic> _{<italic>pk</italic>} is widely used when measuring the capability of a manufacturing process. A process is defined to be capable if the capability index exceeds a stated threshold value, e.g. <italic>C</italic> _{<italic>pk</italic>}4/3. This inequality can be expressed graphically using a process capability plot,...

A common practical situation in process capability analysis, which is not well developed theoretically, is when the quality characteristic of interest has a skewed distribution with a long tail towards relatively large values and an upper specification limit only exists. In such situations, it...