critical product measurements (CpK)

Definition

Statistical measurements of the process capability in terms of its design specifications (limits) and performance (variability). Used in quality control, CpK takes into account both accuracy (centering) and precision (dispersion) and helps determine the cause of failures and the need for changes in the product design, tooling, or the manufacturing process. Higher the CpK value, greater the indication that the process is consistently under control (is within limits). A CpK value of 1.33 is considered the minimum and, as it nears 2.0, the process approaches six sigma value meaning there are only 3.4 defective units out of one million produced.