Calculated using customer $($designer$)$ specification and the process STD$.$

Used to find the proportion of individual outputs $($products$)$ that would be accepted by the customer $($designer$)$ fall within specifications.

Uses Control$-$Limits which are calculated using process properties $-$ e$.$g$.,$ mean and STD$.$

Samples statistics $($e$.$g$.,$ average, percentage$)$ are compared to control$-$limits$.$

Applied to verify a process is stable $-$ in$-$control.