Process capability for continuous data

- Imagine a house with a garage, perhaps it's yours.…Is your car capable of entering the garage safely…without hitting either side of the garage doorway?…Yes.…Why?…Well, I know it's obvious…but it's because the width of the doorway…is wider than the width of the car.…Now, imagine your car is a process.…And the width of your car represents…a natural process spread of variation.…Looking at the garage doorway,…visualize that the lower and upper specification limits…are left and right edges of the doorway.…

The width of the car or the process spread,…in our analogy, can fit in…because it is narrower than the specification width.…But what if the process was as wide as a school bus?…Then it wouldn't be capable of going through the doorway.…How capable the car, the bus, or the process…is in meeting the specification width…is called potential process capability or CP.…For a normal curve,…the process spread is six standard deviations.…

Three to the left and three to the right side of the mean.…When CP is equal to or greater than one,…