Use
Control limits are used to detect signals in process data that indicate that a process is not in control and, therefore, not operating predictably. A signal is defined as any single point outside of the control limits. A process is also considered out of control if there are seven consecutive points, still inside the control limits but on one single side of the mean.
For normally distributed statistics, the area bracketed by the control limits will on average contain 99.73% of all the plot points on the chart, as long as the process is and remains in statistical control. A false-detection rate of at least 0.27% is therefore expected.
Read more about this topic: Control Limits
Famous quotes containing the word use:
“... it is use, and use alone, which leads one of us, tolerably trained to recognize any criterion of grace or any sense of the fitness of things, to tolerate ... the styles of dress to which we are more or less conforming every day of our lives. Fifty years hence they will seem to us as uncultivated as the nose-rings of the Hottentot seem today.”
—Elizabeth Stuart Phelps (1844–1911)