Page 42 - Quality control of pharmaceuticals (07-PA 704)
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Control Charts
Even control charts in which all points lie between the control limits might suggest
that a process is out of control. In particular, the existence of a pattern in eight or
more consecutive points indicates a process out of control, because an obvious
pattern violates the assumption of random variability.
The first eight observations are below the center line, whereas the second seven
observations all lie above the center line. Because of prolonged periods where
values are either small or large, this process is out of control.
