For a process such as this to be in statistical control only

For a process such as this to be \"in statistical control,\" only random patterns of points should appear on the control chart. The process is \"not in statistical control\" when any non-random patterns appear on the chart. Three commonly used tests or rules for signaling that a process may not be in statistical control are:

Using these three rules, identify which (if any) of the rules gives an \"out of control\" signal, and indicate the subgroup number at which the signal is first given.

Solution

Rule 1: subgroup number 20 fall outside the low chart\'s control limit

Rule 2: Subgroup number 11 to 19 are on the same side of the chart\'s centerline

Rule 3: No.

So it is out of control