Which one of the following rules is NOT used for identifying an out-of-control process?
1
A process is assumed to be out-of-control if a single point plots outside the control limits
2
A process is assumed to be out-of-control if there is a run of six or more consecutive points steadily increasing or decreasing
3
A process is assumed to be out-of-control if nine or more consecutive points fall to one side of the centre line
4
A process is assumed to be out-of-control if two or more consecutive points fall beyond the 1σ limit on the same side of the centre line