Question

how do we know that process is in out of control or not by just looking at lower control limit and upper limit ? please give the exemple as well

Answer 1

In order to know whether the given process is under control or out of control by just analyzing the lower (LCL) and upper control limits (UCL), we should check whether the all the sample values are falling in the range of (LCL, UCL). If yes, then we can say that the process is under control. If the values fall outside this range, then we can say that the process is out of control.

For example,

If the sample values are 10.50, 10.20, 11.30, 10.75, 9.82, 11.05, 11.20, 10.64, 9.90, 11.00

and the LCL = 9.30, UCL = 11.30

Since all the values lie between (LCL, UCL), then we can say that the process is under control.