Question

4. Which of the following is (are) true?
I. A production process that exhibits only random variability would be considered “out of control”.
II. If a point plotted on a control chart falls outside one of the control limits, this suggests the production process is “out of control”.
III. Assignable variation in a production process is completely random, and cannot be prevented.

		I and II
		II only
		III only
		I and III
		I only

Answer 1

I only

If a point is outside of the control limits in a control chart then it cannot be stated that the process is out of control, instead the fluctuation can be controlled. as it may cause a intermittent problem but not a long term issue.

Assignable variation can be managed in a process which is caused by a single factor resulting in distribution of non random results.

If a production process exhibits only random variability then the process can be state to be out of control because it is contained within a process which is unable to be determined and these fluctuations cannot be detected and eliminated at any instance.