AAOM Handbook

INTERNAL

AI.03 Process Changing due to Control Action? Context The first question to be asked when assessing process performance is whether the process is stable. A stable process is one that is performing consistently, that is, nothing unusual has happened and the process is not changing. A control chart is used to determine if a process is stable. If the control chart indicates that the process is unstable, that is, something unusual has happened or the process is changing, the question must be asked - is this due to the effects of a control action that has been taken or is there another special cause for the change? If the change is the beneficial result of a control action then complete or continue the action. If the change is the detrimental result of a control action then stop or reverse the action. If the change is due to another special cause then an immediate investigation is required. This task is to determine whether a process change is the result of a deliberate control action or some other cause. Purpose To decide if a process change is the result of a control action. Quantity One decision on the probable causes of a change in process stability. Quality Review current control actions to identify any that would produce the observed change in process stability. Confirm that a control action with the potential to produce the observed change has progressed to the extent that the change is expected. Examine any other data that will validate that the observed change is caused by the control action. Resources This task is completed by the person responsible for the process performance at the time a change in process stability is recognised. Time As soon as a change in process stability is recognised.

© McAlear Management Consultants 2007

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