How do we demonstrate continual improvement?
ISO 9000:2015 defines continual improvement as a recurring activity to increase the ability to fulfil requirements.
We cannot improve anything unless we know its present condition and this requires measurement and analysis to tell us whether improvement is both desirable and feasible. The first step is therefore to ensure objectives, targets or requirements exist for the performance of the product or process characteristics to be measured.
The second step is to measure performance and compare it with the target. If no output meets the requirements, action taken to achieve conformity is not an improvement action. This only puts the process back to where it should have been in the first place. Eliminating special causes is not improvement but maintaining the status quo.
This leaves two areas where improvement is desirable - the reduction of common cause variation and the raising of standards. Once the process is producing conforming output, action taken to reduce common cause variation or to raise standards is improvement action and can be demonstrated by charts showing performance trends over time. (Note: Special cause variation is variation that can be assigned to a specific or special condition that does not apply to other events. Common cause variation is variation that is random caused by factors that are inherent in the system).