It’s human nature to feel good about effecting positive change. Perhaps you have removed some unnecessary steps from a process and now it is easier to perform a task. Or you have modified the way that work was being done and now there is less rework. Maybe your team has agreed on a more effective way to communicate and share information among various working groups. It could be that you identified some “critical X’s” to control and now there is less variation in the process. In any case, making small improvements that have a large effect can produce a great deal of satisfaction. After all, this is why we invested time and effort – to become better at whatever we do. It’s time to celebrate!
Unfortunately, improvements can be temporary. After the team disbands, the process can revert back to the previous condition or people drift back to the old way of doing things. Without something to prevent this regression, it is only a matter of time before any improvements (and the associated benefits) are in the rear view mirror. In the Lean Six Sigma world, the tool that is most often used to maintain the gains is a Control Plan. It is the centerpiece of the “C” step in the DMAIC methodology. A control plan should be used whenever you want to keep hard-won improvements in place.
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Regardless of how the improvements were made, you need to consider what it will take to keep the performance at the improved level. Click on the link below to view a control plan template. Even if you do not use a detailed plan like this one, you will need to consider how to monitor the process until the new methods and controls are firmly embedded in the new way of performing work.
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Once a control plan is written, approved, and communicated, the work is still not completed. The only way to assure that the control plan is being followed is to periodically perform an audit. Here are some guidelines for preparing and conducting control plan audits.
- All improvement projects should have a control plan.
- Any project that has been completed for at least six months is eligible for auditing.
- Set a goal to conduct a minimum of two audits per black belt per quarter.
- A black belt can set up a meeting with the process owner to review the existing control plan. To promote impartiality, the auditor should be a belt who was not involved with the original project as either a leader or a mentor.
As part of the review, the black belt and the process owner can use the following criteria to determine if the control plan should be updated or revised:
Is the process the same as when the control plan was created?
Are the measurements for X’s and Y still being taken?
Are there at least 2, but no more than 4 inputs in the control plan?
Has the Y metric remained at the post-project improvement level?
Are charts, dashboards, or other visual indicators current and being used?
Are the associated plan documents available, current, and being used?
Are the decision rules and corrective actions still relevant?
Have mistake-proofing principles been considered to strengthen the control?
Experience tells us that without a periodic audit, the process will slip back to the previous performance level about half the time. Indeed, it is a good thing when the audit uncovers a weakness in the control plan. This means that we can make the plan more effective. With an effective control plan, we will be more likely for the improvements to remain in place. Remember that the objective of a control plan audit is not to find fault, but rather to determine the easiest way to maintain the gains – so that we can advance the ball toward an even higher level of achievement!
Box and Luceno, Statistical Control by Monitoring and Feedback Adjustment, Wiley, 1997. ISBN 9780471190462.