The Six Sigma ‘Control’ Phase
The Six Sigma “Control” phase accomplishes several goals. In this phase, the project team:
- Measures the process and uses statistics to demonstrate that the process capability has increased
- Documents the changes
- Establishes ongoing monitoring efforts
- Closes the project.
Document the Changes
Some call this activity “Document the Improvements”, but that can be misinterpreted as noting how much better the outputs have become thanks to the project. This activity is more about “project documentation”.
The first point is to revise the process map to reflect the implemented changes. Created in the “Improve” phase to illustrate the initial processes, it should now include the actual changes.
Further documentation may be required. These may include new instructions for operating the equipment; revised maintenance schedules; or updated procedures for ordering supplies or receiving customer requests.
Training is usually included to fully implement the revised processes. The ongoing monitoring efforts will also require staff training.
Establish Ongoing Monitoring Efforts
This is the most obvious and visible aspect of “Control”. The first step is to specify:
- What is to be measured
- How often will the measurements be taken
- What analysis should be performed
- Who should be notified of problems
- What response should be made to the problem notification
The measurements will probably be a subset of those established in the Measure phase. Why a “subset”? It is likely that this project has determined which metrics are most relevant to the problem under scrutiny; other metrics may not matter much, and be too costly or time-consuming to gather on an ongoing basis. The measurements should, however, be sufficient to determine whether the output is defective.
The discipline of Statistical Process Control is a useful tool for these measurements. By monitoring and analyzing the production process, assignable-cause variations can be noted and corrected.
This monitoring process should begin before the project is closed. The Six Sigma team should mentor the front-line workers to transfer the knowledge of how to perform the monitoring function.
A final task is to document “how to make changes” in the future, such as keeping the process map, procedures documents and monitoring processes in alignment when a process change is made. This is a candidate for the poka yoke, or “error avoidance”, approach. Try to design the change process so it is difficult to avoid touching each facet. An example would be an implementation checklist with a sign-off requirement. The checklist would include each type of documentation, and serves as a reminder that they are inter-related.
Close the Project
The major task is to return control fully to the department manager or process owner.
In addition, the project team may have further suggestions based on their observations but outside the scope of the original project charter. These may range from “quick fix” ideas through new Six Sigma projects.
The final reports should include an analysis of the project itself:
- Were the costs within budget?
- Did it meet the planned schedule?
- Is the problem solved?
Oskar Olofsson, 2011
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I am a Swedish-based Lean consultant, and the owner of the World-Class-Manufacturing.com web site.
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