Shewhart cycle
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The Shewhart cycle (also referred to as the Deming Cycle, after W. Edwards Deming) was named for Walter Shewhart, who discussed the concept in his Statistical Method from the Viewpoint of Quality Control book. It is the continuous improvement cycle of Plan, Do, Check, Act (PDCA).
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The FOCUS - PDCA Methodology
Some people expand PDCA to a nine-step process that incorporates a FOCUS stage before the PDCA cycle. These nine steps are:
- Find a process that needs improvement.
- Organize a team that knows the process.
- Clarify knowledge of the process by flowcharting or data collection.
- Uncover the underlying causes of variation or poor quality.
- Start the P-D-C-A cycle by choosing a single modification to the process.
- Plan a pilot to test the improvement.
- Do the improvement.
- Check that the process actually improved.
- Act to adopt, adjust or abandon the change.
The Joiner Seven Step Method
The Plan-Do-Check-Act cycle can (and should) be applied at all levels of improvement. However, it is useful to have a fuller, more detailed macro P-D-C-A that applies to the project as a whole. This provides us with:
- a framework with which we can visualize progress through a project,
- check-steps that allow us to see that we are not trying to proceed too quickly through part of the improvement process without having gained sufficient understanding,
- a means of documenting a project.
One useful framework to do this is the "7 Step Model", developed by Joiner Associates (Brian L. Joiner). As well as providing a disciplined framework for progressing through a project, the 7 Step model provides a good framework for documenting a project. The 7 Steps are:
STEP 1 Define Project Purpose and Scope
- Focus on strategically important problems
- Choose an appropriate project team and team leader
- Clarify the project mission
- Determine how much progress can be expected
- Formulate a framework and execution plan for the project
STEP 2 Current Situation
- Understand the present process
- Determine customer needs and expectations
- Flow chart the process
- Collect data to identify the real problem
- Standardize the process, if necessary
STEP 3 Cause Analysis
- Dig down for the root causes of the problem
- Identify the major potential causes
- Verify them with data, if possible
STEP 4 Solutions
- Choose between alternative solutions
- Keep solutions simple
- Identify barriers to implementing solutions
- Plan and make necessary changes (use PDCA)
STEP 5 Results
- Evaluate the solutions
- Collect data, to compare before and after improvement
- Compare results with what we expected
STEP 6 Standardization
- Standardize the new process
- Document the changes made
- Error proof the process
STEP 7 Future Plans
- Review what has been learned from this project
- Decide whether to continue with this project, or
- Close project, and move on to a more pressing project
See also
References
Shewhart, Walter Andrew (1939). Statistical Method from the Viewpoint of Quality Control. New York: Dover. ISBN 0486652327.
Shewhart, Walter Andrew (1980). Economic Control of Quality of Manufactured Product/50th Anniversary Commemorative Issue. American Society for Quality. ISBN 0873890760.
