5M Fishbone Diagrams
Using the Six Sigma system, a structured course of action is invariably implemented. The process starts with the Define phase, followed by Measure, and then Analyze. After Analysis comes Improve and Control. A key tool employed in the Measure phase is the fishbone diagram. A fishbone diagram displays the range of variables, or underlying causes, bringing about the problem under assessment. Analysis usually happens concurrently with Measurement Systems Analysis and calls for insight from a number of specialists.
5M Fishbone Diagram for Root Cause Analysis
5M Fishbone Diagram Approach
When working with a manufacturing environment, the following categories are frequently used:
- Measurement - including using measuring devices from the six sigma methodology to identify source causes and defects under that scope.
- Man - including those sources caused by people input within a specific step or work stream. Often, brainstorming activities and conversations help identify inputs within this category.
- Machine - including sources generated from machines used in the environment. Determining if one or more machines generate a significant portion of defects can be beneficial for locating the defect source.
- Method - providing an opportunity to review procedures used in the organization. At times, a procedural change may reduce the number of defects or help identify problems.
- Material - including any raw materials or other pieces requiring quality review during the process. At times, material used in the work stream may be the cause of defects identified by the end of the manufacturing process.
- Environment - including those external factors possibly affecting quality. Environmental causes should be analyzed to determine if they cause any negative effects or can be mitigated.
Fishbone Analysis
When starting the analysis, be sure to locate and document the inputs for the problem. Define the problem clearly and take the time to work through all potential factors. Nothing is out of scope during this phase. Inputs could be obvious or even unlikely or difficult to define. Consider using brainstorming sessions to identify a wide range of factors. Be aware that some may be subjective while others are fully supported by facts, data, or charts, including Pareto diagrams.
Pulling together the list of inputs requires full engagement from a wide variety of experts. The group should include representation from all impacted departments or processes. Once this begins, potential improvements to the service, product, or process may begin.
As identification of inputs occurs, the fishbone diagram develops as a result. While the look of the diagram should not be the focus, capturing all inputs is crucial. As an input is identified, additional causes could be identified. Each of these inputs and causes begin to branch from the larger bones. Throughout the process, identification may go several levels deep, which results in the shape. Each root cause is a small bone. If additional causes affect an input, it is not considered root.