The fishbone diagram, also called an Ishikawa or cause-and-effect diagram, is a common tool for identifying critical Xs: process parameters with the greatest effect on performance. It gives the team a visual representation of the factors contributing to a specific problem. It is used to:
- Ensure that all possible causes have been considered.
- Draw on the knowledge of process experts.
- Ensure that the actual problem has been identified.
- Identify and assess the impact of addressing each identified cause.
Below are an Ishikawa diagram template and a guide for scoring impact against ease of implementation. This example identifies six main categories: policies, procedures, people, environment, IT systems and measurement. Adjust the categories to suit your project.
| Potential Cause Categories | Effect |
|---|---|
| Policies Procedures People Environment IT Systems Measurement |
Problem statement |
| Ease of Implementation | High Impact | Low Impact |
|---|---|---|
| Easy | 1 | 2 |
| Difficult | 3 | 4 |
How Do I Create a Fishbone Diagram?
The cause-and-effect diagram is one of the simplest Lean Six Sigma tools. Hold a brainstorming session with a cross-functional team representing the entire process. Keep the team focused on the problem statement and list possible main drivers. A sparse diagram or empty branches may indicate a poor understanding of the problem or an unsuitable team. A category with many causes may be a good focus for data collection; some categories may legitimately remain empty. Once all possible causes have been identified, score them from 1 to 4 using the Impact vs. Ease of Implementation matrix.
Related Links:
- Lean Six Sigma Project Roadmap
- Measure
- Process Map
- What Is FMEA?
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Reference:
Lean Six Sigma, The McGraw-Hill 36-Hour Course, by Sheila Shaffie.
