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Fishbone (Ishikawa) Diagram Template
A structured Excel worksheet organizing potential causes across the 6M categories, plus a cause investigation log so a brainstorm turns into a documented trail.
The Diagram tab lays out all six categories — Method, Machine, Material, Manpower, Measurement, and Environment — with room for potential causes and a column to flag likely root causes as the team narrows down. The Cause Log tab tracks which causes were actually investigated, by whom, and their final disposition.
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What Is Included in the Workbook
| Sheet | Purpose | What Teams Capture |
|---|---|---|
| How-To | Method guidance and orientation | How to run a 6M brainstorm and use the cause log |
| Diagram | Cause-and-effect worksheet | Effect statement, owner, date, and potential causes under each of the 6M categories |
| Cause Log | Investigation tracking register | Each brainstormed cause, who investigated it, findings, and disposition (confirmed, ruled out, needs more data) |
Key Features Inside the Template
All 6M Categories Pre-Built
Method, Machine, Material, Manpower, Measurement, and Environment are already laid out and labeled — no setup before the team can start brainstorming.
Likely Root Cause Flag
A dedicated column next to each cause lets the team mark standout candidates as the brainstorm narrows toward verification.
Investigation Trail, Not Just a Brainstorm
The Cause Log turns a one-time whiteboard session into a documented record of what was actually checked and what was found.
Dropdown-Controlled Disposition
Each logged cause's outcome is chosen from a fixed list — Confirmed, Ruled Out, Needs More Data — keeping the log consistent across contributors.
Best Use Cases
- Root cause brainstorming sessions during a DMAIC Analyze phase or Kaizen event
- Cross-functional problem-solving meetings needing a shared, visible cause structure
- Training new team members on structured cause-and-effect thinking
- Documenting the investigation trail behind a closed CAPA or 8D report
How to Use the Template Effectively
- Write a specific, observable effect statement — not a category of problem.
- Brainstorm causes under every category, even ones that feel less likely at first.
- Mark likely root causes only after the full brainstorm is complete, not as you go.
- Move flagged causes to the Cause Log and assign an owner to investigate each one.
- Update disposition as evidence comes in, rather than leaving causes open indefinitely.
Who Should Use This Template
- Quality engineers and team leads running structured root cause investigations
- Kaizen event teams brainstorming causes during the Focus phase
- Trainers teaching cause-and-effect thinking to new problem-solvers
Common Mistakes to Avoid
- Stopping the brainstorm after the first plausible-sounding cause is found
- Skipping categories that seem irrelevant without actually discussing them
- Never logging which causes were investigated, so the same ones get re-debated later
Related Guides and Tools
Read the Fishbone (Ishikawa) Analysis Guide
The full method, category definitions, and a worked example this template is built around.
Use the Fishbone (Ishikawa) Diagram Builder
Build and preview a fishbone diagram interactively in the browser before committing it to this file.
Read the 5-Why Root Cause Analysis Guide
Use 5-Why to drill deeper into any single cause flagged on this worksheet.
Fishbone (Ishikawa) Diagram Template Frequently Asked Questions
How many causes should each category have?
There's no fixed number -- some problems are dominated by one or two categories and others spread evenly across all six. The worksheet includes six rows per category as a starting point; add more rows if a category needs them.
What is the Cause Log tab for?
It tracks which brainstormed causes were actually investigated, who investigated them, what was found, and whether the cause was confirmed, ruled out, or needs more data.