Fishbone (Ishikawa) Cause and Effect Worksheet
A fishbone diagram sorts possible causes of one problem into categories so the team brainstorms widely before it narrows. This worksheet keeps the same logic in a table you can sort, vote on and export to Excel.
| Category (6M) | Possible cause | Sub-cause (why) | Evidence / how to verify | Team votes | Status | Owner | |
|---|---|---|---|---|---|---|---|
Write the problem statement (the effect) in the sheet title when you export. Vote with dots, then verify the top-voted causes with data before you act.
Link causes to ERP defect history
Optional: a quick review of how scrap, rework and supplier data can support each cause in your fishbone.
Optional. The tool and every export work without this. No spam.
How to use the worksheet
State one specific problem, such as 'bore diameter out of tolerance on 7% of parts'. Add rows by category, one cause per row, with the underlying 'why' in the sub-cause column. After the brainstorm, give each team member three to five votes and enter the totals. The evidence column is the most important: for each top cause, write the data or check that will confirm or rule it out. Update the status as you verify. Delete rows only after ruling them out so the record stays honest.
- One problem statement per worksheet
- One cause per row, with a why beneath it
- Vote first, verify second
- Mark causes as ruled out rather than deleting them
The 6M categories
Man covers skill, training and fatigue. Machine covers equipment condition, tooling and maintenance. Method covers procedures, setups and work instructions. Material covers raw material, components and supplier variation. Measurement covers gauges, calibration and sampling. Environment covers temperature, humidity, cleanliness and layout. Service and office processes often swap these for the 4P or 8P sets. Pick the set that fits and keep it consistent across projects so comparisons make sense.
Common mistakes
Teams often stop at the first plausible cause and never verify it. Another mistake is mixing symptoms with causes, such as writing 'scrap' as a cause of scrap. Brainstorming with only supervisors misses operator knowledge. Finally, a fishbone lists possibilities, not conclusions. Move the top-voted causes into a Pareto, a designed test, or a Gage R&R when measurement is suspect, and document the confirmed cause in the A3 or 8D.
Frequently Asked Questions
What is a fishbone diagram used for?
It is a brainstorming and organizing tool for root cause analysis. The problem sits at the head and possible causes branch off by category. It prevents the team from fixating on one cause and shows gaps in coverage.
Fishbone or 5 Whys?
Use a fishbone to explore many possible causes, then use 5 Whys to drill into each likely branch. They complement each other. The sub-cause column in this worksheet is where you record the why chain.
How many votes should each person get?
Three to five dots per person is common, and teams usually vote on the sub-causes they believe are most likely. Voting is a way to prioritize what to verify first, not proof that a cause is real.
Can I use it outside manufacturing?
Yes. Change the categories to fit, for example people, process, policy and platform for service work. The worksheet column is a select list, so export and rename if your categories differ.
If you want defect history from your ERP attached to each candidate cause, Netray can help connect the data.
Related Tools
A3 Problem Solving Report Template
A structured one-page report for a chronic OEE or quality problem, from background to follow-up, ready to print or share.
Quality & InspectionDefect Check Sheet Worksheet
Tally defect types by day, get row and column totals, and feed the counts into a Pareto chart. Exports to Excel.
Quality & InspectionGage R&R Data Collection Sheet
Record two-operator, two-trial measurements per part and get ranges, part means and an approximate repeatability estimate.
Quality & InspectionSIPOC Diagram Template
Fill-in SIPOC document with suppliers, inputs, process steps, outputs, customers and requirements. Exports to PDF, Word or Excel.
More Quality & Inspection tools
See all- Cpk Confidence Interval Calculator
- Pp Ppk Process Performance Calculator
- DPMO and Sigma Level Calculator
- X-bar and R Control Chart Limits Worksheet
- Control Chart Constants Table (A2, D3, D4, d2, c4)
- P Chart Control Limits Calculator
- Defect Pareto Analysis Worksheet
- DMAIC Project Charter Template
- SPC Control Plan Worksheet