A simple technique that is easy to misuse. How to keep root-cause analysis honest and evidence-based.
28 September 2026 · 1 min read
The Five Whys is often the first problem-solving tool people learn, and the first one they misuse. Asked carelessly, it produces a tidy story rather than a verified cause.
Start with a well-defined problem
A vague problem statement leads to vague answers. Describe what happened, where, when and how much — before asking why.
- State the observed deviation, not the assumed cause.
- Quantify it where possible.
- Agree on the statement with the people closest to the work.
Verify each answer
Every ‘because’ should be something you can check. If you cannot show evidence for a step, treat it as a hypothesis, not a link in the chain.
Go and see. The answer is rarely in the meeting room.— A common lean principle
Know when to stop
Stop when you reach a cause you can act on and that, if removed, would prevent recurrence. Sometimes that takes three whys; sometimes seven.
Illustrative sample article.