Root Cause Tool
Build the why chain
Approach: problem -> why 1 -> why 2 -> why 3 -> why 4 -> why 5
Write the symptom, not the assumed cause. Example: “Connector seating failures increased on final test after the weekend PM on Line 3.”
Apps / Root Cause Analysis
Lean 5-Why Root Cause Tool
Start with a clear problem statement, answer each why in sequence, and let the tool carry the chain forward until you reach a likely root cause worth verifying in the process.
Instructions
How to use this app
- Describe the problem as an observed symptom, not as a guessed cause.
- Click `Start 5-Why` to generate the first why question from that problem statement.
- Answer each why in plain operational language, then generate the next why from that answer.
- When the chain reaches a cause that feels fundamental, click `Mark as root cause` on that step.
- Take the selected cause back to the process and verify it with evidence, observation, traceability, or controlled testing.
This app helps structure thinking. It does not prove causation by itself. A real root cause still needs engineering and process verification before corrective action is finalized.