Quality defect hypothesis tree
A quality defect hypothesis tree organizes an investigation around evidence instead of opinion. It starts with the defect-rate change and splits the likely causes into materials, equipment settings, process execution and inspection. Each terminal branch says what to compare or observe next. Quality engineers can use it in a containment meeting to divide evidence-gathering work, then remove branches that do not explain the data. It works best when the root condition is stated precisely by product, lot and time period.
Open it in the AI editor with a prompt pre-filled — keep what works, change what doesn't.
Scenario
A manufacturing team investigates an increase in a measured product defect.
Key decisions
- Validate the signal: Confirm classification and sampling before acting.
- Check materials: Compare affected lots with certificates and samples.
- Check settings: Align the event timeline with parameter changes.
- Check process: Observe work steps and inspection practice.
When to reuse this
Use for an initial cross-functional investigation before selecting corrective action.
Frequently asked questions
How is this different from a fishbone diagram?
Can several branches be true?
What should the root contain?
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