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Describe the observed problem separately from the explanation
A customer report may describe an interruption, error or failed part. Record the symptoms, equipment/version, use, timing and what was actually observed. A proposed cause belongs in a different field until the evidence supports it.
The American Society for Quality (ASQ) describes root-cause analysis as a set of approaches for investigating causes within a wider improvement process. Its guidance does not make a particular analysis duration, method or result mandatory for this business.
The same complaint count can describe different exposure
Fictional example: Version 1 has sixty units in service and complaints concerning three distinct units. Version 2 has twenty units in service and complaints concerning three distinct units. The simple proportions are 3/60 = 5% and 3/20 = 15%. Raw complaint counts alone hide that difference.
These are not defect rates or a valid statistical comparison by themselves. Age, operating hours, customer conditions, reporting and repeat complaints can differ. The figures show a question to investigate; they do not prove Version 2 caused the reports.
| Fictional version | Units in service | Distinct units with a complaint | Simple proportion |
|---|---|---|---|
| Version 1 | 60 | 3 | 5% |
| Version 2 | 20 | 3 | 15% |
Show the evidence connecting the action to the problem
Ask what changed, which explanation the evidence supports and what result the qualified team expects from the proposed correction. Define the check that would show the problem has been addressed, with an owner and a review point.
A closed ticket or replacement shipment can record work without establishing that the cause was removed. Watch for recurrence, new problems and differences between affected installations. Do not invent a zero-failure promise or a standard acceptable complaint percentage.
Keep safety and external duties on a separate track
Actual product-safety or other reportable information needs qualified assessment under the applicable rules; do not wait for an internal investigation to finish by default. The linked product-safety guide explains one researched Consumer Product Safety Commission (CPSC) scope, not every industry’s duties.
For the owner, the preparation output is a controlled record of the problem, evidence, action, verification and remaining uncertainty. Use it to decide whether to change the design, supplier, training, service scope or further investigation.
Scope
- Original fictional proportions and a quality-investigation framework. No cause, product defect, acceptable complaint rate, safety-reporting deadline or effective corrective action is established for a real product.
Next step
Use Management dependence to assign investigation, corrective-action approval and follow-up ownership. Keep customer complaints and technical evidence in the authorised quality system.
Sources & review notes
American Society for Quality
Passage, dates and research notes
professional-guidance · Definition, approaches and conducting root-cause analysis
Read the public method page. Used narrowly for evidence-based causal investigation within a wider improvement process. No fixed investigation duration, guaranteed result or required method is adopted.
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