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| Criterion |  Engineering Fault Isolation |  Operations 5 Whys |  Operations Failure Mode and Effects Analysis |  Operations Root Cause Analysis |
|---|---|---|---|---|
Purposedifferent | In technical failures, the visible symptom often gets mixed up with the actual cause. Fault Isolation narrows the fault space and progressively reduces which part of the system is truly affected. | For a single, hard-to-explain deviation, the method exposes the causal chain behind the visible symptom. It keeps the cause open until a controllable condition emerges instead of a mere description. | For a process, product, or service with noticeable failure risks, the method assesses possible failure modes in advance. It directs attention to combinations of occurrence, effect, and detectability. | When a problem keeps recurring and the cause stays unclear, the method exposes the underlying mechanism. It separates symptom, guess, and robust explanation from one another. |
Complexitydifferent | Medium | Low | High | Medium |
Timedifferent | 30-180 min | 15-30 min | 2-6 h | 1-4 h |
Participantsdifferent | 1-6 | 2-6 | 3-10 | 3-8 |
Formatdifferent | Workshop + async | Workshop | Workshop | Workshop + async |
Outputdifferent | Fault Isolation Map, Test Log, Excluded Hypotheses, Narrowed Fault Area | Root cause notes, Countermeasures | FMEA Table, Risk Priority, Mitigation Actions | Problem Statement, Cause Hypotheses, Confirmed Causes, Action Plan |
Tagsno overlap | TroubleshootingDiagnosisEngineering | Root causeIncidentLeanProblem solving | RiskQualityOperationsRoot cause | Root causeProblem solvingQualityIncident |