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| Criterion |  Operations 8D Problem Solving |  UX Research User Interviews |  Operations 5 Whys |  Operations Root Cause Tree Analysis |
|---|---|---|---|---|
Purposedifferent | For an acute quality or delivery problem, the method structures immediate protection and root cause work together. It keeps the situation stable while the actual cause is investigated cleanly. | When teams derive needs only from assumptions and real motives are missing, user interviews give direct access to behavior and meaning. Conversations from the target group's everyday life make patterns, tensions, and open questions solidly visible. | 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 problem with several suspected causes, the method builds a causal structure instead of a mere list. It makes visible how causes connect and where the strongest points of leverage lie. |
Complexitydifferent | High | Low | Low | Medium |
Timedifferent | 1-6 Wochen | 30–60 min per interview | 15-30 min | 1-3 h |
Participantsdifferent | 4-10 | 1 participant per interview | 2-6 | 2-8 |
Formatdifferent | Workshop + async | Workshop + async | Workshop | Workshop |
Outputdifferent | 8D Report, Containment Plan, Root Cause Evidence, Corrective Action Plan | Interview Notes, Themes, Insight Summary | Root cause notes, Countermeasures | Cause Tree, Evidence Notes, Countermeasures |
Tagsno overlap | QualityProblem solvingRoot cause | QualitativeResearchCustomerDiscovery | Root causeIncidentLeanProblem solving | Root causeTreeIncidentQuality |