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| Criterion |  UX Research User Interviews |  Operations 5 Whys |  Operations Causal Factor Analysis |  Operations 8D Problem Solving |
|---|---|---|---|---|
Purposedifferent | 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 an event with a complicated course, the method breaks down the contributing factors along the timeline. It shows how conditions, decisions, and reactions together produce a course of events. | 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. |
Complexitydifferent | Low | Low | High | High |
Timedifferent | 30–60 min per interview | 15-30 min | 2-6 h | 1-6 Wochen |
Participantsdifferent | 1 participant per interview | 2-6 | 3-10 | 4-10 |
Formatdifferent | Workshop + async | Workshop | Workshop + async | Workshop + async |
Outputdifferent | Interview Notes, Themes, Insight Summary | Root cause notes, Countermeasures | Event Timeline, Causal Factor Chart, Cause List, Corrective Actions | 8D Report, Containment Plan, Root Cause Evidence, Corrective Action Plan |
Tagsno overlap | QualitativeResearchCustomerDiscovery | Root causeIncidentLeanProblem solving | CausalityIncidentRoot causeTimeline | QualityProblem solvingRoot cause |