5-Why Root Cause Analysis

Goal

Identify and validate a systemic root cause through a structured, evidence-based Why chain that can be directly linked to a corrective action.

Required Execution Checklist

• Problem defined with measurable data (value vs. specification)
• Linear Why chain built — one cause path at a time, no branching
• Each Why supported by objective evidence (not opinion or "probably")
• Logical consistency verified — reversal check passed
• Systemic root cause identified (not "human error" or symptom)
• Root cause validated: reproducibility test + elimination test
• Output enables definition of corrective action (PCA or CAPA)

When to use