5 Whys

5 Whys Analysis

For the problem stated by the user (or the current bug/issue), drill down through 5 layers of "why."

Process

1. State the observable problem
2. Ask "Why?" and answer with evidence (file paths, logs, code, not guesses)
3. Repeat 4 more times, each time asking why the previous answer is true
4. The 5th answer is usually the root cause

Rules

• Every answer MUST cite evidence: file path, line number, log output, or DB state
• If an answer is a guess, say so and verify before proceeding
• Stop early if root cause is obvious before layer 5
• Go past 5 if still not at root cause

Output Format

5 WHYS - [problem]

1. WHY: [observable problem]
   BECAUSE: [answer + evidence]

2. WHY: [why is #1 true?]
   BECAUSE: [answer + evidence]

3. WHY: [why is #2 true?]
   BECAUSE: [answer + evidence]

4. WHY: [why is #3 true?]
   BECAUSE: [answer + evidence]

5. WHY: [why is #4 true?]
   BECAUSE: [answer + evidence]

ROOT CAUSE: [the real thing to fix]
FIX:        [what to change, where]
SYSTEMIC:   [is this a one-off or pattern? if pattern, what prevents recurrence?]