Learning objective
By the end of this lesson, you can mark a causal chain by evidence status and recognise when to branch or switch methods.
Why it matters
Repeated questions can create a convincing story even when each answer is an assumption. The method becomes analytical only when links are verified.
Core concept: label every link
Use four statuses:
- verified — direct evidence supports the link;
- plausible — mechanism makes sense, evidence pending;
- contradicted — evidence conflicts with the claim;
- unknown — the team cannot yet explain the link.
Visual explanation
Worked example
Claim: reminders were wrong because support agents entered the wrong time.
Evidence: wrong times appear only after digital rescheduling, including bookings with no agent edit.
Status: contradicted.
The next question should not be “Why were agents careless?” It should test an alternative path, such as stale data after rescheduling.
Common mistake
Mistake: forcing one branch.
If both an incorrect configuration and an unclear instruction contributed, record both. Use an Ishikawa diagram when branches multiply.
Quick check
The team has no record supporting its third answer. What should it do?
A. Continue to the fifth why.
B. Mark it verified because experts agree.
C. Mark it plausible or unknown and collect evidence.
D. Choose the easiest corrective action.
Answer: C.
Practical prompt
Take an existing 5 Whys chain. Mark every link verified, plausible, contradicted or unknown. Identify the first point where evidence collection is required.
Summary
- Repetition does not create evidence.
- Causal chains can branch.
- Stop or switch methods when complexity exceeds the tool.
Next lesson
Continue to Ishikawa Diagram to organise multiple cause families.