Library skill · Thinkers' principles
Ohno-style 5 whys root-cause analysis
Finds the root cause of a problem with the 5 whys Taiichi Ohno illustrated: a measured gap, a chain of whys with evidence at each step, and a fix for the cause, not the symptom. Use it when an incident, defect or missed delivery needs a root cause.
Not affiliated with or endorsed by Taiichi Ohno or their companies. About these principles: Taiichi Ohno's ideas, explained.
AI skill
Have your AI find the root cause of a problem
14 days free · No card needed
Works in Claude, ChatGPT, and coding agents. On Team and Business, this library skill in your pod updates itself when we improve it.
When to use it
- An incident, defect or missed delivery needs a root cause
- The same problem keeps coming back after it was fixed
What you give it
- The problem and the standard it missed
- Logs, timelines and records
- What has been tried
- Who can confirm missing facts
What you get
A why-chain table with evidence per step, a read-back check, the root cause, containment and root-cause countermeasures with owners, and how you'll know it worked.
How it works
- State the problem as a gap
- Ask the first why
- Keep asking (principle 1)
- Check each link
- Stop at the root (principle 2)
- Set countermeasures (principle 3)
- Name an owner, a date and a check
Example
What you give it
Online shop. Last week 12 of 140 orders shipped a day late. We promise same-day dispatch for orders before 15:00. The packer says the label printer jammed several afternoons. Labels are printed in one batch at 14:30. The printer's last service was 18 months ago; the manual says every 6 months. Nobody owns the printer.
What you get back (the start of it)
These are principles Taiichi Ohno described publicly. Not affiliated with or endorsed by Taiichi Ohno or their companies.
The chain
| # | Why? | Because | Evidence |
|---|---|---|---|
| 1 | Why did 12 orders ship late? | Labels weren't printed in time | Packer's account |
| 2 | Why weren't labels printed in time? | The printer jammed during the 14:30 batch | Packer's account [check: printer error log] |
| 3 | Why did it jam? | It is 12 months past its service interval | Service record; manual says every 6 months |
| 4 | Why was the service missed? | Nobody owns the printer, so nobody books it | Input: "Nobody owns the printer" |
Root cause
The label printer has no owner, so its maintenance never gets scheduled; a single 14:30 batch turns any jam into late orders.
The rest of this output, the full steps and the checks the AI runs before it answers are in your pod once you add the skill.
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Changelog
- v1.0.1 · · Example output now opens with the attribution and not-affiliated lines, as the skill's own checks require.
- v1.0.0 · · First release.
Sources
- 5 Whys - Lean Enterprise Institute lexicon (read 2026-11-04)
- Toyota Production System - Toyota Motor Corporation (read 2026-11-04)