rca-classical-methods
Classical root cause analysis techniques for quality improvement and incident investigation. Covers 5 Whys (with Card's 2017 critique and boundary conditions), Ishikawa/fishbone diagrams, Fault Tree Analysis (FTA), Failure Modes and Effects Analysis (FMEA), Cause Mapping, and Doggett's method-selection framework. Use when investigating a failure, running a post-incident analysis, building a fishbone, calculating fault tree cut sets, running an FMEA pass, or deciding which classical technique fits the problem. Not suitable alone for complex socio-technical failures — escalate to rca-systems-the
npx skills add majiayu000/claude-skill-registry --skill rca-classical-methods --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# Classical RCA Methods Classical root cause analysis techniques are the inherited toolkit of quality and reliability engineering. They are best understood as a *family* with different strengths and known failure modes — not as interchangeable recipes. This skill teaches when to reach for each one, how to run it rigorously, and when to stop and escalate to a more capable method. ## The six techniques at a glance | Technique | Origin | Best for | Known weakness | |---|---|---|---| | **5 Whys** | Toyota Production System (Sakichi Toyoda, Taiichi Ohno) | Simple, linear, single-cause problems on the shop floor | Forces single pathway, non-reproducible across analysts (Card 2017) | | **Fishbone (Ishikawa)** | Kaoru Ishikawa, 1960s | Brainstorming categorized contributing factors | Can produce unwieldy diagrams, no intrinsic prioritization | | **Fault Tree Analysis (FTA)** | Bell Labs, Minuteman ICBM (1960s) | Safety-critical systems with quantifiable failure probabilities | Requires known failure modes upfront, expensive to build | | **FMEA** | U.S. military (MIL-P-1629, 1949); automotive (AIAG) | Proactive design review, risk prioritization via RPN | RPN ordinal-math is statistically u
- The six techniques at a glance
- Technique 1 — The 5 Whys (with boundary conditions)
- What it is
- Why it often fails
- When you may still use it
- Running it rigorously
- Technique 2 — Fishbone / Ishikawa diagram
- The category spines
- Construction steps
- Evidence from Barsalou & Starzynska (2023)
- Technique 3 — Fault Tree Analysis (FTA)
- Notation
- Quantitative FTA
- When to use
What does the rca-classical-methods skill do?
Classical root cause analysis techniques for quality improvement and incident investigation. Covers 5 Whys (with Card's 2017 critique and boundary conditions), Ishikawa/fishbone diagrams, Fault Tree Analysis (FTA), Failure Modes and Effects Analysis (FMEA), Cause Mapping, and Doggett's method-selection framework. Use when investigating a failure, running a post-incident analysis, building a fishbone, calculating fault tree cut sets, running an FMEA pass, or deciding which classical technique fits the problem. Not suitable alone for complex socio-technical failures — escalate to rca-systems-the
How do I install it?
Run `npx skills add majiayu000/claude-skill-registry --skill rca-classical-methods --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From majiayu000/claude-skill-registry, a repository with 534 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.