Imported from jabrena/plinth (skills/022-root-cause-analysis/SKILL.md). Install upstream with npx skills add jabrena/plinth --skill 022-root-cause-analysis. Copyright stays with the author (Apache-2.0).

Root Cause Analysis

Guide the identification of root causes, not symptoms, for a framed problem, using Five Whys, Fishbone (Ishikawa), Current Reality Tree, and constraint identification. This is an interactive SKILL.

What is covered in this Skill?

• Five Whys for a linear causal chain from a symptom to a root cause
• Fishbone (Ishikawa) for categorized candidate causes across multiple dimensions
• Current Reality Tree for interconnected causes and effects with a small number of core problems
• Constraint identification for the limiting factor holding the current state in place
• Choosing the technique(s) proportionate to the problem's complexity
• Feeding root-cause findings into 023-assumption-analysis and the remaining Functional Specification lenses

Constraints

Distinguish root causes from symptoms before recommending a fix. When this technique is orchestrated by another workflow, the orchestrator owns clarifying-question sequencing; when applied standalone, ask directly.

• MUST read references/022-root-cause-analysis.md before applying Root Cause Analysis guidance
• MUST distinguish a symptom (an observed effect) from a root cause (the condition that produces it)
• MUST apply Five Whys as a chain of "why" questions grounded in evidence from the problem frame, not assumption
• MUST apply Fishbone to organize candidate causes into categories (for example people, process, technology, environment) when more than one causal dimension is plausible
• MUST apply Current Reality Tree when multiple symptoms may share one or a small number of core problems connected by cause-effect relationships
• MUST identify the constraint limiting the current state, not only the most visible cause
• MUST NOT invent a root cause when the available evidence is vague or ambiguous; flag the gap for a clarifying question instead

When to use this skill

• Find the root cause of this problem
• Apply Five Whys to this issue
• Build a Fishbone diagram for this problem
• Use Current Reality Tree to connect these symptoms
• Identify the constraint limiting the current state
• Draft the Root Cause Analysis section of a Functional Specification

Workflow

1. Read the Reference

Read references/022-root-cause-analysis.md, then identify the symptom(s) evidenced by the problem frame.

2. Apply Five Whys

Chain "why" questions from the symptom toward an evidenced root cause, stopping when further "why" steps would require guessing.

3. Apply Fishbone When Multiple Dimensions Are Plausible

Organize candidate causes into categories when more than one causal dimension (people, process, technology, environment) is plausible.

4. Apply Current Reality Tree When Symptoms Interconnect

Connect multiple symptoms to a small number of shared core problems through cause-effect relationships when the symptoms appear related.

5. Identify the Constraint

Name the constraint limiting the current state, distinct from the most visible or most recently reported cause.

6. Report the Root Cause Findings

Report findings using Five Whys, Fishbone, Current Reality Tree, and the identified constraint, and flag any finding left open pending a clarifying answer.

Reference

For detailed guidance, examples, and constraints, see references/022-root-cause-analysis.md.