name: root-cause-analysis description: Problem solving using Fishbone (Ishikawa) diagrams and 5 Whys technique. Identifies root causes systematically and recommends corrective actions. allowed-tools: Read, Glob, Grep, Task, Skill

Root Cause Analysis

Systematic problem solving using Fishbone (Ishikawa) diagrams and 5 Whys technique. Identifies true root causes and recommends effective corrective actions.

What is Root Cause Analysis?

Root Cause Analysis (RCA) is a structured approach to identify the fundamental cause(s) of problems, rather than addressing symptoms. Effective RCA prevents problem recurrence.

Approach	Focus	Best For
Fishbone (Ishikawa)	Brainstorming all potential causes by category	Complex problems with multiple potential causes
5 Whys	Drilling down through cause chains	Problems with linear cause-effect relationships
Combined	Fishbone to identify, 5 Whys to drill down	Comprehensive root cause identification

Framework 1: Fishbone (Ishikawa) Diagram

What is a Fishbone Diagram?

A Fishbone diagram (also called Ishikawa or cause-and-effect diagram) organizes potential causes into categories, resembling a fish skeleton with the problem as the "head."

        ┌─────────────────────────────────────────────────────────┐
        │                                                         │
  Man ──┼──┐                                         ┌──┼── Method
        │  │                                         │  │
        │  └─────────────────────┐   ┌───────────────┘  │
        │                        │   │                  │
        │                        ▼   ▼                  │
        │                    ┌─────────┐                │
        │                    │ PROBLEM │                │
        │                    └─────────┘                │
        │                        ▲   ▲                  │
        │  ┌─────────────────────┘   └───────────────┐  │
        │  │                                         │  │
Machine ┼──┘                                         └──┼── Material
        │                                               │
        │                                               │
Measurement ────────────────────────────────────────────── Mother Nature
        │                                               │
        └───────────────────────────────────────────────┘

The 6M Categories

Category	Also Called	Example Causes
Man	People, Personnel	Training, skills, fatigue, communication
Machine	Equipment, Technology	Hardware, software, tools, maintenance
Method	Process, Procedure	Workflow, documentation, standards
Material	Inputs, Data	Raw materials, components, information quality
Measurement	Metrics, Inspection	Calibration, accuracy, data collection
Mother Nature	Environment	Temperature, humidity, regulations, market

Alternative Category Sets

Domain	Categories
Manufacturing (6M)	Man, Machine, Method, Material, Measurement, Mother Nature
Service (8P)	Product, Price, Place, Promotion, People, Process, Physical Evidence, Productivity
Software (5S)	Systems, Skills, Suppliers, Surroundings, Safety
Custom	Define categories relevant to your domain

Fishbone Workflow

Step 1: Define the Problem

## Problem Statement

**Problem:** [Clear, specific, measurable description]
**Impact:** [Quantified impact - cost, time, quality, safety]
**When Discovered:** [Date/time]
**Where:** [Location, system, process]
**Frequency:** [One-time / Recurring / Intermittent]

Good problem statements:

✅ "Customer orders delayed by 3+ days increased 40% in Q4"
✅ "Production line 3 defect rate rose from 2% to 8% in November"
❌ "Things are slow" (too vague)
❌ "The system is broken" (not measurable)

Step 2: Assemble the Team

Include people with direct knowledge:

Role	Contribution
Process Owner	Overall accountability
Front-line Workers	Direct observation and experience
Subject Matter Experts	Technical knowledge
Customer Representative	Impact perspective
Facilitator	Guide the process

Step 3: Brainstorm Causes by Category

For each category, ask: "What in this category could cause the problem?"

## Cause Brainstorming

### Man (People)
| Potential Cause | Evidence | Likelihood |
|-----------------|----------|------------|
| Insufficient training | New hires 60% of errors | High |
| Fatigue (overtime hours) | Errors peak after 8 hours | Medium |
| Communication gaps | Handoff errors documented | High |

### Machine (Equipment)
| Potential Cause | Evidence | Likelihood |
|-----------------|----------|------------|
| Aging equipment | Machine 7 has 40% of failures | High |
| Software bugs | Version 2.1 introduced defects | Medium |

### Method (Process)
| Potential Cause | Evidence | Likelihood |
|-----------------|----------|------------|
| Unclear procedures | 3 different approaches observed | High |
| Missing quality check | No verification step documented | High |

### Material (Inputs)
| Potential Cause | Evidence | Likelihood |
|-----------------|----------|------------|
| Supplier quality issues | Incoming defect rate up 15% | Medium |
| Specification ambiguity | Multiple interpretations possible | Low |

### Measurement (Metrics)
| Potential Cause | Evidence | Likelihood |
|-----------------|----------|------------|
| Inaccurate sensors | Calibration overdue | Medium |
| Wrong metrics tracked | Leading indicators missing | Low |

### Mother Nature (Environment)
| Potential Cause | Evidence | Likelihood |
|-----------------|----------|------------|
| Seasonal demand spike | Q4 always highest volume | High |
| Regulatory changes | New requirements in October | Low |

Step 4: Identify Most Likely Root Causes

Prioritize based on:

Criterion	Question
Evidence	Is there data supporting this cause?
Frequency	Does this cause relate to problem frequency?
Correlation	Does the cause timing match problem timing?
Control	Can we test or eliminate this cause?

Step 5: Validate Root Causes

For each high-likelihood cause:

## Root Cause Validation

| Cause | Validation Method | Result | Confirmed? |
|-------|-------------------|--------|------------|
| Insufficient training | Compare error rates by tenure | New hires 3x error rate | ✅ Yes |
| Aging equipment | Analyze failures by machine | Machine 7: 40% of all failures | ✅ Yes |
| Unclear procedures | Review documentation | 3 conflicting SOPs found | ✅ Yes |

Fishbone Output Format

## Fishbone Analysis: [Problem]

**Date:** [ISO date]
**Facilitator:** rca-analyst
**Team:** [Participants]

### Problem Statement
[Clear, specific, measurable problem]

### Impact
[Quantified business impact]

### Cause Analysis

#### Man (People)
- [Cause 1] - Evidence: [X] - Status: Confirmed/Suspected
- [Cause 2] - Evidence: [X] - Status: Confirmed/Suspected

#### Machine (Equipment)
- [Cause 1] - Evidence: [X] - Status: Confirmed/Suspected

#### Method (Process)
- [Cause 1] - Evidence: [X] - Status: Confirmed/Suspected

#### Material (Inputs)
- [Cause 1] - Evidence: [X] - Status: Confirmed/Suspected

#### Measurement (Metrics)
- [Cause 1] - Evidence: [X] - Status: Confirmed/Suspected

#### Mother Nature (Environment)
- [Cause 1] - Evidence: [X] - Status: Confirmed/Suspected

### Confirmed Root Causes
| # | Root Cause | Category | Evidence | Contribution |
|---|------------|----------|----------|--------------|
| 1 | [Description] | [6M] | [Data] | [% of problem] |

### Recommended Actions
| # | Action | Addresses | Owner | Due Date |
|---|--------|-----------|-------|----------|
| 1 | [Corrective action] | Root Cause #1 | [Name] | [Date] |

Fishbone Mermaid Diagram

flowchart LR
    subgraph Man["👤 Man"]
        M1[Training gaps]
        M2[Communication issues]
    end

    subgraph Machine["⚙️ Machine"]
        MA1[Aging equipment]
        MA2[Software bugs]
    end

    subgraph Method["📋 Method"]
        ME1[Unclear procedures]
        ME2[Missing QC step]
    end

    subgraph Material["📦 Material"]
        MT1[Supplier quality]
        MT2[Specification issues]
    end

    subgraph Measurement["📊 Measurement"]
        MS1[Sensor accuracy]
        MS2[Wrong metrics]
    end

    subgraph Environment["🌍 Environment"]
        E1[Seasonal demand]
        E2[Regulatory changes]
    end

    M1 & M2 --> Problem
    MA1 & MA2 --> Problem
    ME1 & ME2 --> Problem
    MT1 & MT2 --> Problem
    MS1 & MS2 --> Problem
    E1 & E2 --> Problem

    Problem[❌ PROBLEM:<br/>Customer delays<br/>increased 40%]

    style Problem fill:#f99,stroke:#900

Framework 2: 5 Whys

What is 5 Whys?

5 Whys is an iterative interrogative technique that drills down from symptoms to root causes by repeatedly asking "Why?" (typically 5 times, but may be fewer or more).

Key Principle: Each answer becomes the subject of the next "Why?"

5 Whys Workflow

Step 1: State the Problem

## 5 Whys Analysis

**Problem:** [Specific problem statement]
**Date:** [ISO date]
**Analyst:** 5whys-analyst

Step 2: Ask Why Iteratively

### Why Chain

**Problem:** The website crashed during the product launch.

**Why 1:** Why did the website crash?
→ The server ran out of memory.

**Why 2:** Why did the server run out of memory?
→ The application had a memory leak.

**Why 3:** Why did the application have a memory leak?
→ The new feature wasn't properly tested under load.

**Why 4:** Why wasn't the new feature tested under load?
→ We don't have load testing in our CI/CD pipeline.

**Why 5:** Why don't we have load testing in CI/CD?
→ It was never prioritized when the pipeline was set up.

**Root Cause:** Load testing was not included in CI/CD pipeline during initial setup.

Step 3: Validate the Root Cause

Validation Check	Question	Pass?
Specific	Is the root cause specific and actionable?	☐
Systemic	Does addressing this prevent recurrence?	☐
Controllable	Can we actually fix this?	☐
Chain Valid	Does each why-answer logically lead to the next?	☐

5 Whys Best Practices

Do	Don't
✅ Focus on process/system causes	❌ Blame individuals
✅ Base answers on facts and evidence	❌ Speculate without data
✅ Keep asking until actionable root found	❌ Stop at symptoms
✅ Document the chain for future reference	❌ Accept "human error" as root cause
✅ Consider multiple parallel chains	❌ Assume single root cause

Multiple 5 Why Chains

Complex problems often have multiple contributing causes. Run parallel 5 Whys chains:

## Multiple Why Chains

**Problem:** Customer complaints increased 50%

### Chain A: Response Time
Why 1: Response time increased → Support queue grew
Why 2: Queue grew → Fewer agents available
Why 3: Fewer agents → High turnover
Why 4: High turnover → Poor working conditions
Why 5: Poor conditions → No ergonomic equipment
**Root Cause A:** Lack of investment in workplace ergonomics

### Chain B: First-Contact Resolution
Why 1: FCR dropped → Agents lack knowledge
Why 2: Lack knowledge → Training inadequate
Why 3: Training inadequate → Product changes not communicated
Why 4: Not communicated → No process for training updates
**Root Cause B:** Missing process for training on product changes

### Chain C: (Additional chains as needed)

5 Whys Output Format

## 5 Whys Analysis: [Problem]

**Date:** [ISO date]
**Analyst:** 5whys-analyst
**Problem:** [Statement]

### Why Chain

| Level | Question | Answer | Evidence |
|-------|----------|--------|----------|
| Why 1 | Why [problem]? | [Answer] | [Data] |
| Why 2 | Why [answer 1]? | [Answer] | [Data] |
| Why 3 | Why [answer 2]? | [Answer] | [Data] |
| Why 4 | Why [answer 3]? | [Answer] | [Data] |
| Why 5 | Why [answer 4]? | [Answer] | [Data] |

### Root Cause
[Final root cause statement]

### Validation
- [ ] Specific and actionable
- [ ] Systemic (prevents recurrence)
- [ ] Within our control
- [ ] Each step logically connected

### Corrective Action
| Action | Owner | Due | Status |
|--------|-------|-----|--------|
| [Action to address root cause] | [Name] | [Date] | Open |

5 Whys Mermaid Diagram

flowchart TD
    P[❌ Problem:<br/>Website crashed<br/>during launch]
    W1[Why 1: Server ran<br/>out of memory]
    W2[Why 2: Application<br/>had memory leak]
    W3[Why 3: New feature<br/>not load tested]
    W4[Why 4: No load testing<br/>in CI/CD pipeline]
    W5[Why 5: Load testing<br/>not prioritized initially]
    RC[🎯 Root Cause:<br/>Missing load testing<br/>in CI/CD setup]

    P --> W1
    W1 --> W2
    W2 --> W3
    W3 --> W4
    W4 --> W5
    W5 --> RC

    style P fill:#f99,stroke:#900
    style RC fill:#9f9,stroke:#090

Combined Approach

For comprehensive analysis, combine both techniques:

Fishbone to brainstorm all potential causes across categories
5 Whys to drill down on each high-likelihood cause
Validate multiple root causes found
Prioritize corrective actions

## Combined RCA: [Problem]

### Phase 1: Fishbone Brainstorming
[Identify all potential causes by category]

### Phase 2: 5 Whys Drill-Down
For each high-likelihood cause from fishbone:

#### Cause A: [From fishbone]
[5 Whys chain]
Root Cause A: [Result]

#### Cause B: [From fishbone]
[5 Whys chain]
Root Cause B: [Result]

### Phase 3: Root Cause Summary
| # | Root Cause | Source | Validated? | Priority |
|---|------------|--------|------------|----------|
| 1 | [RC-A] | Fishbone + 5 Whys | Yes | High |
| 2 | [RC-B] | Fishbone + 5 Whys | Yes | Medium |

### Phase 4: Corrective Action Plan
[CAPA based on validated root causes]

Corrective Action Planning (CAPA)

Action Types

Type	Purpose	Example
Immediate/Containment	Stop the bleeding	Disable faulty feature
Corrective	Fix the specific occurrence	Patch the bug
Preventive	Prevent recurrence	Add automated testing
Systemic	Address organizational factors	Update training program

CAPA Template

## Corrective Action Plan

**Problem:** [Reference to RCA]
**Root Causes:** [List confirmed root causes]

### Actions

| # | Action | Type | Root Cause | Owner | Due | Status |
|---|--------|------|------------|-------|-----|--------|
| 1 | [Description] | Corrective | RC-1 | [Name] | [Date] | Open |
| 2 | [Description] | Preventive | RC-1 | [Name] | [Date] | Open |
| 3 | [Description] | Systemic | RC-2 | [Name] | [Date] | Open |

### Verification
| Action | Verification Method | Criteria | Result |
|--------|---------------------|----------|--------|
| 1 | [How to verify] | [Success criteria] | Pending |

### Follow-up
- **Review Date:** [Date]
- **Responsible:** [Name]
- **Metrics to Monitor:** [KPIs]

Structured Data (YAML)

root_cause_analysis:
  version: "1.0"
  date: "2025-01-15"
  analyst: "rca-analyst"

  problem:
    statement: "Customer order delays increased 40% in Q4"
    impact: "$500K in refunds, 15% churn increase"
    discovered: "2025-01-10"
    frequency: recurring

  fishbone:
    categories:
      man:
        - cause: "Insufficient training"
          evidence: "New hires 3x error rate"
          likelihood: high
          confirmed: true
      machine:
        - cause: "Aging equipment on Line 3"
          evidence: "40% of failures from Machine 7"
          likelihood: high
          confirmed: true
      method:
        - cause: "Unclear procedures"
          evidence: "3 conflicting SOPs"
          likelihood: high
          confirmed: true
      material: []
      measurement: []
      environment:
        - cause: "Q4 demand spike"
          evidence: "Volume up 60%"
          likelihood: high
          confirmed: true

  five_whys:
    - chain_name: "Training Gap"
      problem: "High error rate in new hires"
      whys:
        - question: "Why high error rate?"
          answer: "Insufficient training"
        - question: "Why insufficient training?"
          answer: "Training program not updated"
        - question: "Why not updated?"
          answer: "No owner assigned"
        - question: "Why no owner?"
          answer: "Process not established"
      root_cause: "No process for maintaining training program"

  root_causes:
    - id: "RC-1"
      description: "No process for training program maintenance"
      source: "Fishbone + 5 Whys"
      validated: true
      contribution: 40

  capa:
    - action: "Assign training program owner"
      type: corrective
      root_cause: "RC-1"
      owner: "HR Director"
      due_date: "2025-02-01"
      status: open

When to Use RCA

Scenario	Use RCA?	Approach
Major incident	Yes	Full Fishbone + 5 Whys
Recurring defect	Yes	Focused 5 Whys
Customer complaint pattern	Yes	Combined approach
Minor one-time issue	Maybe	Quick 5 Whys
Proactive improvement	Partial	Fishbone for ideation

Integration

Upstream

Incident reports - Trigger for RCA
Quality metrics - Identify problems
stakeholder-analysis - Identify team members

Downstream

Process improvement - Implement corrective actions
Training programs - Address people-related causes
value-stream-mapping - Eliminate systemic waste

Related Skills

decision-analysis - Evaluate corrective action options
risk-analysis - Assess risk of root causes
value-stream-mapping - Process improvement
stakeholder-analysis - Identify RCA participants

Version History

v1.0.0 (2025-12-26): Initial release

root-cause-analysis

$ インストール

name: root-cause-analysis description: Problem solving using Fishbone (Ishikawa) diagrams and 5 Whys technique. Identifies root causes systematically and recommends corrective actions. allowed-tools: Read, Glob, Grep, Task, Skill

Root Cause Analysis

What is Root Cause Analysis?

Framework 1: Fishbone (Ishikawa) Diagram

What is a Fishbone Diagram?

The 6M Categories

Alternative Category Sets

Fishbone Workflow

Step 1: Define the Problem

Step 2: Assemble the Team

Step 3: Brainstorm Causes by Category

Step 4: Identify Most Likely Root Causes

Step 5: Validate Root Causes

Fishbone Output Format

Fishbone Mermaid Diagram

Framework 2: 5 Whys

What is 5 Whys?

5 Whys Workflow

Step 1: State the Problem

Step 2: Ask Why Iteratively

Step 3: Validate the Root Cause

5 Whys Best Practices

Multiple 5 Why Chains

5 Whys Output Format

5 Whys Mermaid Diagram

Combined Approach

Corrective Action Planning (CAPA)

Action Types

CAPA Template

Structured Data (YAML)

When to Use RCA

Integration

Upstream

Downstream

Related Skills

Version History

Repository

Actions

Related Skills