root-cause-analysis

What this skill does

# 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."

```text
        ┌─────────────────────────────────────────────────────────┐
        │                                                         │
  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

```markdown
## 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?"

```markdown
## 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:

```markdown
## 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

```markdown
## 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

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