# Root Cause Analysis

**URL:** https://kaizumi.com/dictionary/root-cause-analysis

**Description:** Root cause analysis is a systematic process for identifying the fundamental reasons why problems occur, enabling permanent corrective action.

**Category:** six-sigma

**Tags:** problem-solving, foundational

## Definition

Root cause analysis (RCA) is a systematic approach to identifying the fundamental reasons why problems occur, rather than just addressing surface symptoms. By drilling down through layers of causation, RCA reveals the underlying issues that, if corrected, prevent recurrence. Common RCA tools include the 5 Whys technique, fishbone (Ishikawa) diagrams, fault tree analysis, and Pareto analysis. Effective RCA distinguishes between symptoms, contributing factors, and true root causes that drive permanent corrective action.

## Examples

### Manufacturing

> Defective welds appeared on an assembly line. Symptom: poor weld quality. First investigation blamed operator error. RCA using 5 Whys revealed: weld parameters incorrect → settings drift during shift → no visual indicator of parameter state → machine has no lock → original design omitted lock. Root cause: design specification gap. Solution: retrofit parameter lock and update design standard.

### Healthcare

> Wrong-site surgeries occurred despite timeouts. Symptom: marking errors. RCA revealed: surgeons marking after gowning → marking pen in sterile field → pen shared between cases → sometimes wrong site marked on prior patient's residual marking. Root cause: no standard for mark removal. Solution: mandatory mark removal protocol before new marking.

### Administrative

> Customer complaints about billing errors persisted despite retraining. RCA uncovered: errors occurred on accounts with specific plan types → training didn't cover these exceptions → exception rules weren't documented → product launch skipped documentation step. Root cause: launch checklist gap. Solution: mandatory documentation gate for new products.

## Key Points

- Root causes are factors that, if corrected, prevent recurrence
- Multiple tools exist: 5 Whys, fishbone diagrams, fault trees, Pareto analysis
- Must distinguish symptoms, contributing factors, and true root causes
- Human error is rarely a root cause—dig deeper to find system failures

## Common Misconceptions

**Root cause is always a single factor.** Complex problems often have multiple root causes, sometimes interacting. Good RCA identifies all significant contributing factors, even if one dominates.

**Asking "why" five times always works.** The 5 Whys is a starting point, not a formula. Some problems need more depth; others reveal root causes in two or three levels. The key is reaching actionable system causes, not counting questions.

## Try It

Map your own problem right here. Lay out causes across the six M's, then drill down with 5-Whys to separate symptoms from true root causes. (Also available as a [standalone tool](/tools/fishbone).)

<!--TOOL:fishbone-->

## Related Tool

Once the map points at one candidate cause, work it down a single chain with the [5 Whys builder](/tools/5-whys) — it reads each rung back to you and flags the ones that stop at a person, a fix in disguise, or something too abstract to go and see.

Pinpoint which work elements overburden an operation by charting each step's time against takt time with the [operator balance chart builder](/tools/yamazumi).

Source: https://kaizumi.com/dictionary/root-cause-analysis
Licence: free to quote and cite with attribution to Kaizumi.