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The 5G Methodology – Practical Guide for Root-Cause Problem SolvingThe
5G Methodology is a Japanese-origin lean diagnostic approach that focuses on direct observation and factual understanding. It's widely used in production engineering, quality control, and lean manufacturing to ensure decisions are made based on truth from the field.
1. Gemba (現場) – The Actual Place"Go to the source."- Gemba means the real place where the work happens – the factory floor, site, or customer location.
- Do not solve problems from a desk — observe the reality firsthand.
- Example: If a cable insulation issue is reported, inspect the extrusion line in person.
Checklist:
- Did you go to the site of the problem?
- Did you observe the operation personally?
2. Gembutsu (現物) – The Actual Thing"Examine the actual materials, machines, or objects involved."- Look at the defective parts, failed tools, or inconsistent materials.
- Never rely only on paperwork or reports.
- Example: Physically inspect the scorched cable sample, not just the complaint form.
Checklist:
- Did you inspect the actual defective product?
- Were tools or parts involved examined in person?
3. Genjitsu (現実) – The Actual Facts"Understand the actual data and conditions."- Record process values, measurements, and operator input as they happened.
- Avoid assumptions — focus on what the data truly shows.
- Example: Validate sensor readings and material feed rates using control logs.
Checklist:
- Do you have the actual process data?
- Have you verified the reports with raw logs?
4. Genri (原理) – The Fundamental Principles"Base your analysis on sound engineering or scientific principles."- Use physics, process engineering, electrical theory, etc., to explain the failure.
- Avoid subjective logic — rely on industry best practices and formulas.
- Example: Understand that poor conductor annealing leads to resistance variation using Ohm's Law.
Checklist:
- Is your root cause analysis grounded in known principles?
- Are formulas or physical laws referenced correctly?
5. Gensoku (原則) – The Standard Rules"Compare actions to established procedures and standards."- Was the standard operating procedure (SOP) followed?
- Did the team comply with ISO, UL, or internal work instructions?
- Example: Operator skipped insulation tension calibration step listed in SOP #312.
Checklist:
- Was the standard or rule followed?
- If not, why was it bypassed or misunderstood?
Summary Table – The 5Gs| Gemba | Go to the actual place |
| Gembutsu | Inspect the actual thing |
| Genjitsu | Use actual data and facts |
| Genri | Apply science and engineering principles |
| Gensoku | Check compliance to standards |
When you apply all 5Gs systematically, your root cause analysis becomes bulletproof. It builds a culture of truth, precision, and continuous improvement.