Kevin Ian Schmidt

The 5 Why Method of Root Cause Analysis

root cause 5 why trainingKnowing how to properly conduct a 5 why root cause analysis is imperative when handling a safety incident investigation.

It isn’t just OSHA that encourages the use of root cause during an incident investigation, but also the EPA under their Risk Management Program(RMP).

Concerning Root Cause Analysis OSHA says:

During an incident investigation, an employer must determine which factors contributed to the incident, and both OSHA and the EPA encourage employers to go beyond the minimum investigation required and conduct a root cause analysis. A root cause analysis allows an employer to discover the underlying or systemic, rather than the generalized or immediate, causes of an incident. Correcting only an immediate cause may eliminate a symptom of a problem, but not the problem itself. – Source
While this is not an official order to conduct a root cause analysis, and it may not result in an OSHA fine for not complying, it can potentially result in a violation of OSHA’s General Duty Clause:

a) Each employer —

(1) shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees;
That is because the occurrence of a safety incident is a clear indication of a workplace hazard, and a failure to abate this hazard potentially means your company is no longer furnishing employees with a workplace with recognized hazards, as a full and proper root cause investigation would have uncovered the direct cause of this hazard.
So while OSHA doesn’t require it, they may cite you over not investigating properly. Anyone with an understanding of OSHA rules, regulations, and interpretations, will understand this is often the case, as OSHA will always err on the site of caution for employee protection.
Check Out: How to Improve Your Safety Culture

The 5 Why Method as a Root Cause Analysis Method for Workplace Incidents

The 5 Whys technique can also be used as a method for determining root causes of workplace incidents. What would 5 Whys look like in the context of a workplace incident investigation? Here’s the application of 5 Whys to an example mentioned in an OSHA fact sheet:

The Problem: A worker slips and falls, and suffers an injury.
1st Why: There was a puddle of oil on the plant floor.
2nd Why: Oil spilled from a compressor.
3rd Why: An oil leak from the compressor was not detected.
4th Why: The compressor was not inspected on a regular basis and repaired (if required).
5th Why and the Root Cause: The compressor was not in the maintenance system.

In theory it takes five “whys” to get to the root cause, but in practice there will be cases where you may use more or fewer than five “whys”.

This 5 Why Method Training will explain the basics of how to conduct a root cause analysis using the 5 Why method.
Adding a 5 Why Method training to your company’s incident investigation training program will improve your accident investigations to best identify hazards in the workplace along with empowering your employees in owning their safety.

Finally, according to the Washington State Department of Labor & Industries, these are the benefits of asking the 5 Whys:

  • Simplicity: Easy to use and requires no advanced mathematics or tools.
  • Effectiveness: Helps to quickly separate symptoms from causes and identify the root cause.
  • Comprehensiveness: Helps to determine relationships between various problem causes.
  • Flexibility: Works well alone and when combined with other methods.
  • Engaging: Fosters teamwork.
  • Inexpensive: A guided, team-focused exercise with no additional costs.

Combining this training with the Root Cause Worksheet as part of your total incident investigation program will allow your team to thoroughly investigate every incident.
Please check out the other components of an Incident Investigation Program, listed below:


To facilitate better root cause analysis in the workplace, I published a Root Cause Analysis workbook available on Amazon.

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5 Whys Training - Kevin Ian



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