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Root Cause Analysis

The Tool and Why It’s Valuable

Addressing symptoms of a problem will not result in long-term stable performance. We must determine and control the root cause. The core goal of root cause analysis is discovering why something happened. Simply asking ‘why’ can search out deeper levels of causality. 5 Whys is a useful tool to characterize issues and to identify the root cause of a problem before proposing a solution.

Many problems have more than one root cause. If you believe this is the case, then a “fault tree” analysis can be used to identify many causes with the goal of isolating those few causes that are significant

How to Apply It

  1. Ask: “Why is this a cause of the original problem?”
  2. Document root cause answers on a whiteboard. If the group feels that there are multiple reasons, then represent this in a logic tree structure.
  3. Continue to ask why at least five times as a rule of thumb.
  4. Stop when the root cause is apparent or when a cause is controlled by a managerial level more than one level beyond the group’s level.
  5. Check the validity of the analysis by reverse logic. Start at the root cause and state, “Therefore”, then recite the next step above. Each step should logically flow from bottom to top.
  6. If you are unable to settle on a single “why,” then use the fault tree structure to map the potential reasons and further analysis to determine which is significant.
Pearls and Pitfalls
  • Failure to identify and address the root cause means the problem will recur.
  • The true root cause may not emerge quickly, so be diligent and use data and small tests to confirm you have isolated the true root cause. If the perceived root cause is out of your control, gain support from a senior leader to expand the analyses.

Example of the 5 Whys in Action

Example of the 5 Whys in Action

Sample Fault Tree

Sample Fault Tree

In root cause analysis, basic and contributing factors are discovered in a process similar to diagnosis of disease – with the goal always in mind of preventing the recurrence. ~ Sidney Dekker