5 Whys

09/03/2014 9:336 commentsViews: 215

What is 5 Whys?

5 WhysThe 5 Whys is an iterative question-asking technique used to explore the cause-and-effect relationships underlying a particular problem. The primary goal of the technique is to determine the root cause of a defect or problem. (The “5″ in the name derives from an empirical observation on the number of iterations typically required to resolve the problem.)

Example

  • The vehicle will not start. (the problem)
  1. Why? – The battery is dead. (first why)
  2. Why? – The alternator is not functioning. (second why)
  3. Why? – The alternator belt has broken. (third why)
  4. Why? – The alternator belt was well beyond its useful service life and not replaced. (fourth why)
  5. Why? – The vehicle was not maintained according to the recommended service schedule. (fifth why, a root cause)

The questioning for this example could be taken further to a sixth, seventh, or higher level, but five iterations of asking why is generally sufficient to get to a root cause. The key is to encourage the trouble-shooter to avoid assumptions and logic traps and instead trace the chain of causality in direct increments from the effect through any layers of abstraction to a root cause that still has some connection to the original problem. Note that, in this example, the fifth why suggests a broken process or an alterable behaviour, which is indicative of reaching the root-cause level.

It is interesting to note that the last answer points to a process. This is one of the most important aspects in the 5 Why approach – the real root cause should point toward a process that is not working well or does not exist.Untrained facilitators will often observe that answers seem to point towards classical answers such as not enough time, not enough investments, or not enough manpower. These answers may be true, but they are out of our control. Therefore, instead of asking the question why?, ask why did the process fail?

A key phrase to keep in mind in any 5 Why exercise is “people do not fail, processes do”.

There are two primary techniques used to perform 5 Whys:the fishbone (or Ishikawa) diagram and a tabular format.These tools allow for analysis to be branched in order to provide multiple root causes.

 

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