Root cause analysis with five times why

Central to Lean and Six Sigma is analyzing and measuring the current state before you start on solutions. There are a lot of tools available for this analyze phase of kaizen, PDCA or DMAIC. Tools like the Ishikawa diagram, Kepner-Tregoe and five times why. These tools are not mutually exclusive. You can use five times why in the Ishikawa diagram and in Kepner-Tregoe. Today we will look at five times why. 
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The basic idea behind five times why is that you can always find the root cause of any problem by just asking why five times. When people first get started on five times why they tend to fire off five quick why's. This can be fun at first, but will get boring soon and will unfortunately not help you to get at root causes.

"By asking and answering ‘why’ five times, we can get to the real cause of the problem, which is often hidden behind more obvious symptoms." — Eric Ries, The Lean Startup

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So here are some tips to give your five times why the attention and results it deserves:

  • Listen actively for the answer both verbally and non-verbally.  Do not make it a third degree cross examination in rapid fire Why's.
  • Five times why is a rule of thumb. It may be that you are at the root cause after two why's, while sometimes it may take seven why's. When the next answer starts to become repetitive or vague and someone does not seem to know what to say you need to figure out together whether you have met the threshold of your knowledge or whether you are at the root cause. 
  • Adjust your next why question to the answer given (Why was it late?, Why is this a bad thing? Etc.). This will keep both you and the other person engaged and sharp. 
  • Check whether the answers are facts or opinions. If the facts are not available yet make a note about getting at the facts in order to check your root causes. 
  • Make a visual representation of the answers. This helps in seeing the interdependences and will elicit new questions and answers. This can be a mind map, Ishikawa diagram, Kepner-Tregoe or causality diagram. 
  • Make sure your why questions are open questions to avoid getting trapped in symptoms instead of root causes. 

When you start asking questions the first answers will tend to be very obvious, but not really specific to the situation or very focused on something incidental. By asking five times why you will get at different root causes for most of the causes first mentioned like in the image below.

Five times why

This way you can go from non-specific ("I can't send information on time") to something that you can measure and check ("Schedule keeps changing"). As you can see in the image above not all root causes have been found yet, more why questions need to be asked. When analyzing root causes you may find you need to go back and measure some more data to check your root causes and earlier assumptions. This is perfectly normal. Once you have all your root causes you can check them with the team (if they have not all been working on it with you) and go to the solution phase.  

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