How to use 5 Whys Tree Diagram for Root Cause Analysis?

When there are issues such as unsatisfied customers, decreasing market share, poor quality, etc. you have to understand the root cause of the issue. Only by addressing the root cause can a problem be fixed. Root Cause Analysis (RCA) is a method of problem-solving used for identifying the root causes of faults or problems. It is widely used in a wide variety of industries.

What is A Root Cause?

All trees have a trunk, branches, and leaves. These are parts that immediately spring to mind since they are the ones we can see. The part we don’t see is the root system that anchors the tree to the ground. This root system often occupies a far larger area than the tree itself. It also continues to grow even if the tree’s branches have had a hard pruning. That’s why the system of drilling down to get to the heart of an issue is called Root Cause Analysis.

Why Root Cause Analysis?

Root cause analysis is an important step to enable companies to make the right changes to prevent faults from happening over and over again. There are three ways of dealing with recurrent problems. We can:

1. Ignore them.
2. Perform a temporary fix.
3. Get to the bottom of why they’re happening in the first place.

If we take the first option, the problem will never be solved and could escalate. If we take option two, it is the equivalent of painting over a stain or sticking a piece of tape over a leak and hoping it will hold – you’re treating the symptoms, but not the cause.

Taking the third option, i.e. analyzing the root cause, is the most time consuming, but should allow you to take steps to ensure that the problem never occurs in the future.

How to use the 5 WHY analysis?

Here are some easy steps to effectively perform a 5 WHY analysis:

1. Write down the problem. Writing helps you to formalize the problem and describe it completely. If you work with a team, it also helps the team to focus on the same problem.
2. Ask yourself why did the problem happen and write down the answer.
3. Ask yourself – looking at your answer – again why did the problem happen, and write down the answer.
4. And again, ask yourself – looking at your answer – why did the problem happen.
5. Ask yourself this question as often as necessary until the team agrees that the problem’s real root cause is identified. This may take fewer or more times than 5 WHYS.

Performing Root Cause Analysis with Multiple 5 Whys using Tree Diagram

Not like a single 5 whys analysis hand one cause at a time, the tree diagram can be used to narrow down and eliminate possible causes in a diagram, ideally to one or more addressable root causes to be considered at one single diagram.

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How to Create a 5 Whys Tree Diagram?

The Five Whys exercise is a questioning technique for going beyond symptoms of problems to identify the underlying or root causes of a problem. To facilitate the Five Whys Tree process, follow these steps:

1. Write down the problem. Writing helps you to formalize the problem and describe it completely. If you work with a team, it also helps the team to focus on the same problem.
2. Below it, list the possible causes of the problem by asking the question “Why?” or “Why is that true?” or “Why is that happening?”
3. For each of the causes, again ask the question “Why?”, and list the responses below.
4. Continue this process at least 5 times or until you have reached the source of the problem, the lowest level cause stakeholders can do something about, or the response “That is just the way it is, or that is just what happened.”

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For example: If your problem is that your car won’t start, the cause could be that it has no fuel. The root cause of this could then be that you forgot to fill up the tank, and the corrective action is, of course, to find some fuel.

Root Cause Analysis (RCA) can be decomposed into 4 steps:

1. Identify and describe clearly the problem – Write down the specific problem. Writing the issue helps you formalize the problem and describe it completely. It also helps a team focus on the same problem.
2. Identify any issues that contributed to the problem – Ask Why the problem happens and write the answer down below the problem
3. Determine root causes – If the answer you just provided doesn’t identify the root cause of the problem that you wrote down in Step 1, ask Why again and write that answer down. Repeat and until the team is in agreement that the problem’s root cause is identified. Again, this may take fewer or more times than five Whys.
4. Identify recommendations for the recurrence of problems in the future and implement the necessary solutions

RCA generally serves as input to a remediation process whereby corrective actions are taken to prevent the problem from reoccurring. The name of this process varies from one application domain to another.

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