5 WHY Series – Part 1
An Introduction to 5-why
Learn how to find root causes of a problem by using 5-why analysis, so you can fix the
issues where it matters most. First in a series of 4 articles explaining this powerful tool.
By Karn G. Bulsuk
The 5-why analysis, used throughout the kaizen concept and in quality control, is a tool to
discover the root causes of a problem.
More often than not, people fix a problem by dealing with issues that are immediately apparent.
While it may provide a quick fix, the problem tends to rear its ugly head in the same form, or
with a different face later on. Fixing the problem by nipping it in the bud is what all leaders and
associates should aim to do.
For example, suppose we had a tree which whose leafs were all wilting and it seemed to be
dying. We could make it look better in the short run by cutting the wilted leaves, but other leafs
will continue to wilt and the tree will still by dying.
Instead, we need to investigate the cause of the wilting. Did we water the tree recently? Are there
tell-tale signs of fungi, bacteria or perhaps termites? Once we know the true issue, then we can
Another analogy would be like carpet bombing. We can try to carpet bomb and try every
solution without thinking and hope it solves the problem, which would waste time and effort.
Instead, with a bit of 5-why analysis, we are able to engage in precision targeting and fix it in
one go. The point is especially important when you deal with sensitive issues which need to be
rectified quickly and quietly.
The concept of 5-why is simple:
1. Identify the problem.
2. Ask yourself: why did this happen? Come up with all the causes you can think of.
3. For each of the causes you just identified, ask “why did this happen?” again.
4. Repeat until you’ve done steps 2 and 3 for five times. You should have identified the root
cause by this stage.
5. Find solutions and countermeasures to fix the root cause.
For example, imagine that you just finished organizing a Gala Dinner, and you had a problem in
which the catering service delivered the food 2 hours behind schedule. To find the root causes,
we would do the following:
The caterer delivered food 2 hours late.
Why did this happen?
Why was the purchase order
Because we did not prepare the purchase order on time. not prepared on time?
Why didn’t get the signatures
Because we did not get all approval signatures on time. on time?
Because we prepared the PO 3 days before the event.
Why did we prepare it late?
Because we forgot to prepare a Purchase Order.
Why did we forget about it?
Because we didn’t have a checklist to clearly
identify the tasks we needed to complete at what
In this case, the root cause is that we lacked a checklist to ensure everything was prepared at the
designated time. The solution is to prepare it.
Will there always be only one root cause?
The example above provides a simplified solution model. When performing 5-why analysis,
multiple causes will emerge from each causation branch. As a result, there will likely be several
root causes identified and they must be prioritized, so you solve the most severe and pressing
In the next articles on 5-why, several analysis models will be introduced.
Why FIVE why?
In the Toyota method, asking why five times is believed to lead to the conclusion. In reality, the
number of times you ask why will depend on the depth of the problem. Sometimes three or four
“why’s” is sufficient to reach the root cause. With a more complex problem, we can go up to
seven or eight “why’s”.
Of course, if there are too few “why’s” then it would indicate that the problem hasn’t been
analysed in enough depth and detail. Too many “why’s” could alternatively indicate over-
analysis, and that you’ve lost sight of the big picture.
Who should perform 5-why?
5-whys must only be done by those who have done a specific job or project, as they have
firsthand knowledge and experience to do so.
For example, imagine that a bank teller just mistakenly transferred money into the wrong
account. Luckily, the problem was reversed before any damage was done.
To find out the root causes of the problem, only the teller is qualified to perform the analysis
because she was the one who experienced it and knew the seen and unseen parts of the problem.
Anyone else can only speculate on why it happened, but the truth can be told only by those who
Weaknesses of 5-why
5-why is based on personal opinion on what the causes are, and two people performing 5-why
analysis on the same problem can come up with widely differing causes and completely different
The issue is slightly negated as long as the person involved in the problem performs the analysis.
If they do, then they should have enough expertise to perform an accurate analysis.
1. Identify the problem, then ask “why did this happen” to find causes. Ask “why did this
happen” to the causes, and repeat until we’ve done it five times.
2. Finding root causes allows us to solve the true problem.
3. There are usually more than one root cause.
4. Too few “why’s” may indicate insufficient analysis.
5. Too many “why’s” beyond five-why may indicate over-analysis.
6. Only the person who experienced the problem can do 5-why analysis.
7. 5-why is based on personal opinion and can be flawed, so check your logic.