The “5 Whys” method is a product of the TPS (Toyota Production System).
Taiichi Ohno (considered to be the father of the Toyota Production System and a Lean Pioneer)
described the 5 Whys method as:
“the basis of Toyota’s scientific approach, he asserted that by simply repeating a why five times,
the nature of the problem as well as its solution becomes clearer.”
Let’s see a simple a exercise wherein 5 whys slowly but surely peels away the layers of symptoms to reach the root-cause of a problem.
Sample Problem: We are not getting adequate customer feedback, despite having a mechanism.
Why 1: Why are we not getting adequate customer feedback?
Reason: Because customers are not filling up the feedback forms properly, and simply leave the main field empty.
Why 2: Why is the feedback section field left blank?
Reason: Because they were not sure of whether or not to fill it up …
Why 3: Why were they not sure? A field is given and surely people like giving feedback (don’t they?)
Reason: They did not see it as mandatory.
Why 4: Did we place a request in the field mentioning it as mandatory
Why 5: Then why did the customers not see it.
Reason: The font underneath the field (requesting the field is mandatory) in our forms was too small for majority of our customers to read and they simply ignored it …
In the simple example above, we saw that how “5 Whys” were more than adequate to reach the root-cause of the solution, but in complex scenarios these 5 Whys are often coupled with an “Ishikawa Diagram”, which is essentially a “fishbone” diagram showing the “cause and effects” in a situation.In the complex scenarios once the major causes to a particular effect are established properly, it is only then that 5 Whys are used to further drill down these to reach the root-cause of the problem.
In any case, while we will discuss more Lean Tools in these blogs and ProSigma workshops, it is very important to remember that even asking the right questions requires an open minded approach and a persistent problem solving attitude when trying out this simple lean tool “5 Whys”.
Also remember, it is mostly anecdotal that 5 Whys are surely going to yield a root cause, therefore at times more iterations of the Whys may be needed and, with a different set/line of questioning in order to find if there are multiple root-causes in a particular problem area that may need to be addressed, in order to properly solve the problem at hand.
In complex scenarios once the major causes to a particular effect are established properly, it is only then that 5 Whys are used to further drill down these to reach the root-cause of the problem.