Effective corrective action always involves identification and elimination of the root cause of the problem. This is often easier said than done due to not properly getting to the true root cause. If we don’t eliminate it, the problem will reoccur, guaranteed!
The simplest and effective method I have used to drive to true root cause is the 5 WHY method. Developed originally in the problem-solving total quality world of Japan manufacturing, 5 WHY has been an important tool in the improvement toolbox.
The five whys method is a way of drilling down to the root of a problem by stating the problem and asking, “Why did the problem occur?” This first “Why” is followed by asking, “Why did the answer to the first question occur?” This continues until either the root is discovered or the final “Why?” question is asked.
Here is an example that has been frequently used to illustrate the 5 WHY method to identify the root cause. It has been published in the journals of the American Society for Quality, among other places.
The Jefferson Memorial in Washington DC is a beautiful and highly recognizable marble structure located on the bank of the Potomac River. The caretakers at the memorial have battled a problem requiring them to conduct daily clean up of bird droppings which were creating an unsightly mess under the building dome and covering the floor and statue of President Jefferson. Let’s use the 5 WHY technique to uncover the root cause.
PROBLEM STATEMENT – There are bird droppings all over the memorial structure under the dome? This requires daily clean up.
WHY 1 – Why are there bird droppings all over the memorial?
Answer – Because birds congregate there each night.
WHY 2 – Why do birds congregate under the dome each night?
Answer – Birds are feeding on spiders that live under the dome.
WHY 3 – Why are spiders living under the dome?
Answer – Spiders are building webs there to trap moths and other flying insects.
WHY 4 – Why are there moths and flying insects under the memorial dome?
Answer – The insects are attracted by the lights under the dome that are on from dusk till dawn.
WHY 5 – Why are there lights on under the dome each night?
Answer – Because the National Park Service set the light timers that way. There was actually no specific reason for the timing.
The bird problem was dramatically reduced by setting the under-dome lighting to turn off after midnight which eliminated the insect and spider problem that had been occurring. Root cause was effectively identified and eliminated.
There is no magic with the number 5, only that most problem statement root causes can be found in 5 or fewer WHY’s. But there are occasions that it will take you 6 or more WHY’s to drill down to root cause. Be sure to always start with a fully vetted and agreed upon Problem Statement to address. This keeps the exercise on track to get to the best conclusion.
Peter Sheren is a quality and manufacturing professional with over 30 years of experience in a variety of industries and technologies, operating as an integral member of management teams to develop organizational quality, lean production, and technical operations functions. Peter has also gained extensive knowledge and insight into the power of using the vaunted Toyota Production System to create a lean management system that is focused on waste elimination through empowering the entire workforce. He also has expertise in implementing ISO9000 Quality Management Systems in numerous companies including multi-plant operations.
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