Five whys is a method of root cause analysis in which the researcher repeatedly asks “why?” in order to get down from high-level symptoms to the underlying root cause(s). Each answer forms the basis for the follow-up question. Initially developed by Sakichi Toyoda for Toyota Motor Corporation during the evolution of its manufacturing methodologies it was used to understand why new product features or manufacturing methods were needed. Now it is used as a part of a Kaizen, Lean, and Six Sigma. Although there is a lot of criticism of the method, it is still a very useful heuristic for management.
There is a well-known story that often goes with the method to explain how it works. It goes roughly like this:
Problem: One of the monuments in Washington D.C. is deteriorating.
Why #1 – Why is the monument deteriorating?
- Because harsh chemicals are frequently used to clean the monument.
Why #2 – Why are harsh chemicals needed?
- To clean off the large number of bird droppings on the monument.
Why #3 – Why are there a large number of bird droppings on the monument?
- Because the large population of spiders in and around the monument are a food source to the local birds
Why #4 – Why is there a large population of spiders in and around the monument?
- Because vast swarms of insects, on which the spiders feed, are drawn to the monument at dusk.
Why #5 – Why are swarms of insects drawn to the monument at dusk?
- Because the lighting of the monument in the evening attracts the local insects.
Solution: Change how the monument is illuminated in the evening to prevent the attraction of swarming insects.
The thing is this is NOT quite what happened and the missing pieces of the story actually paint a much more robust and complete picture of the nature and complexity of real-world problem-solving.
First, cleaning chemicals did not cause an issue, it was the sheer amount of water used during cleaning, seeping into cracks, and increasing structural deficiencies.
Second, although the prevalence of insects did invite a large population of spiders, which in turn brought the starlings and sparrows, it was the midges themselves that necessitated the bulk of the bathing due to them laying dark masses of eggs all over the monument.
Third, (and this is where the whole story becomes interesting), delaying the lighting at night was indeed successful in reducing the number of midges AND there was the added bonus of money saved on energy costs, BUT YET the improvement still was not implemented long-term. Yes, you read that correctly. Allow me to elaborate.
The six-week pilot program confirmed an 85% reduction in midge infestation. BUT the change in the timing of the lights drew ire from those seeking to capture breathtaking images of an illuminated memorial against the backdrop of a sunset blazing across the Potomac River. As of this January 1992 article, Park Service officials were still evaluating whether to pursue a permanent change to the timing of the lights, but by September of 1995, the countermeasure was no longer under consideration due to the overwhelming number of complaints from photo-seeking tourists.
Authorities spent another 5 years to dissuade birds, spiders, and midges from congregating on the memorials, which included the installation of wires, metal spikes, netting, and clear plastic. But without addressing the underlying root cause of the problem (the timing of the lights), these actions had little to no impact on easing the amount of cleaning required.
The moral of the story
One lesson to be learned from this story is that a thorough understanding of cause and effect has a great impact on the efficiency and effectiveness of solutions. The other lesson, however, is how difficult it is sometimes to implement a perfectly sound strategy in a real-life situation.
