Root Cause Analysis: The Art of Why?

You have probably heard of root cause analysis, and perhaps even been asked to do it, but what is it? It may sound like an invasive dental procedure but, far from pulling teeth, root cause analysis is an important part of working with data.

When I first began working with data I remember being asked to perform root cause analysis and, while I had a vague idea about what it may involve, I didn't quite understand how I should go about tackling it. So, what is root cause analysis and how should you approach it?

Well, quite simply root cause analysis is a methodology used to find the underlying cause of a defect or issue. Once the cause has been identified, measures should be taken to eliminate it so that the same issue will not appear again. Whilst this can be a taxing process initially, it has the benefit of allowing any similar incidents to be solved using the same approach, making the analysis far simpler the next time around. It is also likely that team members investigating the issue will improve their knowledge and understanding of the involved data, processes, and system architecture. So how should you get started with your root cause analysis? Principally, a good approach is to ask these three questions:

• What is the problem?

• Why did it happen?

• What can be done to prevent it from happening again?

It is pretty simple really, but the “why did it happen” part can be expanded to the 5 Whys Method popularised by Toyota’s Lean philosophy. This is where the question of “why?” is asked five times to determine the underlying cause of an issue (spoiler alert: this often turns out to be due to human or process error). Often as children, we are actively discouraged from continuing to ask “why” ,as the end result is usually “because I said so!” But in the pursuit of root cause analysis, it is important to persevere to find the true answer and to not just accept the first one given as the reason for the issue (even where the first answer might be the right one, the pursuit and interrogation of the reason is also important)!

A popular story about the Jefferson Monument in Washington DC illustrates the value in following this principle. Officials were considering moving the airport as they believed that pollution was causing the rapid deterioration of the monument. Due to the huge cost of this, a team was brought in to investigate if there were other ways of saving the monument. These are the questions they asked:

• Why is the monument deteriorating so quickly?  

  • Because harsh chemicals are frequently used to clean the monument.

• Why are harsh chemicals needed?

  • To clean off the large number of bird droppings on the monument.

• 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 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 in the evening.

• Why are swarms of insects drawn to the monument in the evening?

  • Because the lighting of the monument in the evening attracts the local insects.

This story illustrates the importance of using the “5 whys” principle to establish the true cause of a problem. Rather than moving an airport, the deterioration of the monument was prevented simply and inexpensively, by turning the lights on later in the evening, with the added bonus of saving on the electricity bill!

Hopefully you now have a better understanding of what root cause analysis is and how to apply strategies to solve future problems you may encounter.