5 Whys – A root cause analysis tool for use at work and home

Search for the root cause of a situation by asking why until you find the answer.

Understanding the fundamental causes for a problem is key to permanently resolving or improving it. The 5 Whys is a method for analyzing the cause and effect relationship to identify the fundamental cause; the effect could either be an opportunity or a problem.

First, we state the effect. In this case, the effect is a problem. For example, the car won’t start. There are a few reasons this could be. Why is there no electric power? Why isn’t the battery charged? Why isn’t the alternator working? At each point, we ask why and see if that is the cause of the car not starting. By the third why, we see that the alternator belt is the problem. We might be tempted to stop here and replace the belt, but more questions could get us closer to the most basic reason, or root cause, for the problem and prevent future failures.

We need to figure out why the belt broke. We use a fourth why to determine the belt wore out – its frayed and cracked. In the fifth why, we conclude that we ignored the proper maintenance schedule.

This fifth step identifies a broken process, but is it the root cause for the problem? The asking of why should continue until a practical solution becomes evident or an economic benefit is exceeded. Why was the schedule ignored? It might be because we didn’t understand it.

There should be at least one practical solution out of the possible answers for the final why. We can use a simplified maintenance checklist, buy a maintenance-free car or use an indestructible belt. Which seems the most logical?

Projects at Fermilab use the 5 Whys process to evaluate challenges and possible risks to accomplish project goals. Risks can jeopardize the goals and completion of a project. When the root cause is identified, alternative plans are made to avoid the risks. A similar problem solving approach, Failure Mode Effects Analysis, is used to mitigate risks and to proactively plan for economical alternatives that are knowable or controllable.

Contact your Quality Assurance Representative for more information on these problem solving tools, as well as identifying and anticipating issues or risks in your processes. In the long run, these activities save time, money and frustration.

Tom King