When should I use the “5-Whys” causal analysis?

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Causal Analysis has many tools for getting to the “root” cause of a problem. This subject has many ways to attack it with the “5-Whys” being a generically accepted rudimentary process of quickly rooting out the originating driver(s) for an issue. There can be issues with multiple degrees of significance or “levels” of how deep an investigation must go to find personal and organizational issues, sometimes referred to as Basic Low Level (BLLs), Apparent Cause Evaluations (ACEs), or even higher order, “Root Causes.” Note the capital “R.” A Root Cause is extremely significant, formal, and should require a lot of teamwork: multiple investigators, multiple reviewers, and multiple techniques to discover what happened, causal factors, and then to develop what some people call “Corrective Actions to Prevent Recurrence” (CAPRs – pronounced as “capers“). In my view (some in the field are not always aligned on this) CAPRs should be created to prevent this same type event, or other potential similar events from occurring in the future…. These are the highest order of corrective actions. In a similar, but a little different way, corrective actions for ACEs should prevent the same type of event from happening again, and lowest level investigations are designed for ensuring that problem is fixed in a timely fashion and that it is coded properly for trending. Root Causes and Apparent Causes have corrective actions that are typically reviewed and agreed upon by a committee based on their organizational cost and resource impact.

Note that different Corrective Action programs call the different levels of investigation different terms, but most widely accepted are the most serious “Root Cause” and the next level “Apparent Cause.” Levels are given, so you do not put all of your resources (time, money, and personnel) equally on every event.


The 5 why’s (also seen as “5Ys”) typically refers to the practice of asking, five times, why the failure has occurred in order to get to the root cause of the problem. This process is not to be mistaken as a formalized way of discovering difficult issues surrounding an event investigation.

To give this concept more context, let’s liken this process to a simplified training needs analysis (TNA). The training question could be: Does James need training to do process#1? Well, if I hold a gun to his head, can he perform the function (Is it just a case of stubborn will)? If he can perform the basic function, maybe he just needs a procedure, or some practice, but not a training class… and so on… simple, basic, and high-level… that’s what the 5-Why’s is – simple, basic, and high level – it could truly reveal something you were not aware of before, but note that it is the least powerful causal analysis technique in the Root Cause Toolbox: Event and Causal Factor Charting, Barrier Analysis, Fishbone, Timeline, Change Analysis, Substitution Analysis… and the list goes on and gets more in depth. I relate the TNA “gun to head” philosophy in the same way I do the 5Ys – it is a short and simple way to get you in the ballpark for discovering unknowns.

Of course, there can be more than one cause to a problem as well. In an organizational context, most Root Cause analysis is carried out by a team of persons related to the problem with a qualified investigator.

Where are the links?

I did not include links to websites or scholarly articles on this subject – I prefer not to think of it as a professional causal methodology for experts to use, but one that is accessible to anyone looking at an investigation. Check out the videos and see how it is used, and for a good laugh related to this material, click the picture above.


Toyota’s “Go and See” process with fishbone diagram

The 5 Whys

Gemba Glossary: The 5 Why

5 Whys

The 5 Whys Problem-solving Method


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