November 18, 2020 | Mark Paradies

How Can You Tell If You’ve Reached a Root Cause? [Root Cause Test]


What is a Root Cause?

Root Cause Test: Before you can tell if you’ve reached a root cause, you probably should define a root cause.

Old Definition of a Root Cause:
The most basic cause (or causes)
that can reasonably be identified
hat management has control to fix
and, when fixed, will prevent
(or significantly reduce the likelihood of)
the problem’s recurrence.

The above definition was the one we created in the 1980s and used until late in 2006. But we published a new definition in our 2008 TapRooT® Book:

Modern Definition of a Root Cause
The absence of a best practice
or the failure to apply knowledge
that would have prevented the problem.

For a whole article about the definition of a root cause, see:

Definition of a Root Cause

Now you are ready to learn about root cause tests to tell if you have reached a root cause (or root causes) in your investigation.

How Can You Tell If You’ve Reached a Root Cause? [Root Cause Test]

Some root cause analysis tools don’t give you much guidance when it comes to deciding if you’ve reached a root cause (a root cause test). How far do you need to dig?

When did you dig deep enough?

For example, if you ask “Why?” five times, you have reached a root cause using the 5-Whys technique. But some people say that five is not a magic number. You may need to ask “Why?” more or less than five times. I’ve even seen a 17-Why example. So how do you know if you have reached a root cause?

I’ve seen people describe a “root cause test.”

For example, the Washington State Office of Financial Management’s test for a 5-Why root cause analysis is:

When you reach a circular answer like
“because that’s just the way it is”
then you have likely reached the root cause.

I’ve also seen people say that you need to dig until you’ve found the “underlying” cause. They usually give a couple of examples of what they think are underlying causes and you are good to go!

Some say that the underlying cause must be a “management system” cause.

Another root cause test is to dig past the symptoms until you get to the “true” causes.

Another test is to dig until the answer (fix) is obvious.

I’ve seen someone recommend the trial and error method for “testing a root cause.” You find what you think is a root cause, implement a fix, and if the problem doesn’t repeat, you found the root cause. If it does repeat, you didn’t find the root cause and you need to try again.

ASQ provided this advice on a video at their web site…

First, there are three key questions to consider:

  1. RELEVANCE – How relevant are the questions and answers to the original cause or effect that you are investigating.
  2. CONTROLABILITY – Did you find a root cause that actually helps control or avoid the situation.
  3. SIGNIFICANCE -Are the questions and answers significant enough considering the project scope.

ASQ also provides another tip. Stop asking why when the answer is a process, policy, or person. They say, often these answers turn out to be a root cause.

I Don’t Like the Guidance Above [The Root Cause Tests]

Here is the bad news. I don’t think ANY of the guidance above is very good for consistently identifying root causes.

I don’t like any of these root cause tests!

The suggestions above are based on your judgment and knowledge. Since each person’s judgment and knowledge is different, there won’t be consistency in identifying root causes.

If root cause analysis isn’t repeatable and consistent, it isn’t really finding root causes.

So, what should you do?

Advanced Root Cause Analysis

Instead of wondering if you have reached a root cause, you could use a system that guides you to root causes and tells you when you have reached a root cause. What root cause system does this?

TapRooT® Root Cause Analysis

TapRooT® Root Cause Analysis addresses all the fundamentals of root cause analysis with advanced techniques.

TapRooT® Root Cause Analysis is the only system with the TapRooT® Root Cause Tree® and Dictionary.

The top of the Root Cause Tree® Diagram is shown above. It leads you to the root causes on the back side of the tree. A sample of a root cause, Lights Need Improvement, is shown in the Human Engineering Basic Cause Category below.

All of the root causes and the process for using the TapRooT® Root Cause Analysis System are documented in the TapRooT® Books and the Root Cause Dictionary.

Root Cause Tree® Dictionary

Here’s a video of Mark Paradies discussing TapRooT® Root Cause Analysis with Kathy Ireland…

If you would like a white paper that provides an example of how TapRooT® Root Cause Analysis works to guide you to root causes, fill out the form below and submit it:

TapRooT® Root Cause Analysis Training

For more information about the training that can teach you the advanced TapRooT® Root Cause Analysis, see:

We hope to see you at a TapRooT® Root Cause Analysis Course before you have a serious incident (to prevent ever having a serious incident).

Root Cause Analysis Tips
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