December 5, 2018 | Mark Paradies

I Hate Bad Advice!

Is 5-Whys Just as Good as Any Other Root Cause System?

I really hate bad advice. I especially hate it when it promotes bad root cause analysis.

I saw a video the other day by a guy who was promoting the use of cause-and-effect and 5-Whys. He said that 5-Whys accomplished the same things as any other system and it was cheap (free) compared to those “expensive” root cause systems.

We all know how 5-Whys works. We’ve seen the Toyota example:

  1. Why did the robot stop?
    The circuit has overloaded, causing a fuse to blow.
  2. Why is the circuit overloaded?
    There was insufficient lubrication on the bearings, so they locked up.
  3. Why was there insufficient lubrication on the bearings?
    The oil pump on the robot is not circulating sufficient oil.
  4. Why is the pump not circulating sufficient oil?
    The pump intake is clogged with metal shavings.
  5. Why is the intake clogged with metal shavings?
    Because there is no filter on the pump.

Yes … That is 5-Whys as taught by the expert, Taiichi Ohno.

And you probably have read the comparison that I did comparing 5-Whys with TapRooT® (click HERE to read it). The comparison shows how to do a simple investigation and get much better results using TapRooT® than you get using 5-Whys.

So what does the guy giving bad advice do? He takes our answer and produces a 17-Why example to get the same results.

I guess that makes my point.

1. If somebody using 5-Whys is given the right answer, they CAN display it on a 5-Why diagram … well, maybe not with just five whys. (And asking the right 17 whys is not simple.)

2. The 5-Why techniques does not have guidance to help you reach the real causes of problems. In this case, an equipment problem (loss of lubrication) became a human factors problems when we analyzed it with TapRooT®. Before we published our results (you saw them first here), nobody was even thinking about the lack of alarms.

3. The results using 5-Whys is NOT just as good as the results from an advanced root cause analysis system (TapRooT®) even when doing a simple investigation. A TapRooT® Investigation beats 5-Whys hands down – and the effort required isn’t much more (read our book: Using the Essential TapRooT® Techniques to Investigate Low-to-Medium Risk Incidents, to see how to use TapRooT® Root Cause Analysis for a low risk incident investigation).


Because without guidance, you are just displaying the thoughts of the investigator. These thoughts can be influenced by their past experience and training and their confirmation bias (see THIS article). And confirmation bias is just one of many problems we solved in developing the best root cause analysis system – TapRooT®.

Remember, the results YOU get when analyzing the root causes of problems is what is important. The system you use should help you go BEYOND your current knowledge. 5-Whys (and cause-and-effect in general) can’t do that. Don’t take my word for it. Use TapRooT® Root Cause Analysis and compare your results to what you found in the past using 5-Whys.

Now is the time to learn to use TapRooT® Root Cause Analysis to find the real root causes of human performance and equipment failure problems. Get more information about TapRooT® Training here:

Courses & Training, Root Cause Analysis, Root Cause Analysis Tips
Show Comments

One Reply to “I Hate Bad Advice!”

  • Gary Melrose says:

    5-Whys is an excellent, cheap tool for applying pseudo-science to ‘proving’ the investigators pre-existing failure theory.

    An actual tool to record confirmation bias as you say.

    Repeat for ‘Why Tree’.

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