July 18, 2012 | Barb Carr

Root Cause Tip: Root Cause Tree Q&A

TapRooT® Instructor, Michele Lindsay, answers a great question from one of the attendees of the 2-day TapRooT® Root Cause Analysis training course held at the 2012 Global TapRooT® Summit in Las Vegas, Nevada.


Question from attendee:

I am presently using the techniques I learned to conduct my own RCA of the same incident we presented during the class and I had a question:

After grouping the conditions under each causal factor and working your way through the RCA tree on each causal factor, are you to only use the conditions grouped under that particular causal factor or are you allowed to use a condition that was grouped under a different causal factor?

My understanding is that you are to only use the conditions grouped under that specific causal factor and not reach out to other conditions from other “groups” as supporting evidence for the RCA.  I found during the class that the practice of using other conditions from other groups as supporting evidence to say either “yes” or “no” was occurring very often and that puzzled/troubled me.  In my opinion, if you were allowed to reach for other conditions not grouped under the causal factor in question, this negates the purpose of grouping conditions in the first place.  Am I wrong in my understanding of the purpose for grouping conditions?

Michele’s answer:

You are quite right that once conditions are grouped and Causal Factors identified, you really should stay within your “grouping” as you work through the RCA process.

– if the condition was put in under one Causal Factor, but applies better to the another, consider moving the condition (the “so What” test helps with this) or put it both places if it applies in both. Theoretically, if it supports a Root Cause, the condition should be associated with that Causal Factor.

– if one is wandering out of a Causal Factor and “poaching” conditions to support the current Causal Factor being analyzed, when you read the question from the dictionary that you want to answer “yes” to, then add “and that’s why … (then insert Causal Factor here). If the answer is “no,” you are wandering off, if “yes,” move the condition over, if “no,” then don’t select the Root Cause.

If a team does wander off and poach conditions from another Causal Factor, you may see duplicated Root Cause, for the same reason (answered “yes” to the same question) in 2 RCA for different Causal Factors. During your sanity check at end of the process you should catch it.

So the purist in me agrees with your conclusion, but the tool is robust enough to handle good use and weaker use.


Thanks for sending in the question and answer to share with others, Michele!

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