RCA – Multiple Root Causes?

Hi,
After studying your case, I would like to mention the following:-
a) The case study clearly highlights about the communication gap from central team to other stake holders.
b) Production team can be right on their action since the practice till the moment was considering the lastest one as approved one.
c) In order to avoid the same in future central team should give the clear communication to all stake holders especially on approvals.
Just my opinion.
Regards
Prabhu V.

Follow DMAIC and numerically find how much each cause contributes to the problem. If they are so confident on the reason, data should be readily available.

Evaluating using FMEA works best when analysis end up with more than one cause identifies during RCA.

So your main question had to deal with how do you identify the primary and secondary root cause? Ask yourself, why is picking one to be the primary important? Why not solve both?

My experience has been that incidents are rarely the result of a singular event or failure. Often (especially when there is a singular incident), there is a “perfect storm” of several causes coming together to create an ideal environment for the failure to occur. This is one of the problems with the “5-Whys”; if you aren’t careful it leads to a very linear thought process and it takes a skilled facilitator to prevent the team from developing tunnel vision.

Another item I’ve learned is that the Six Sigma and Lean tools have their limits on the types of problems they can effectively solve. For example, if it is a repeated problem relative to a process, the tools and DMAIC method are ideal. You can control chart it, gather data and using statistics determine the effect of various X variables on your problem (the Y variable), or do some process mapping and determine where the problem points in the process are. However, if it was a one-time accident, a singular incident, there may not be the data to chart or analyze. There may be no process they were following. So the Six Sigma tools, the Lean tools, and even the DMAIC methodology may not be ideal. I know there are some (my colleagues included) who think DMAIC is highly universal and can be applied to everything – – but there are better tools for investigating singular events.

For investigating singular events, Ishikawa diagrams and the 5-Whys can be helpful. A few years ago I came across Cause Maps. ThinkReliability.com does a good job at explaining them. I’ve found this mapping technique not only effective at going deep, but also broad and mapping that “perfect storm.” You can actually see the root structure of the problem (using a plant metaphor). It makes it easy to see the contributing branches and shows you that if you don’t sever each one, the problem (the plant) could come back.

So, I would suggest not limiting yourself by classifying primary and secondary causes. If you’ve narrowed it to 2, then take them both out. If you are investigating singular events (where there isn’t clear data, a process, or a pattern of events) then check out Cause Maps.

@Shelby Jarvis From your response I can see you are an advocate of Occam’s Razor which is a principle of parsimony, economy, or succinctness used in problem-solving devised by William of Ockham (c. 1287–1347). Basically the concept of “Keep It Simple Stupid.”

That was probably a good idea in the 13th and 14th century. It is currently not the 13th or 14th century and hasn’t been for quite a while. You are essentially proposing brainstorming which is really what 5Y’s are. Turning it on and off – good idea but it really helps to understand what and why it is turning it on and off.

Doing this type of weak hearted problem solving is how companies have gotten to the point where it is one band aid on top of another. Remember Einstein’s quote “We cannot solve our problems with the same thinking we used when we created them.” So in your proposal (particularly the 5Y) where is the new knowledge coming from so that we don’t have the “same thinking” that created them.

This whole concept that there is someone walking around with the answer to every problem we face and just won’t tell anyone until someone specifically asks them is a completely inane concept. It is unbelievable what people will buy into to avoid actually have to do some work to fix a problem.

To the original post – multiple root causes in not unusual but a single root cause is. next time you run a DOE and you find a single factor that accounts for 100% of the variation let me know. The whole concept of R-square is so you can judge how much of the variation is accounted for in your model.

Just my opinion.