The PRESENT Value of the WHY Tree

I've written about WHY Trees twice in the recent past, first to describe their origins and secondly to describe a gross problem in the way they are being used. I'd like to end, at least for the time being, by sharing my thoughts about the present value of WHY Trees.

Actually, these BLOG posts about the WHY Tree are in response to growing criticism that I have gone too far in my dismissal of their value. Some people (mainly, the engineers in charge of corporate investigative efforts) are so annoyed at my position that they are reaching out to other methods that focus on the construction logic-type diagrams. It seems as if some people would rather construct WHY Trees than go through the life-changing DISCOVERY process that is only possible when one sits down and immerses oneself in evidence.

Have you ever seen a CSI show where the investigators constructed WHY Trees? Nevertheless, perhaps I have gone too far in my downplaying of the WHY Tree -- thus the purpose of these posts. Allow me to emphatically state the following:

Yes, I do think the WHY Tree has value (read my other posts and you'll see that I LOVE WHY Trees).

First, the WHY Tree is an excellent way to graphically communicate your conclusions so that others can quickly understand, as long as they follow the "15-year-old-rule." (They must be constructed so that any average person can understand, without any interpretation).

Secondly, the WHY Tree is an excellent way for an investigator to be assured that cause and effect relationships have been established. It is very possible to investigate an incident and think that your logic is correct, only to see that the "dots do not connect" after all. This error can be minimized by constructing WHY Trees.

But please note when the WHY Trees in the above scenarios are are constructed. They are constructed after the investigator already knows why the incident occurred. WHY Trees are not an answer-generating machine. The only answers you will ever get (even in life) will come from the evidence that life presents to you.

Are WHY Trees of any use during an investigation? Sure!

There are two scenarios where WHY Trees can be used to help an investigator pursue the right paths, before the causes are known. But these two scenarios are wrought with dangers because of the biases that can emerge when you allow yourself to drift away from evidence.

First, when investigating a technically-complex sporadic failure (low frequency, high impact) with large amounts of evidence, it is sometimes useful to use the WHY Tree to show the varying possibilities of what might have contributed to the incident. Note the word "might." If you are not sure which of several possibilities might have contributed to an incident, a WHY Tree can be used to show all the possibilities.

For example, if a fire occurred near a pump and evidence suggests 3 possible ignition sources, the WHY Tree could list these causes on the row underneath "ignition source existed."

WHY Trees are also great when working with chronic failures (high frequency, low impact), because chronic failures have multiple failure modes -- each of them "true" a given percentage of time.

For example, let's say you have a pump that fails once per day (I am being extreme to make my point). If you did an LCA on each particular incident (one each day), you'd find that the pump failed (for example) due to excessive vibration 25% of the time, leaks 55% of the time, and shaft failures 20% of the time. As you pursue the top block of the WHY Tree, row after row, each row can be handed the same way (with percentages attached to them). If the pump failure has a monetary value associated with it, the percentages end-up indicating the "value" of addressing each block of the WHY Tree. I love using WHY Tree when working with chronic failures.

WHY Trees can be very useful, if not abused.

Remember, first gather evidence. Write a paragraph explaining what you know about the Physical Causes. Then define the Human Causes, bullet-style. Finally, define the Organizational and Personal Latent Causes. I strongly suggest defining the causes, in writing, before you ever think about drawing a WHY Tree. If you start drawing your WHY Tree before you understand the causes, you'll end up spending a whole lot of time drawing trees as opposed to immersing yourself in evidence.

Remember, we're trying to change people -- because when people change, everything else will change.