RCA – Past, Present, and Future (a three-part series) Part 1

Brian Hughes, Senior VP

May 2, 2017

An attendee at a public seminar recently asked if I’d compare and contrast RCA methods.  I can appreciate this question.  I mean seriously – put yourself in the position of someone tasked with identifying an RCA method.  How do you choose?  What would be the basis of your choice?

In the interest of remaining objective, I won’t be recommending any single method over any other.  Obviously, I work for Sologic so I’m inherently biased.  But that doesn’t mean I’m not also objectively interested in the differences between current offerings, as well as their evolution over the decades.  I am interested in our history as an RCA provider in the same way that I’m interested in my own family tree.  And any objectively introspective effort focusing on our origins often leads to profound insights and implications for our future.  The point is this:  His question was based in his own self-interest in choosing the right path, just as my own willingness to answer him objectively was based in my own concerns and interests about who we (Sologic) are and where we are going.  It’s a big question... and here’s part 1 (of 3) of my attempt at an answer.

The Past (Part 1)
To understand RCA, we need a basic understanding of its modern origins.  Of course, introspection has been with humans from the beginning of cognition.  The questions “why?” and “how?” have universally propelled humans forward.  But often, answering these questions is difficult.  The main challenge is complexity – there is just so much information to process.  How to make sense of it all, particularly when survival demands it?  

 A primary strategy we developed as a species is to recognize patterns in the complexity, and to then employ a system of rules pertaining to these patterns.  Along with this, we also developed a system of specialization which allows members of a society to focus on a single thing.  I don’t grow wheat, but I eat it.  I don’t make computers, but I use them.  Not everyone teaches root cause analysis, but I do.  Specialization allows for repetition, and repetition leads to more rapid pattern recognition.

 Once we recognize consistent patterns, we develop a system of rules based on those patterns.  For instance:

Example 1:
Pattern Recognition:  Plants grow thicker where we throw manure.
Rule:  If I use fertilizer on my crops, then I’ll grow richer crops

Example 2:
Pattern Recognition:  The alignment of the stars coincides with predictable seasons.
Rule:  If I plant when the stars indicate springtime, then I’ll maximize my growing season, thereby reaping a larger harvest in the fall.  

Example 3:
Pattern Recognition:  People who possess both a natural knack for logic along with an outgoing, friendly personality often have the most success as root cause analysts.
Rule:  If our class focusses on a simple, logical process along with the basics of human interaction, we will produce a higher percentage of competent root cause analysts!

What’s the point, you may be asking?  Pattern recognition and specialization have proven to be key components for human survival and advancement.  

But how does this relate to different RCA methods?

Root cause analysis is a structured, standardized form of problem-solving.  It needs both the structure – to provide support, and the standard – to provide consistency.  Developing both the structure and the standard requires the combination of pattern recognition and rules I described above.  This provided the genesis for the two earliest, and subsequently most prolific, methods of root cause analysis:  The 5 Whys and the Fishbone (Ishikawa) Diagram.

The 5-Whys:
The 5-Whys method is about as simple as its name suggests:  Ask why five times, and you’ll likely arrive at the root cause.  

Wait, can it really be just that simple?  Actually, no – not really.  But it’s a good start.  The 5-Whys is based on the simple rule of conditional logic that follows the pattern “If..., Then...”

For instance, if I knock over my cup of tea, then the tea will spill.  And its opposite is also true:  If I don’t knock over my cup of tea, it will not spill.

5-whys cause and effect

But the 5-Whys takes it further than that, identifying precedents to each cause.  The number “five” is random, but hey – they had to balance it out somewhere.  By looking at preceding causes, the 5-Whys introduces time into the model.  The underlying premise is if you go backward in time to uncover preceding causes, you will eventually find the “root cause.”  A second rule is then deployed:  If you control the “root cause,” then you solve the problem.  Notice that I put “root cause” in parentheses.  We’ll get to that in Part 2.

5-whys cause and effect detailsBenefits of 5-Whys:

  1. The 5-Whys is easy:  Anyone can use it.
  2. The 5-Whys is quick:  How long can it take to ask and answer the same question five times?
  3. The 5-Whys is helpful:  By examining precursors, the 5-Whys improves understanding and the process of identifying a solution.

Fishbone (Ishikawa) Diagram:
The Fishbone leverages a different rule of logic based in different patterns:  The logic of syllogism.  This logic works by drawing conclusions about different things based on shared traits and characteristics.  The following expression by Aristotle may be one of the most famous logical statements of all time:

“All men are mortal.
Socrates is a man.
Therefore, Socrates is mortal.”

We don’t need to test the theory for everyone – we can assume that humans are universally mortal.  Killing Socrates should be enough!

Applied to answering the questions of why and how events occur, the Fishbone method defines standard high-level categories.  The classic four are:

  • Manpower
  • Methods
  • Materials
  • Machinery

Ishikawa recognized that the industrial problems he was involved with at the Kawasaki shipyards would typically involve causes from these categories.  The classic Fishbone method works by brainstorming causes associates with each category, which results in sets of causes all sharing at least one similar trait which permits membership in the group.  Are these categories set in stone?  No – they can be changed and/or additional categories can be included.  But the underlying logic – that things with at least one shared trait can be grouped together – is always consistent.

Fishbone Ishikawa RCA

You may notice however that the Fishbone diagram, unlike the 5-Whys diagram, does not account for time.  The presence of time is implied – it’s not explicit in the diagram.  Therefore, in order to arrive at a “root cause,” the Fishbone process calls for investigation participants to vote on what they think the root cause is.  Once determined, solutions can be adopted.
Benefits of Fishbone:
The primary benefit to the Fishbone is it helps the investigator identify causes from diverse sources.


Conclusion of Part 1:
Of course, we constantly improve the tools and processes we use.  That is certainly true for the 5 Whys and the Fishbone.  Most of the current crop of root cause analysis providers involve some form of improvement to these methods.  In Part 2, we will examine the primary deficiencies with the 5 Whys and Fishbone, and explain in general sense what has been done to improve them.