Root Cause Analysis

root cause analysis
root cause analysis

Root cause photo by Tatters

Root cause analysis is a collection of tools and processes we can use to determine the most important causes for an issue we are trying to resolve. This is an important function as one of the top 5 reasons for project failures is poor root causation / no root cause identified. If we can identify the root cause to an issue, we have a good chance of solving it.

“Take away the cause, and the effect ceases.” – Miguel De Cervantes in Don Quixote.

Types of Root Cause Analysis Tools:

Getting Started with Root Cause Analysis

Before diving in with the aforementioned tools, it’s good to start with Causal Theory. In other words, Why does a certain problem exists?

To do this we start with a basic equation; Y = f(x) ;

Y is the Output of a process.
X are the Process elements that influence Y

Another way to state this is

Y is the crime ; X’s are the suspects that explain the crime of Y

Data door & Process door

Some of my instructors refer to the data door and the process door. Both can be used to get to root causation but certain tools are better in certain circumstances.

Effectiveness project – use data door.
Efficiency project – use process door.


To validate root causes identified in the Open-Narrow-Close efforts, the team should employ three tools/techniques:

Open phase

In the open phase you want to gather as many ideas as possible. To do that you might use a cause and effect diagram.

Generate as many suspects (people of interest) , Brainstorming (Cause and Effect Diagram, Fish Bone Diagram)

Narrow Phase

Narrow (SME of the team) – eliminate duplicates, narrow thru multi voting to get to a narrower list

– 5 Ys to break biggers Xs to smaller managable X’s

Close Phase

Close – validate using Hypothesis and convict them or set them free

Validated X’s will be worked on to IMPROVE

Root Cause Video

Good video, awful sound. I muted it and just clicked through at a good pace. It gets the point across.

Other Notes

Also see Linear Regression for Y = f(x)

Also see Causal Theory=f(x)

Also see Hypothesis Testing

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