Six Sigma: Better Root Cause Analysis and Corrective Actions
I remember first learning about root cause analysis during Six Sigma training. The main methods we used were 5 Whys and Fishbone diagrams, but somehow we had a hard time arriving at good corrective actions. It took time and testing to get there, and still the fixes were not always robust.
Since then, I have learned a lot more about RCA. Unguided deductive reasoning tools like 5 Whys or Fishbones rely heavily on the knowledge and experience of the investigator. Since nobody can be an expert in every contributing field, this leads to investigator bias. Or, as the old adage goes: “If a hammer is your only tool, all your problems will start looking like nails”.
Other issues with deductive reasoning are investigations identifying only single causes (when in reality there are several), or ignorance of generic root causes that have broader quality impacts. Results will also be inconsistent; if several teams analyze the same issue, results can be wildly divergent. Which one is correct? All of them? None?
This is where the TapRooT® methodology has benefits over other tools. It is an expert system that guides investigators to look at a range of potential causal factors, like human engineering, management systems and procedures. There are no iterations of hypotheses to prove or disprove so investigator bias is not a problem.
The process is repeatable, identifies all specific and generic causes and guides the formulation of strong corrective actions. It is centered on humans, systems and processes, and the decisions they make every day.
The supporting TapRooT® Software is designed to enable investigators to keep efforts focused and organized:
- define the problem in a SnapCharT®
- identify Causal Factors and Root Causes with the Root Cause Tree®, and
- formulate sustainable corrective actions using the Corrective Action Helper® module
The TapRooT® process avoids blame, is easy to learn and quickly improves root cause analysis outcomes.
In Six Sigma parlance, the SnapCharT® is used for problem definition (Define), the Root Cause Tree® and trending for root cause identification (Measure and Analyze), and the corrective action process to define effective fixes (Improve).