8 Biggest Mistakes in Conducting Deviation Nonconformance Investigations-Part II

3. Not getting to root cause or most probable root cause

The percentage of investigations resulting in a root cause is a good metric for the health of the quality system. There are many reasons why root causes are not found. Not committing adequate time and resources is one. All too common, however, is putting in sufficient effort, having all the necessary facts and information, but still not being able to identify a root cause. This is sometimes due to the skill of the investigator involved, who may have been trained insufficiently, or does not have the technical command of the issues involved.

However, it is also surprisingly common for an investigation to conclude that “a definitive” root cause could not be identified, when all the information needed is available. A misguided interpretation of the facts, or using an unrealistic standard of “definitive” can prevent the investigation from arriving at a most probable root cause. There is no regulatory standard that requires all conclusions be “definitive.” A most probable root cause based on and justified by a thorough investigation, and review of available data and information is sufficient.

The proper root cause tool should be chosen for the problem at hand. For more difficult investigations, a Kepner-Tregoe or IS-IS NOT analysis can often tease out a challenging most probable root cause from an array of discordant facts. Using advanced root cause tools effectively takes experience and training.

There are many cases of organizations unable to realize and correct a root cause for a problem that was readily solvable and they suffered millions of dollars in losses or worse as a result.

4. Not getting to true root cause

A true root cause is the underlying reason that allowed the event to occur. Understanding the true root cause requires the collection of all relevant facts. Sometimes these are clearly understood moments after the event. Other times, it requires in-depth technical assessments and work that spans several months.

One good test for assessing if true root cause has been found is to see if the root cause needs to be stated in terms that are directly actionable, meaning it links clearly to a corrective action and is in the organization’s control. One of the simplest and most effective tests for assessing if true, actionable root cause has been found is use of the 5-Whys tool at the conclusion of an investigation, including application to outputs of a Fishbone or Kepner-Tregoe analysis.

Failure of the back-up power supply is not a true, actionable root cause. Why did the back-up power supply fail? Hurricane Mathew cannot be an actionable root cause, but an inadequate procedure for preventative maintenance of the back-up power supply is. The corrective action is to fix the procedure.