It doesn't matter what type of industry you're in, if failure isn't an option at your plant, you'll want to understand why these investigations sometimes fail their mission.

In the nuclear power industry, the primary mission of a root-cause investigation is to understand how and why a failure or a condition adverse to quality has occurred so that it can be prevented from recurring. This is a good practice for many reasons—and a lawful requirement mandated by 10CFR50, Appendix B, Criterion XVI.

To successfully carry out this mission, a root-cause investigation needs to be evidence-driven in accordance with a rigorous application of the bedrock of all root-cause methodologies: the Scientific Method. Consistent with the Scientific Method, underlying assumptions have to be questioned and conclusions have to be consistent with the available evidence, as well as with proven scientific facts and principles.

Sometimes root-cause investigations fail to fulfill their primary mission and the failure recurs. In that regard, diagnosing the root cause of root-cause investigation failures is, in itself, an interesting topic. Here are three common reasons why some root-cause investigations fail their mission.

Reason #1: The Tail Wagging the Dog
As a root-cause investigation proceeds and information about the failure event accumulates, some initial hypotheses can be readily falsified by the preliminary evidence and dismissed from consideration. The diminished pool of remaining hypotheses will likely have some attributes in common. More work is then usually needed to uncover additional evidence to discriminate which of the remaining hypotheses specifically apply.

At this point in the investigation, it may become apparent what the final root cause might be—especially if the remaining pool of hypotheses is small and they all share several important attributes. At the same time, it also becomes apparent what the corresponding corrective actions might be.

By anticipating which corrective actions are more palatable to the

Evidence that appears to support the root cause and lead to more palatable corrective actions is actively sought, while evidence that might falsify the favored root cause is not actively sought. Evidence that could falsify a favored root cause may be dismissed as being irrelevant or not needed. It may be tacitly assumed to not exist, to have disappeared or to be too hard or too expensive to find. It may...(Read whole article)