This month’s question

My organization uses root cause analysis (RCA) to achieve the objective of ISO 9001:2015, clause—determining the causes of the nonconformity. Our external auditor has warned us repeatedly that we don’t go deep enough to find the root cause of our defects.

We have identified several changes to make to our processes, tools and training, but we must do more to manage the risk of a major nonconformance. I would appreciate your help defining “deep enough.”

Our response

Let me start by saying you’re not alone! I’m glad your external auditor is emphasizing an effective RCA with required depth. But before we get into the depth of root cause, let’s first review the circumstances that lead to a shallow corrective action.

A natural tendency is to immediately address the situation by taking swift action, regardless of whether that action will prevent the problem from recurring. Here are a few examples of shallow analyses:

  • A customer complains about a defective manufacturing lot so you send an inspector to screen the lot.
  • A customer is dissatisfied with the organization’s service quality so you give the customer store credit or a gift card.
  • An employee falls from a ladder so you provide refresher safety training.
  • A supplier misses a delivery so you expedite the shipment by air.

While these actions are necessary to quickly appease a customer, legally protect the organization and continue day-to-day operations, they are containment actions. They don’t address the root cause of the problems, which means the problems are bound to happen again.

Most organizations that have a quality management system (QMS) implement a corrective action process and are required by the QMS to perform RCA. RCA tools range from a simple five whys analysis to design of experiments, or a scatter plot to a nonlinear regression plot.

But the issue isn’t a lack of processes, tools or even training—it’s a lack of management commitment. Problem solving requires resources from a competent cross-functional team to quickly dig deeper to find the root cause.

In a fast-paced organization, people’s attention span is limited for many reasons, such as competing priorities or putting individual career growth ahead of organizational growth. In most cases, if the root cause isn’t found in the first few days, the RCA either is abandoned or hurried along. Only management’s commitment can keep people focused.

Organizations always are juggling multiple issues, so it comes down to who in the organization has the most power and authority to sway the key resources to his or her side to get things done. Quality professionals have no control over their organizations’ power dynamics so they must strike when the iron is hot. They must capitalize on the first few days when the RCA initiative is highly visible by making the best use of key resources and getting to a resolution before those resources are diverted to a new problem.

How deep is deep enough?

The depth of RCA always has been a pressing question. How deep is deep enough? The answer is deep enough to prevent the problem from recurring. In his article “Flip the Switch,”1 Gary G. Jing provides three RCA guidelines to follow:

  1. The leverage point principle: Focus on causes with high leverage and high frequency in the span of control. These causes should be considered first as the root causes.
  2. The Pareto principle (or 80-20 rule): This principle states that, typically, most effects come from few causes. It might be harder for some people to see the link between the span of control and return on investments.
  3. The span-of-control or sphere-of-influence principle: This principle is used to identify where to stop drilling down the chain of causation and select the preferred root causes to pursue.

Span of control and sphere of influence focus on controllable factors. A snowstorm, for example, is not the root cause of missed deliveries—failing to anticipate weather conditions and not having a contingency plan are. Table 1 shows examples of noncontrollable factors and how an organization can mitigate them. Another tip is to keep digging deeper until you reach the process or system that allowed the root cause to happen.

Table 1

Sometimes, RCA consistently points to human error, and the corrective action is to retrain the operator. But human error rarely is the root cause—W. Edwards Deming proposed that the system is at fault 94% of the time.2 So if an RCA points to human error, it’s because either the investigator lacks RCA skills or lacks the patience to conduct a detailed analysis to understand the real root cause.

There are instances in which a human makes an error. They are comprehensively described in the article “Human Factors: Managing Human Failures.”3, 4 Even in these circumstances, management can provide resources, systems, controls and an environment to help prevent or reduce the frequency of human errors.

Just a theory

Unless the problem is prevented from happening again, root cause is just a theory. It’s important to create meaningful corrective actions to prevent recurrence of the problem. I have seen organizations spend weeks and months of subject matter experts’ time and efforts to get to a root cause only to not follow through with the necessary corrective actions.

It’s a drain on an organization’s resources to archive an RCA without action, so management should be committed to seeing the corrective actions through to closure. Consequently, employees may not drill deeper in a future RCA if they think management won’t follow through with implementing corrective actions and preventing recurrences.


  1. Gary G. Jing, “Flip the Switch,” Quality Progress, October 2008, pp. 50-55.
  2. W. Edwards Deming, The New Economics for Industry, Government, Education, Massachusetts Institute of Technology Press, 1994, p. 33.
  3. “Human Factors: Managing Human Failures,” Health and Safety Executive, www.hse.gov.uk/humanfactors/topics/humanfail.htm.
  4. “Human Failure Types,” Health and Safety Executive, www.hse.gov.uk/humanfactors/topics/types.pdf.


Barsalou, Matthew, “Square in the Crosshairs,” Quality Progress, January 2017, pp. 24-28.

“Human Failure Types,” Health and Safety Executive, www.hse.gov.uk/humanfactors/topics/types.pdf.

Kachoui, David, “Know your Roots,” Quality Progress, October 2015, p. 80.

Rooney, James J., and Lee N. Vanden Heuvel, “Root Cause Analysis for Beginners,” Quality Progress, July 2007, pp. 45-53.

This response was written by Govind Ramu, program manager, E2E Closed Loop Learning, Google, Mountain View, CA.

This article is right on target! More often than not I see my RCA brushed aside because it is not as important to others as it is to me as the Quality professional. That is until it happens again. I plan to share this article with some key players and try to start up much needed discussions. Thanks!
--Amanda, 07-18-2018

It is true that sometimes the system root cause may not be reached or addressed by 8D teams for several reasons listed above. For such cases, the Management should be able to understand the risks and understand the consequence of possible repeats. This article is a very good reminder on what grounds to cover for an effective RCA.
--Raymond Medina, 07-11-2018

Thanks Govind for the wonderful writeup. It highlighted several key factors when digging and deciding for root cause:
1. The commitment (or determination, typically from management) to completely address the problem.
2. The (corrective) actions (or investment) to address the identified root cause(s).

Worth noting that both involve / depend on how people calculate the return on investment (ROI). Believe or not and ironically, RCA usually never mention ROI. Yet people always make business decisions based on ROI, maybe subconsciously in many of the cases. It’s critical that in the ROI calculation to have a long-term big picture view. Then the actions (solutions) will be more likely long-term root cause oriented.
--gary jing, 07-08-2018

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