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Quick Guide: Root Cause Analysis

1- Introduction

Root Cause Analysis is the most important process in any problem-solving methodology, once the organization has a good understanding of the problem then appropriate solutions can be identified and implemented.

2- Methodology

This Quick Process Guide follows the methodology set by the requirements in the ISO 9001:2015 standard; in particular, those stated in section 10.2 Nonconformity and Corrective Actions, item b.

The process is based on the principle of causality (cause and effect), models the explain the transformation of matter, energy or information and finally, the verification of the hypothesis by means of empirical data.

3- Process

The process starts with the undesired event, then the Non Conformance Management process is applied to document and control the associated losses. This process is described in a separate document. The scope of causal analysis starts with the definition of the problem in terms of the impact to the business goals.

3.1- Problem Definition

Define the problem in terms of the business losses or risk, whatever is higher. For instance: $2,000 in field clean-up and repair of leaking pipe joint (not just leaking pipe). The organization should consider deviations from business goals in terms of Safety, Environment, Health and Quality that may have an impact in the internal efficiency or stakeholder satisfaction.

3.2- Identify Possible Causes

3.2.1- Cause and Effect relationship

The framework of the causal analysis is based on the cause-effect relationship. All effects have one or more causes (e.g. fire is caused by heat, combustible and oxygen) in turn one treat each of the causes as effects and then identify their causes (e.g. what was the heat source?). The transformation of matter, energy or information that takes place in the cause-effect phenomena should be supported by a plausible model or mechanism.

3.2.2- Physical, Human and Systemic causes

The physical cause should have been determined at the moment of documenting the event by direct observation of the reporter (e.g. leaking pipe causes environmental loss). Now the Physical cause is treated at the event and all the possible causes for that event are then determined.

An intermediate target is to determine the human cause. Think in terms of the actions or decisions that lead to the physical causes associated with the business loss (e.g. inadequate assembly, did not engage enough threads). Do NOT stop at the human causes, otherwise your causal analysis programs turn into a blame-assigning process.

The branches of the cause tree should end with system causes. System causes are those elements of the management system that enable the conditions for the human factors to occur (e.g. lack of standard work information).

3.2.3- Validation or Rejections of possible causes

Direct or circumstantial evidence is then used to validate or reject possible causes once the team has a good understanding of the potential causes (e.g. only three complete threads engaged and tight coupling achieved with at least six, interview of personal and could not find documented information)

The outcome of this activity can be any combination of understanding of what happened (validation) identifying what did not happen (rejection) or identifying the unknowns.

At this point the organization would have a good understanding of the causes of the event and can use their understanding of the internal capabilities and the business strategy to identify areas of focus to identify and implement solutions.

The organization may decide to start monitoring certain unknowns to evaluate the potential causal relationship in future events.

4- Supplemental Processes

The following process may be used to supplement the Causal Analysis process.

  • Non Conformance Management: This process feeds the causal analysis and focuses on the documentation, control and correction of non conforming products or services.

  • Solutions: This process follows the causal analysis. Once the causes of the problems are understood, management can use their knowledge of the business and capabilities of the organization to apply resources to reduce risk of recurrence.

  • Corrective Actions (CA): The CA process enables the reduction of the risk of recurrence of NCs in scope. Normally not all NC trigger Corrective Actions. The focus of this process should be the implementation and the verification of effectiveness of the solutions.


I am developing a series of "quick guides" to assist with the definition of quality management processes. The quick guides are brief yet complete documents that include textual and graphical (flow chart) description of the processes. Send me an email at if you want a copy of the document.

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