Quick Guide: Root Cause Analysis (Updated 2025)

Introduction

Root Cause Analysis (RCA) is at the heart of any effective problem-solving process. Once an organization clearly understands a problem, it can identify and implement solutions that address the true drivers, not just the symptoms.

Done well, RCA not only reduce the risk of recurrence but also improves safety, quality, efficiency, and stakeholder confidence.

This guide supports conformance to the corrective action requirements in ISO 9001:2015 clause 10.2 Nonconformity and corrective action and API Q1 clause 6.4.2 Corrective Action.

Methodology

The process is simple and well-structured to provide effective results with efficient use of resources. It is based on four pillars:

1. Causality: Every effect has one or more causes.

2. Mechanism: The cause-effect link must be explained through a credible hypothesis of transformation of matter, energy, or information.

3. Evidence: Hypotheses must be validated or rejected through objective data.

4. Risk-Based approach: Focus on solutions that balance impact, organization competencies and strategic goals.

Process Steps

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.

1. Define the Problem

   State the problem in terms of impact on the business, not just technical terms. Example: “$2,000 in field cleanup and repair due to leaking pipe joint” instead of “Leaking pipe.”

   Consider deviations from business goals in Safety, Environment, Health, and Quality. If when investigating an accident like the Titanic the team only treated the asset loss, the organization may not have mitigated the risk of loss of life if the boat sinks for a different reason.

2. Identify Possible Causes

   1. Cause-Effect Relationships

      Every effect has one or more causes and the cause-effect relationship can be followed way deep to the management system.

      • Map the chain: start from the undesired effect and ask “What caused this?” for each node.

      • For each identified cause, ask again until reaching the causes at the management system level.

      • Support each link with a plausible mechanism (e.g., biological, physical, and behavioral).

      • Light investigations can result in linear cause-effect relationships where each effect has one cause. Deep and exhaustive investigations are typically multimodal where effects have multiple causes (e.g. stress and stress for broken part).

   2. Cover all causes categories

      Functional – What is the function being affected? (e.g. Could not obtain the well data, for a wireline tool.) These can be easily identified by the user or operator.

      Physical — Tangible conditions or failures (e.g., “Resistivity pad dislodged from tool, three threads engaged instead of six”). Identification of these types of failure require some troubleshooting.

      Human — Actions or decisions leading to the physical cause (e.g., “Incorrect assembly torque applied”). Avoid stopping here, human error should not be tagged as the root cause.

      Systemic — Management system gaps that enabled the human factor (e.g., “No standard work instruction for assembly torque”). These are often the strongest risk prevention leverage points.

   3. Validate or Reject Causes

      Use direct evidence (measurement, inspection, observation) and circumstantial evidence (records, interviews, historical data).

      Possible outcomes:

      • Confirmed cause

      • Disproven cause

      • Unknown — requiring future monitoring or further study

3. Select Solutions

   Once possible causes are validated or rejected, identify which of the validated causes can be addressed within the organization’s capability and strategy.

   • Focus on fixes at the management system level for effective risk reduction. The organization may choose to also address human or physical causes based on cost/benefit analysis.

   • Some unknowns may require monitoring plans for future learning.

Summary

• Define problems from the perspective of business objectives.

• Ensure that you answer “What in the system made that human error possible or likely?”

• Verify cause-effect links with credible evidence.

• Select solutions based on cost/benefit analysis considering the competencies of the organization.

  

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.

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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 Luis.Suarez@tech-gopher.com if you want a copy of the document.