Root Cause Analysis: Identifying Underlying Reasons for Variances, Defects, and Risks

PMBOK v8 Definition

Root cause analysis is an analytical method used to determine the basic underlying reason that causes a variance, defect, or risk. A root cause may underlie more than one variance, defect, or risk. When all root causes for a problem are removed, the problem does not recur. This technique is also used for identifying the root causes of a problem and solving them.

Why It Matters for the Exam

Root cause analysis appears frequently on the PMI exam in questions about quality management, risk management, and problem-solving scenarios. Exam questions typically test your ability to distinguish root cause analysis from other analytical techniques, understand when to apply it in the project life cycle, and recognize its role in preventing problem recurrence.

Key Points to Remember (for the exam)

• Core Purpose: Determines the basic underlying reason causing a variance, defect, or risk
• Critical Outcome: When all root causes are removed, the problem does not recur
• Multi-Problem Connection: One root cause may underlie more than one variance, defect, or risk
• Application Scope: Used as a technique for identifying root causes of problems AND solving them
• Life Cycle Application: Applied throughout the project, with increasing detail as information becomes available
• Risk Categories: Risks can be categorized by common root causes to develop more effective risk responses
• Relationship to Progressive Elaboration: During early strategic planning, work packages are outlined at a high level; as more information becomes available, these are decomposed into detailed activities

Typical PMI Exam Example

A project manager discovers that three different work packages have experienced quality defects. After investigating, she finds that all three defects originated from the same supplier's raw material batch. The project manager applies root cause analysis to identify the supplier's quality control process failure as the basic underlying reason. She then implements corrective actions with the supplier to prevent recurrence.

PMI Exam Traps

• Trap: Confusing root cause analysis with cause-and-effect diagrams

• Reality: Root cause analysis is the analytical method; cause-and-effect diagrams are one tool that can support this analysis

• Trap: Thinking root cause analysis only applies to defects

• Reality: Root cause analysis applies to variances, defects, AND risks

• Trap: Assuming removing one root cause solves all related problems

• Reality: A root cause may underlie multiple problems, but you must ensure ALL root causes are removed for the problem to not recur

• Trap: Believing root cause analysis is a one-time activity at project start

• Reality: Risk identification and analysis, including root cause analysis, should be an iterative process throughout the project life cycle

Important PMI Connections

Quick Review Questions

1. What is the primary purpose of root cause analysis in project management?

2. If a project team removes one root cause but the problem still occurs, what does this indicate?

3. How does the level of detail in root cause analysis change as the project progresses through its life cycle?

4. Why might a project manager categorize risks by common root causes?

5. What is the relationship between root cause analysis and problem recurrence?

PMBOK v8 Reference

Section 2.7.2.3 - Perform Risk Analysis (Root cause analysis as analytical method for determining underlying reasons causing variances, defects, or risks)

Section 2.3 - Perform Risk Analysis (Root cause analysis as technique applied throughout project life cycle with iterative process)