Probability and Impact Matrix Guide for PMI-RMP
Why the Probability and Impact Matrix is Important
The Probability and Impact Matrix (P-I Matrix) is a critical tool in project risk management that helps prioritize risks based on their potential severity. Its importance stems from several key factors:
• It provides a visual framework for evaluating risks consistently
• It enables efficient allocation of resources to the most critical risks
• It facilitates standardized risk assessment across projects
• It helps teams focus on risks that truly matter to project objectives
• It's a required knowledge area for the PMI-RMP exam
What is a Probability and Impact Matrix?
A Probability and Impact Matrix is a grid that maps the likelihood of risks occurring (probability) against their potential effect on project objectives (impact). The matrix typically uses:
• Probability scales (e.g., Very Low to Very High, or numerical percentages)
• Impact scales (e.g., Very Low to Very High, or numerical values)
• Color-coded zones (typically red, yellow, green) representing risk severity
The resulting matrix forms the foundation of qualitative risk analysis, allowing project managers to categorize risks as high, medium, or low priority.
How the Probability and Impact Matrix Works
1. Define the Scales: Establish consistent scales for probability and impact, typically using 5 points (Very Low, Low, Medium, High, Very High)
2. Assign Values: For each identified risk, assign a probability rating and an impact rating based on the defined scales
3. Plot on Matrix: Place each risk on the matrix according to its probability and impact ratings
4. Calculate Risk Score: Multiply probability and impact values to calculate a risk score for each risk
5. Determine Thresholds: Establish thresholds for high, medium, and low-priority risks
6. Prioritize Risks: Focus attention and resources on addressing high-priority risks first
Example of a Probability and Impact Matrix
A typical 5×5 matrix might look like this:
• Probability levels: Very Low (0.1), Low (0.3), Medium (0.5), High (0.7), Very High (0.9)
• Impact levels: Very Low (0.05), Low (0.1), Medium (0.2), High (0.4), Very High (0.8)
• Risk score = Probability × Impact
• Risk categories: High (red) > 0.18, Medium (yellow) 0.05-0.18, Low (green) < 0.05
Exam Tips: Answering Questions on Probability and Impact Matrix
1. Understand the Calculation: Remember that risk score = probability × impact. Practice calculating risk scores quickly.
2. Know the Standard Scales: Familiarize yourself with the standard PMI scales for probability (0.1, 0.3, 0.5, 0.7, 0.9) and impact (0.05, 0.1, 0.2, 0.4, 0.8).
3. Recognize the Zones: High-priority risks (red zone) need immediate response plans. Medium-priority risks (yellow zone) should be monitored. Low-priority risks (green zone) may simply be accepted.
4. Consider Multiple Impacts: Remember that a risk can have different impacts on different project objectives (cost, schedule, scope, quality).
5. Apply to Opportunities: The matrix can be used for positive risks (opportunities) as well as threats.
6. Context Matters: The organization's risk appetite and project constraints influence how the matrix is interpreted.
7. Risk Thresholds: Be clear about what constitutes the thresholds between high, medium, and low-priority risks.
8. Process Integration: Understand how the P-I Matrix fits into the overall risk management process, particularly Perform Qualitative Risk Analysis.
9. Time-Sensitivity: Consider that some risks with lower scores might need attention if they could occur imminently.
10. Visual Representation: Be able to visualize and interpret the matrix from written descriptions in exam questions.
By mastering these concepts and practicing with sample matrices, you'll be well-prepared to answer PMI-RMP exam questions about the Probability and Impact Matrix confidently.