Probability and Impact Matrix with Scoring Scheme

PMBOK v8 Definition

The Probability and Impact Matrix is a tool used to evaluate each risk by combining its probability of occurrence with its potential impact on project objectives. According to PMBOK v8, this matrix "gives a probability-impact score for each risk, which allows the relative priority of individual risks to be evaluated within each priority level." It is applied during the Perform Quantitative Risk Analysis process within the Project Risk Management Knowledge Area.

Why It Matters for the Exam

The Probability and Impact Matrix appears frequently in PMI exam questions testing your ability to prioritize risks and understand scoring schemes. Questions often ask you to interpret matrix values, determine risk priority levels, or identify which risks require immediate response based on their probability-impact scores.

Key Points to Remember (for the exam)

Main Purpose: Evaluates relative priority of individual risks within each priority level
Key Components: Probability (likelihood of occurrence) × Impact (effect on objectives) = Risk Score
Scoring Scheme: Numeric values assigned to probability and impact levels (e.g., 1-5 scale)
Priority Levels: Typically color-coded (Red=High priority, Yellow=Medium priority, Green=Low priority)
Common Confusion: Do NOT confuse Probability and Impact Matrix (qualitative analysis) with expected monetary value calculations (quantitative analysis)
Critical Distinction: The matrix ranks risks within priority levels, not across all risks globally
Output: Provides a prioritized list of risks for further analysis or response planning

Typical PMI Exam Example

A project manager evaluates two risks: Risk A has a probability of 0.8 and impact of 4 on a 1-5 scale (score=3.2), while Risk B has probability 0.3 and impact 5 (score=1.5). Using the Probability and Impact Matrix, Risk A receives higher priority. The project manager documents both risks in the risk register and plans responses accordingly.

PMI Exam Traps

Trap: Assuming all risks with high impact automatically have high priority
- Reality: Priority is determined by probability × impact score, not impact alone
Trap: Confusing the Probability and Impact Matrix (qualitative) with sensitivity analysis (quantitative)
- Reality: The matrix ranks risks; sensitivity analysis determines which risks have most potential impact on outcomes
Trap: Thinking the matrix replaces the risk register
- Reality: The matrix is a tool within risk analysis; results feed into the risk register
Trap: Believing the scoring scheme is standardized across all organizations
- Reality: Organizations define their own probability and impact scales and scoring thresholds

Important PMI Connections

Related Concept	Relationship Type	Exam Attention Point
Risk Register	Output of risk analysis	Matrix results are documented in the risk register
Perform Quantitative Risk Analysis	Process where matrix is used	Matrix is a tool in quantitative analysis
Risk Response Planning	Follow-up activity	High-priority risks from matrix trigger response planning
Problem-Solving	Complementary technique	Systematic problem-solving addresses issues identified through risk analysis
Quality Management	Related domain	Problem-solving methods (define problem, identify root cause, generate solutions, implement, verify) support quality improvement

Quick Review Questions

A risk has probability 0.6 and impact 3 on a 1-5 scale. What is its probability-impact score?
In the Probability and Impact Matrix, what does the color red typically indicate?
True or False: The Probability and Impact Matrix is used during Perform Quantitative Risk Analysis.
A project manager identifies two risks with scores of 4.2 and 2.8. Which risk receives higher priority?
What is the primary purpose of the scoring scheme in the Probability and Impact Matrix?

PMBOK v8 Reference

Section 5, Tools and Techniques, pages 187-188 (Figure 5-14: Example Probability and Impact Matrix With Scoring Scheme)