Risk Probability and Impact Assessment Using Plan Definitions
PMBOK v8 Definition
Risk probability and impact assessment is the process of evaluating the likelihood that a specific risk will occur and the potential effect on one or more project objectives such as schedule, cost, quality, or performance. These assessments are performed using the definitions given in the risk management plan, which provides specific definitions of probability and impact levels that are tailored to the project context and reflect the risk appetite and thresholds of the organization and key stakeholders. Impacts are negative for threats and positive for opportunities, and both probability and impact are assessed for each identified individual project risk.
Process Group: Planning
Knowledge Area: Project Risk Management
Why It Matters for the Exam
This concept appears frequently in PMI exam questions testing your understanding of how risks are evaluated and prioritized. Questions often focus on the source of assessment definitions (risk management plan), who participates in assessments, and how probability and impact levels are determined. Expect scenario-based questions where you must identify the correct next step or recognize when probability and impact definitions are being applied incorrectly.
Key Points to Remember (for the exam)
- Definition Source: Risk probabilities and impacts are assessed using the definitions given in the risk management plan — not the risk register, not organizational process assets
- Assessment Participants: Project team members and knowledgeable persons external to the project are included in interviews or meetings
- Participant Selection Criteria: Participants are selected for their familiarity with the types of risk recorded in the risk register
- Level of Detail: The number of levels reflects the degree of detail required — more levels for a detailed approach (typically five levels), fewer for a simple process (usually three levels)
- Explanatory Detail: Assumptions justifying the levels assigned are recorded along with the assessment
- Low Priority Risks: Risks with low probability and impact may be included in the risk register as part of a watch list for future monitoring
- Scoring Method: Where numeric values are used, they can be multiplied to give a probability–impact score for each risk, allowing relative priority evaluation within each priority level
Typical PMI Exam Example
A project manager is facilitating a risk assessment workshop. The team evaluates the probability of a key supplier delay as 0.6 (on a 0.1–1.0 scale) and the schedule impact as 0.8 (on a 0.1–1.0 scale). The project manager multiplies these values to get a probability-impact score of 0.48. Where did the definitions for these probability and impact levels originate?
Answer: The risk management plan
PMI Exam Traps
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Trap: Confusing the risk management plan with the risk register as the source of probability and impact definitions
Reality: The risk management plan defines the probability and impact levels; the risk register records the assessed risks -
Trap: Thinking only project team members participate in risk assessments
Reality: Knowledgeable persons external to the project are also included -
Trap: Assuming all risks with low probability and impact are removed from the risk register
Reality: They may be included as part of a watch list for future monitoring -
Trap: Believing probability and impact definitions are always numeric
Reality: Descriptive terms (such as very high, high, medium, low, and very low) or numeric values can be used
Important PMI Connections
| Related Concept | Relationship Type | Exam Attention Point |
|---|---|---|
| Risk Management Plan | Defines probability and impact levels | Always check this plan first when asked about assessment criteria |
| Risk Register | Records assessed risks | Contains the watch list for low-priority risks |
| Risk Appetite and Thresholds | Influences definition levels | Definitions reflect organizational risk appetite and thresholds |
| Perform Qualitative Risk Analysis | Process that uses these assessments | Probability and impact assessment is a key technique within this process |
Quick Review Questions
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Where are the definitions for risk probability and impact levels documented?
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Which participants are selected for risk probability and impact assessment interviews or meetings?
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What happens to risks assessed with low probability and low impact?
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When numeric values are used for probability and impact, how is relative priority determined?
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How does the number of probability and impact levels relate to the project's risk approach?
PMBOK v8 Reference
Section 2.7.2 - Plan Risk Management
Section 2.7.2.3 - Perform Qualitative Risk Analysis (Risk probability and impact assessment)