CRISC IT Risk Assessment Practice Question
In the FAIR framework, Loss Event Frequency (LEF) is calculated as:
⚠ Common exam trap
CRISC often tests the FAIR formula by mixing it with traditional ALE (ARO × SLE); candidates who memorize ALE but not FAIR's decomposition pick the ARO × SLE option.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Threat Event Frequency × Vulnerability
In the FAIR (Factor Analysis of Information Risk) framework, Loss Event Frequency (LEF) is the probable frequency of loss events in a given timeframe. It is derived by multiplying Threat Event Frequency (TEF) — how often a threat agent acts — by Vulnerability, which is the probability that a threat event becomes a loss event. This product yields LEF.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Threat Event Frequency + Vulnerability
Why it's wrong here
Threat Event Frequency plus Vulnerability is not the FAIR formula; LEF is derived by multiplying Threat Event Frequency by Vulnerability (the probability a threat event becomes a loss event). Addition is tempting because both factors feed LEF, but FAIR composes them multiplicatively, so summing them misstates risk magnitude.
- ✗
Annualized Rate of Occurrence × Single Loss Expectancy
Why it's wrong here
LEF measures how often loss events occur, so pairing a frequency rate with Single Loss Expectancy (a monetary magnitude) mixes the wrong axis; that product is actually Annualised Loss Expectancy. Annualised Rate of Occurrence belongs with vulnerability to derive LEF, making this tempting when frequency and impact terms are conflated.
- ✗
Loss Magnitude × Vulnerability
Why it's wrong here
Loss Magnitude measures the financial impact of a realised threat event, so multiplying it by Vulnerability produces a magnitude-weighted figure, not a frequency. FAIR derives LEF from Threat Event Frequency and Vulnerability. Loss Magnitude belongs to the risk calculation, combined with LEF to produce Annualised Loss Expectancy — tempting because both factors genuinely appear in FAIR.
- ✓
Threat Event Frequency × Vulnerability
Why this is correct
FAIR decomposes Loss Event Frequency into Threat Event Frequency multiplied by Vulnerability, where Vulnerability is the probability that a threat event becomes a loss event. This differs from Loss Magnitude, which is a separate factor in the risk calculation.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISACA exam blueprint
This CRISC practice question is part of Courseiva's free ISACA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CRISC exam.