What is called the percentage at which the False Rejection Rate equals the False Acceptance Rate?

Question

Options

• AFalse Rejection Rate (FRR) or Type I Error
• BFalse Acceptance Rate (FAR) or Type II Error
• CCrossover Error Rate (CER)
• DFailure to enroll rate (FTE or FER)

• B
  2% (1)
• C
  93% (41)
• D
  5% (2)

Explanation

Crossover Error Rate (CER) is the specific metric that identifies the point where FRR and FAR are equal - it serves as a standard benchmark for comparing the overall accuracy of biometric systems. A lower CER indicates a more accurate system, making it the go-to figure for vendor comparisons.

Why the distractors are wrong:

• A (FRR / Type I Error): FRR measures how often legitimate users are incorrectly rejected - one half of the equation, not the crossover point itself.
• B (FAR / Type II Error): FAR measures how often impostors are incorrectly accepted - the other half, again not the crossover point.
• D (FTE/FER): Failure to Enroll Rate describes how often a system fails to register a user's biometric at all - a separate concept unrelated to acceptance/rejection thresholds.

Memory tip: Think of CER as the "crossing" point on a graph where the FRR line and FAR line cross over each other - the name literally describes the visual. It's also sometimes called the Equal Error Rate (EER), so watch for that synonym on exams.

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