Alert-Threshold Tuning

Measure continuous-audit alert precision, recall, and false positives.

Description

Alert precision and recall summarize labeled outcomes; tuning requires comparing actual thresholds separately.

Alert precision and recall summarize labeled outcomes; tuning requires comparing actual thresholds separately.1

Measure continuous-audit alert precision, recall, and false positives.

When to use Alert-Threshold Tuning

Use this tool to measure continuous-audit alert precision, recall, and false positives.

Prepare the documented facts, aligned totals or expected/observed evidence labels requested. Choose applicable requirements and thresholds separately before interpreting a planning screen.

How to use Alert-Threshold Tuning and understand its results

  1. Prepare the documented facts, aligned totals or expected/observed evidence labels requested. Choose applicable requirements and thresholds separately before interpreting a planning screen.
  2. Enter truePositiveAlerts, falsePositiveAlerts, missedEvents, minimumPrecisionPercent, minimumRecallPercent using the field table and calculation rules, then run the tool.
  3. Read precisionPercent, recallPercent, falsePositivePercent, meetsTargets. The explanation below defines the units, signs, ordering and any flags or placeholder values.
  4. If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
Input fieldMeaningValue type; see rules belowRequirement
truePositiveAlertsTrue-positive alertsinteger; minimum: 0Required
falsePositiveAlertsFalse-positive alertsinteger; minimum: 0Required
missedEventsKnown missed eventsinteger; minimum: 0Required
minimumPrecisionPercentMinimum precision (%)number; minimum: 0; maximum: 100Required
minimumRecallPercentMinimum recall (%)number; minimum: 0; maximum: 100Required

Enter nonnegative integer counts with at least one alert and one known event, minimum percentages 0–100. Return percentages, FP share of alerts and inclusive two-target gate.

precision=TP/(TP+FP); recall=TP/(TP+missed)

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output fieldMeaningValue type
precisionPercentAlert precision (%)number; minimum: 0; maximum: 100
recallPercentAlert recall (%)number; minimum: 0; maximum: 100
falsePositivePercentFalse-positive share (%)number; minimum: 0; maximum: 100
meetsTargetsMeets supplied precision and recall targetsboolean
json
{
  "input": {
    "truePositiveAlerts": 80,
    "falsePositiveAlerts": 20,
    "missedEvents": 20,
    "minimumPrecisionPercent": 75,
    "minimumRecallPercent": 75
  },
  "output": {
    "precisionPercent": 80,
    "recallPercent": 80,
    "falsePositivePercent": 20,
    "meetsTargets": true
  }
}

Limitations and assumptions

FP share is not false-positive rate among true negatives. No threshold search, event labeling or system execution is performed.

Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.

Alternative or Complementary methods

Use Disparate Impact: Calculate selection-rate disparity against a caller-supplied ratio threshold. For a complementary task, use Inherent Risk Score: Combine inherent-risk factors into a weighted score.

References

  1. Alert-Threshold Tuning — tool.io

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