F0.5-Measure

An F0.5-Measure is an F-measure where the β is equal to 0.5.

• AKA: [math]\displaystyle{ F_{0.5} }[/math].
• Context:
  • It can be calculated as:
    • [math]\displaystyle{ F_{0.5} }[/math] = (1 + 0.5²) / ((1/P) + (0.5²/R)).
    • [math]\displaystyle{ F_{0.5} }[/math] = 1.25PR / (0.25R + P).
    • [math]\displaystyle{ F_{0.5} }[/math] = 1.25TP / (1.25TP + 0.25FN + FP).
  • It can (typically) place more emphasis on P than R, making it more useful in situations where false positives are more costly.
  • It can (often) be used in scenarios like information retrieval or email spam filtering, where it's more critical to retrieve highly relevant items (high precision) than to retrieve most relevant items (high recall).
  • ...
• Counter-Example(s):
  • an F1-Measure.
  • an F2-Measure.
• See: Harmonic Mean, Precision, Recall, True Positive, False Positive, False Negative.

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