Question 33
Domain 2: Core Machine Learning, AI, and Transformer FoundationsIn text classification tasks, what does F1-score measure?
Correct answer: C
Explanation
F1-score measures the balance between precision and recall by combining them into a single metric. It is defined as the "harmonic mean of precision and recall," which gives a low score when either precision or recall is low.
Why each option is right or wrong
A. Only precision
B. Only recall
C. Harmonic mean of precision and recall
The F1-score is defined mathematically as 2PR/(P+R), where P is precision and R is recall, so it is the harmonic mean of those two rates. In text classification, this is the standard single-number summary used when both false positives and false negatives matter, and it penalizes imbalance because the score drops sharply if either precision or recall is low.
D. Arithmetic mean of precision and recall