Differences among ROUGE, BLEU, and BERTScore

Remember the representative metrics for text generation evaluation.
・ROUGE: For summarization evaluation, counts the overlap of words and n-grams with a reference summary (surface-match based).
・BLEU: For machine translation evaluation, looks at n-gram matching with a reference translation (surface-match based).
・BERTScore: Converts generated and reference text into embeddings (vectors) and evaluates by semantic closeness (robust to paraphrasing).
The surface-match ROUGE and BLEU are weak against paraphrasing; when you want to evaluate by semantic closeness, use BERTScore.