Metric List

Automatic metrics for multiple-choice tasks

These metrics use log-likelihood of the different possible targets.

• loglikelihood_acc: Fraction of instances where the choice with the best logprob was correct - we recommend using a normalization by length
• loglikelihood_f1: Corpus level F1 score of the multichoice selection
• mcc: Matthew’s correlation coefficient (a measure of agreement between statistical distributions).
• recall_at_k: Fraction of instances where the choice with the k-st best logprob or better was correct
• mrr: Mean reciprocal rank, a measure of the quality of a ranking of choices ordered by correctness/relevance
• target_perplexity: Perplexity of the different choices available.
• acc_golds_likelihood: A bit different, it actually checks if the average logprob of a single target is above or below 0.5.
• multi_f1_numeric: Loglikelihood F1 score for multiple gold targets.

Automatic metrics for perplexity and language modeling

These metrics use log-likelihood of prompt.

• word_perplexity: Perplexity (log probability of the input) weighted by the number of words of the sequence.
• byte_perplexity: Perplexity (log probability of the input) weighted by the number of bytes of the sequence.
• bits_per_byte: Average number of bits per byte according to model probabilities.
• log_prob: Predicted output’s average log probability (input’s log prob for language modeling).

Automatic metrics for generative tasks

These metrics need the model to generate an output. They are therefore slower.

• Base:
  • exact_match: Fraction of instances where the prediction matches the gold. Several variations can be made through parametrization:
    • normalization on string pre-comparision on whitespace, articles, capitalization, …
    • comparing the full string, or only subsets (prefix, suffix, …)
  • maj_at_k: Model majority vote. Samples k generations from the model and assumes the most frequent is the actual prediction.
  • f1_score: Average F1 score in terms of word overlap between the model output and gold (normalisation optional).
  • f1_score_macro: Corpus level macro F1 score.
  • f1_score_macro: Corpus level micro F1 score.
• Summarization:
  • rouge: Average ROUGE score (Lin, 2004).
  • rouge1: Average ROUGE score (Lin, 2004) based on 1-gram overlap.
  • rouge2: Average ROUGE score (Lin, 2004) based on 2-gram overlap.
  • rougeL: Average ROUGE score (Lin, 2004) based on longest common subsequence overlap.
  • rougeLsum: Average ROUGE score (Lin, 2004) based on longest common subsequence overlap.
  • rouge_t5 (BigBench): Corpus level ROUGE score for all available ROUGE metrics.
  • faithfulness: Faithfulness scores based on the SummaC method of Laban et al. (2022).
  • extractiveness: Reports, based on (Grusky et al., 2018):
    • summarization_coverage: Extent to which the model-generated summaries are extractive fragments from the source document,
    • summarization_density: Extent to which the model-generated summaries are extractive summaries based on the source document,
    • summarization_compression: Extent to which the model-generated summaries are compressed relative to the source document.
  • bert_score: Reports the average BERTScore precision, recall, and f1 score (Zhang et al., 2020) between model generation and gold summary.
• Translation:
  • bleu: Corpus level BLEU score (Papineni et al., 2002) - uses the sacrebleu implementation.
  • bleu_1: Average sample BLEU score (Papineni et al., 2002) based on 1-gram overlap - uses the nltk implementation.
  • bleu_4: Average sample BLEU score (Papineni et al., 2002) based on 4-gram overlap - uses the nltk implementation.
  • chrf: Character n-gram matches f-score.
  • ter: Translation edit/error rate.
• Copyright:
  • copyright: Reports:
    • longest_common_prefix_length: Average length of longest common prefix between model generation and reference,
    • edit_distance: Average Levenshtein edit distance between model generation and reference,
    • edit_similarity: Average Levenshtein edit similarity (normalized by the length of longer sequence) between model generation and reference.
• Math:
  • Both exact_match and maj_at_k can be used to evaluate mathematics tasks with math specific normalization to remove and filter latex.

LLM-as-Judge

• llm_judge_gpt3p5: Can be used for any generative task, the model will be scored by a GPT3.5 model using the OpenAI API.
• llm_judge_llama_3_405b: Can be used for any generative task, the model will be scored by a Llama 3.405B model using the HuggingFace API.
• llm_judge_multi_turn_gpt3p5: Can be used for any generative task, the model will be scored by a GPT3.5 model using the OpenAI API. It is used for multiturn tasks like mt-bench.
• llm_judge_multi_turn_llama_3_405b: Can be used for any generative task, the model will be scored by a Llama 3.405B model using the HuggingFace API. It is used for multiturn tasks like mt-bench.

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