FEQA: A Question Answering Evaluation Framework for Faithfulness Assessment in Abstractive Summarization
Written for the Research library (claude-opus-5-5) from the paper text. Original — aclanthology.org/2020.acl-main.454.pdf
Summary
Neural abstractive summarizers often produce statements that the source article does not support, and standard metrics rarely catch these errors. Durmus, He and Diab study how faithful summaries are and propose FEQA, an automatic way to check it. They first had humans judge faithfulness for outputs from several systems (PGC, FastRL, BottomUp, TConv, BertSum) on CNN/DM and XSum. They also built a sentence-level scale of abstractiveness, running from copying a whole sentence to fusing pieces of several sentences. The judgments show a trade-off: the less a summary copies from the source, the more likely it is to contain errors. FEQA turns this into a test. It masks answer spans in each summary sentence and generates questions about them. A reading-comprehension model then answers those questions from the source document. If its answers don't match the masked spans, the summary probably contains unsupported content. FEQA was compared with metrics based on n-gram overlap, embeddings, entailment and relation extraction. It tracked human judgments best, and it was the only one that still did so on the highly abstractive XSum summaries. The result supports judging faithfulness separately from content selection.
Key points
- Datasets: CNN/DM has about 288k training examples and XSum about 204k. Reference summaries in CNN/DM mostly compress source sentences by dropping words. No XSum reference sentence is copied from a single source sentence, and about 96% of its trigrams are new.
- What drives abstractiveness: the training data matters more than the model architecture. The same systems are nearly extractive on CNN/DM but much more abstractive on XSum, though they still copy more than the human references.
- How FEQA works: a learned model generates questions from masked spans of the summary. An off-the-shelf QA model answers them from the source, and the answers are compared using token F1. The authors say other QA models and answer types could be used in place of these.
- Error analysis on 100 QA pairs: about 94% of the generated questions were acceptable. The QA model behaved correctly about 78% of the time. Most errors came from handling unanswerable questions wrongly, from long articles, and from exact-match F1 marking correct paraphrased answers as wrong.
- ROUGE: ROUGE against the reference summary correlates only weakly with faithfulness on CNN/DM and not significantly on XSum. The authors still advise checking final results with human evaluation.
Cited by
- CLIFF: Contrastive Learning for Improving Faithfulness and Factuality in Abstractive Summarization
- QAFactEval: Improved QA-Based Factual Consistency Evaluation for Summarization
- Evaluating Factuality in Generation with Dependency-level Entailment
- Annotating and Modeling Fine-grained Factuality in Summarization
- Evaluating Large Language Models: A Comprehensive Survey
- TRUE: Re-evaluating Factual Consistency Evaluation
- Efficient Attentions for Long Document Summarization
- A Survey on Hallucination in Large Language Models: Principles, Taxonomy, Challenges, and Open Questions
- Survey of Hallucination in Natural Language Generation
- Hurdles to Progress in Long-form Question Answering
- Revisiting the Gold Standard: Grounding Summarization Evaluation with Robust Human Evaluation
- ChatGPT as a Factual Inconsistency Evaluator for Text Summarization
- Understanding Factuality in Abstractive Summarization with FRANK: A Benchmark for Factuality Metrics
- QuALITY: Question Answering with Long Input Texts, Yes!
- QuestEval: Summarization Asks for Fact-based Evaluation
- Beyond the Imitation Game: Quantifying and extrapolating the capabilities of language models
- AlignScore: Evaluating Factual Consistency with A Unified Alignment Function
- Siren's Song in the AI Ocean: A Survey on Hallucination in Large Language Models
Cite
@inproceedings{durmus2020feqa,
title = {{FEQA: A Question Answering Evaluation Framework for Faithfulness Assessment in Abstractive Summarization}},
author = {Durmus, Esin and He, He and Diab, Mona},
booktitle = {Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics},
year = {2020},
doi = {10.18653/v1/2020.acl-main.454},
eprint = {2005.03754},
archivePrefix = {arXiv},
url = {https://doi.org/10.18653/v1/2020.acl-main.454}
}References
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