Towards Fine-Grained Citation Evaluation in Generated Text: A Comparative Analysis of Faithfulness Metrics
Weijia Zhang, Mohammad Aliannejadi, Yifei Yuan, Jiahuan Pei, Jia-Hong Huang, Evangelos Kanoulas
TL;DR
The paper tackles the problem of evaluating fine-grained citation support in generated text, where citations may fully, partially, or not support a statement. It proposes a comparative evaluation framework comprising correlation analysis, classification evaluation, and retrieval evaluation to assess faithfulness metrics across three support levels. Experimental results on GenSearch show that no single metric consistently outperforms others across all protocols; similarity-based metrics often fare better in retrieval, while entailment-based metrics can struggle with noise, and LLM-based metrics underperform overall. The work highlights protocol complementarity and offers practical recommendations—such as richer fine-grained training data and contrastive learning—to drive the development of more robust, explainable, and effective citation-faithfulness metrics with implications for grounded generation systems.
Abstract
Large language models (LLMs) often produce unsupported or unverifiable content, known as "hallucinations." To mitigate this, retrieval-augmented LLMs incorporate citations, grounding the content in verifiable sources. Despite such developments, manually assessing how well a citation supports the associated statement remains a major challenge. Previous studies use faithfulness metrics to estimate citation support automatically but are limited to binary classification, overlooking fine-grained citation support in practical scenarios. To investigate the effectiveness of faithfulness metrics in fine-grained scenarios, we propose a comparative evaluation framework that assesses the metric effectiveness in distinguishing citations between three-category support levels: full, partial, and no support. Our framework employs correlation analysis, classification evaluation, and retrieval evaluation to measure the alignment between metric scores and human judgments comprehensively. Our results show no single metric consistently excels across all evaluations, revealing the complexity of assessing fine-grained support. Based on the findings, we provide practical recommendations for developing more effective metrics.
