arXiv:2410.17413cs.CL2024-10ICLR被引 35

提出可扩展的训练数据溯源方法,实现对80亿参数大模型的全规模影响分析。

Scalable Influence and Fact Tracing for Large Language Model Pretraining

  • 改进梯度法,结合优化器修正与特定任务海森近似,实现大规模训练数据溯源。
  • 在1600亿词元语料中精准定位影响模型输出的关键训练样本。
  • 揭示事实归属与因果影响的差异,适合模型透明性与数据质量研究者。

训练数据溯源(TDA)旨在将模型输出追溯到具体训练样本,应用于大语言模型可显著提升模型透明度与数据管理能力。然而,现有方法难以适用于大模型预训练的全规模数据。本文改进基于梯度的方法,在无需子采样或预过滤的前提下,成功从超过160B tokens的语料中为一个8B参数语言模型检索出关键影响样本。所提方法结合优化器状态修正、任务特异性海森近似与归一化编码,三者对大规模性能至关重要。在事实溯源任务的定量评估中,本方法在识别影响模型预测的样本上表现最佳,而传统无模型方法如BM25在寻找明确包含相关事实的段落时更优。结果表明事实归属与因果影响之间存在错位;随着模型规模和训练数据增加,影响与事实归属趋于一致。进一步分析发现,影响样本不仅直接蕴含特定事实,还通过强化关系类型、常见实体与名称等先验知识支持输出。我们公开了提示集、模型输出及可视化工具,支持探索8B参数模型在事实推理、常识、算术与开放生成中的影响样本。

原文摘要 · Abstract (English)

Training data attribution (TDA) methods aim to attribute model outputs back to specific training examples, and the application of these methods to large language model (LLM) outputs could significantly advance model transparency and data curation. However, it has been challenging to date to apply these methods to the full scale of LLM pretraining. In this paper, we refine existing gradient-based methods to work effectively at scale, allowing us to retrieve influential examples for an 8B-parameter language model from a pretraining corpus of over 160B tokens with no need for subsampling or pre-filtering. Our method combines several techniques, including optimizer state correction, a task-specific Hessian approximation, and normalized encodings, which we find to be critical for performance at scale. In quantitative evaluations on a fact tracing task, our method performs best at identifying examples that influence model predictions, but classical, model-agnostic retrieval methods such as BM25 still perform better at finding passages which explicitly contain relevant facts. These results demonstrate a misalignment between factual *attribution* and causal *influence*. With increasing model size and training tokens, we find that influence more closely aligns with factual attribution. Finally, we examine different types of examples identified as influential by our method, finding that while many directly entail a particular fact, others support the same output by reinforcing priors on relation types, common entities, and names. We release our prompt set and model outputs, along with a web-based visualization tool to explore influential examples for factual predictions, commonsense reasoning, arithmetic, and open-ended generation for an 8B-parameter LLM.

大模型数据溯源模型透明影响分析

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