揭示自动评估中人类不确定性对相关性误判的影响,提出分层分析与新度量方法
Beyond correlation: The Impact of Human Uncertainty in Measuring the Effectiveness of Automatic Evaluation and LLM-as-a-Judge
- 按人类标签不确定性分层数据,突破单一相关性指标局限
- 发现当人类标签不一致时,机器标签相关性看似良好,实则掩盖差异
- 提出感知型分箱JS散度和可视化图表,适用于偏好类评价场景
生成模型的自动评估有效性通常通过自动化标签与人工标签的相关性来衡量。然而,如Krippendorff's α和Randolph's κ等指标原本用于评估人类标注的一致性,其对人类行为的假设未必适用于机器生成标签。本文指出,仅依赖单一聚合相关性分数会掩盖人类标签与自动评估标签之间的根本差异,包括LLM-as-a-Judge的结果。当样本中人类标注存在较高变异性或不确定性时,机器标签与人类多数标签的相关性看似接近或优于人-人相关性(HH),造成机器标签能代表人类多数的假象。但随着一致性人类标签比例上升,机器与人类标签的相关性显著低于HH相关性。基于此,我们首先提出按人类标签不确定性分层数据以实现更稳健的分析;其次,鉴于感知类评价(如态度、偏好)天然包含不确定性,引入一种新度量——用于感知场景的分箱Jensen-Shannon散度(binned Jensen-Shannon Divergence for perception),以更准确衡量自动评估效果。我们还设计了感知图(perception charts)用于合理呈现相关性度量结果。代码已开源:https://github.com/amazon-science/BeyondCorrelation。
原文摘要 · Abstract (English)
The effectiveness of automatic evaluation of generative models is typically measured by comparing the labels generated via automation with labels by humans using correlation metrics. However, metrics like Krippendorff's $α$ and Randolph's $κ$ were originally designed to measure the reliability of human labeling, thus make assumptions about typical human labeling behavior, and these assumptions may not be applicable to machine generated labels. In this paper, we show how *relying on a single aggregate correlation score* can obscure fundamental differences between human labels and those from automatic evaluation, including LLM-as-a-Judge. Specifically, we demonstrate that when the proportion of samples with variation or uncertainty in human assigned labels is relatively high, machine labels (generated by automatic evaluation methods) may superficially appear to have similar or better correlation with the human majority label compared to the human-to-human (HH) correlation. This can create the illusion that labels from automatic evaluation approximates the human majority label. However, as the proportion of samples with consistent human labels increases, the correlation between machine and human labels fall well below HH correlation. Based on these findings, we first propose stratifying data by human label uncertainty to provide a more robust analysis of automatic evaluation performance. Second, recognizing that uncertainty and variation are inherent in perception-based human evaluations, such as those involving attitudes or preferences, we introduce a new metric - binned Jensen-Shannon Divergence for perception for such scenarios to better measure the effectiveness of automatic evaluations. We present visualization techniques -- perception charts, to contextualize correlation measures appropriately. We have open-sourced at https://github.com/amazon-science/BeyondCorrelation.
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