Understanding Dataset Difficulty with \(\mathcal{V}\)-Usable Information

• Published in: arXiv.org 2022-06
• Main Authors: Kawin Ethayarajh, Choi, Yejin, Swayamdipta, Swabha
• Format: Article
• Language: English
• Subjects: Annotations; Datasets; Information theory
• ISSN: 2331-8422

Estimating the difficulty of a dataset typically involves comparing state-of-the-art models to humans; the bigger the performance gap, the harder the dataset is said to be. However, this comparison provides little understanding of how difficult each instance in a given distribution is, or what attributes make the dataset difficult for a given model. To address these questions, we frame dataset difficulty -- w.r.t. a model \(\mathcal{V}\) -- as the lack of \(\mathcal{V}\)-\(\textit{usable information}\) (Xu et al., 2019), where a lower value indicates a more difficult dataset for \(\mathcal{V}\). We further introduce \(\textit{pointwise \)\mathcal{V}\(-information}\) (PVI) for measuring the difficulty of individual instances w.r.t. a given distribution. While standard evaluation metrics typically only compare different models for the same dataset, \(\mathcal{V}\)-\(\textit{usable information}\) and PVI also permit the converse: for a given model \(\mathcal{V}\), we can compare different datasets, as well as different instances/slices of the same dataset. Furthermore, our framework allows for the interpretability of different input attributes via transformations of the input, which we use to discover annotation artefacts in widely-used NLP benchmarks.