Recent works have shown that language models (LM) capture different types of knowledge regarding facts or common sense. However, because no model is perfect, they still fail to provide appropriate answers in many cases. In this paper, we ask the question "how can we know when language models know, with confidence, the answer to a particular query?" We examine this question from the point of view of calibration, the property of a probabilistic model's predicted probabilities actually being well correlated with the probability of correctness. We first examine a state-of-the-art generative QA model, T5, and examine whether its probabilities are well calibrated, finding the answer is a relatively emphatic no. We then examine methods to calibrate such models to make their confidence scores correlate better with the likelihood of correctness through fine-tuning, post-hoc probability modification, or adjustment of the predicted outputs or inputs. Experiments on a diverse range of datasets demonstrate the effectiveness of our methods. We also perform analysis to study the strengths and limitations of these methods, shedding light on further improvements that may be made in methods for calibrating LMs.

本文研究从校准的角度考察自然语言模型(T5、BART、GPT-2)的知识储备，找到可靠性评估，提高其置信度与正确概率的相关性的方法。实验数据表明，校准可以让模型的表现得到提高。

语言模型何时知道？关于语言模型在问答任务中的校准问题