Calibration in Deep Learning: A Survey of the State-of-the-Art

Calibrating deep neural models plays an important role in building reliable, robust AI systems in safety-critical applications. Recent work has shown that modern neural networks that possess high predictive capability are poorly calibrated and produce unreliable model predictions. Though deep learning models achieve remarkable performance on various benchmarks, the study of model calibration and reliability is relatively underexplored. Ideal deep models should have not only high predictive performance but also be well calibrated. There have been some recent methods proposed to calibrate deep models by using different mechanisms. In this survey, we review the state-of-the-art calibration methods and provide an understanding of their principles for performing model calibration. First, we start with the definition of model calibration and explain the root causes of model miscalibration. Then we introduce the key metrics that can measure this aspect. It is followed by a summary of calibration methods that we roughly classified into four categories: post-hoc calibration, regularization methods, uncertainty estimation, and composition methods. We also covered some recent advancements in calibrating large models, particularly large language models (LLMs). Finally, we discuss some open issues, challenges, and potential directions.