Simple and Principled Uncertainty Estimation with Deterministic Deep Learning via Distance Awareness
This addresses the need for efficient uncertainty estimation in real-time, industrial-scale applications, offering a practical alternative to existing methods.
The paper tackles the problem of high computational cost in Bayesian neural networks and deep ensembles for uncertainty estimation by proposing a single-model approach, SNGP, which achieves competitive performance with deep ensembles in prediction, calibration, and out-of-domain detection on vision and language tasks.
Bayesian neural networks (BNN) and deep ensembles are principled approaches to estimate the predictive uncertainty of a deep learning model. However their practicality in real-time, industrial-scale applications are limited due to their heavy memory and inference cost. This motivates us to study principled approaches to high-quality uncertainty estimation that require only a single deep neural network (DNN). By formalizing the uncertainty quantification as a minimax learning problem, we first identify input distance awareness, i.e., the model's ability to quantify the distance of a testing example from the training data in the input space, as a necessary condition for a DNN to achieve high-quality (i.e., minimax optimal) uncertainty estimation. We then propose Spectral-normalized Neural Gaussian Process (SNGP), a simple method that improves the distance-awareness ability of modern DNNs, by adding a weight normalization step during training and replacing the output layer with a Gaussian process. On a suite of vision and language understanding tasks and on modern architectures (Wide-ResNet and BERT), SNGP is competitive with deep ensembles in prediction, calibration and out-of-domain detection, and outperforms the other single-model approaches.