Bayesian neural networks (BNNs) hold great promise as a flexible and principled solution to deal with uncertainty when learning from finite data. Among approaches to realize probabilistic inference in deep neural networks, variational Bayes (VB) is theoretically grounded, generally applicable, and computationally efficient. With wide recognition of potential advantages, why is it that variational Bayes has seen very limited practical use for BNNs in real applications? We argue that variational inference in neural networks is fragile: successful implementations require careful initialization and tuning of prior variances, as well as controlling the variance of Monte Carlo gradient estimates. We fix VB and turn it into a robust inference tool for Bayesian neural networks. We achieve this with two innovations: first, we introduce a novel deterministic method to approximate moments in neural networks, eliminating gradient variance; second, we introduce a hierarchical prior for parameters and a novel empirical Bayes procedure for automatically selecting prior variances. Combining these two innovations, the resulting method is highly efficient and robust. On the application of heteroscedastic regression we demonstrate strong predictive performance over alternative approaches.

本研究提出两种创新方法以将变分贝叶斯转化为贝叶斯神经网络的稳健推理工具：一种新的确定性方法用于逼近神经网络的矩，消除了梯度方差；一种参数的分层先验和自动选择先验方差的新的经验贝叶斯程序。将这两种方法结合起来，所得到的方法高效而稳健，在异方差回归应用中表现出了很好的预测性能。

鲁棒贝叶斯神经网络的确定性变分推断