2020

How Good is the Bayes Posterior in Deep Neural Networks Really?

Wenzel, Florian, Roth, Kevin, Veeling, Bastiaan S. et al.

Understand

During the past five years the Bayesian deep learning community has developed increasingly accurate and efficient approximate inference procedures that allow for Bayesian inference in deep neural networks.

  • However, despite this algorithmic progress and the promise of improved uncertainty quantification and sample efficiency there are---as of early 2020---no publicized deployments of Bayesian neural networks in industrial practice.
  • In this work we cast doubt on the current understanding of Bayes posteriors in popular deep neural networks: we demonstrate through careful MCMC sampling that the posterior predictive induced by the Bayes posterior yields systematically worse predictions compared to simpler methods including point estimates obtained from SGD.
  • Furthermore, we demonstrate that predictive performance is improved significantly through the use of a "cold posterior" that overcounts evidence.

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