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arXiv 2005.04987cs.LGcs.AIstat.ML
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先验选择对贝叶斯神经网络识别未知量能力的影响

Prior choice affects ability of Bayesian neural networks to identify unknowns

University of Fribourg(弗里堡大学);Swiss Institute of Bioinformatics(瑞士生物信息学研究所);University of Gothenburg(哥德堡大学);Gothenburg Global Biodiversity Center(哥德堡全球生物多样性中心)

Daniele Silvestro, Tobias Andermann

摘要:

深度贝叶斯神经网络(BNN)是一种强大的工具,虽然计算要求很高,但可以在联合估计预测不确定性的同时执行参数估计。BNN通常使用模型参数的任意正态分布先验分布来实现。在这里,我们探讨了不同的先验分布对BNN分类任务的影响,并评估了支持基于马尔可夫链蒙特卡罗抽样和计算贝叶斯因子近似的后验概率预测的证据。我们表明,先验的选择有很大的影响模型的能力,自信地分配数据到正确的类(真阳性率)。先验选择也会显著影响BNN将分布外实例识别为未知(假阳性率)的能力。当将我们的结果与具有Monte Carlo丢弃的神经网络(NN)进行比较时,我们发现BNN通常优于NN。最后,在我们的测试中,我们没有找到一个最佳选择作为先验分布。相反,每个数据集在不同的先验下都产生了最佳结果,这表明测试替代选项可以提高BNN的性能。

英文摘要:

Deep Bayesian neural networks (BNNs) are a powerful tool, though computationally demanding, to perform parameter estimation while jointly estimating uncertainty around predictions. BNNs are typically implemented using arbitrary normal-distributed prior distributions on the model parameters. Here, we explore the effects of different prior distributions on classification tasks in BNNs and evaluate the evidence supporting the predictions based on posterior probabilities approximated by Markov Chain Monte Carlo sampling and by computing Bayes factors. We show that the choice of priors has a substantial impact on the ability of the model to confidently assign data to the correct class (true positive rates). Prior choice also affects significantly the ability of a BNN to identify out-of-distribution instances as unknown (false positive rates). When comparing our results against neural networks (NN) with Monte Carlo dropout we found that BNNs generally outperform NNs. Finally, in our tests we did not find a single best choice as prior distribution. Instead, each dataset yielded the best results under a different prior, indicating that testing alternative options can improve the performance of BNNs.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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