HiGrad: Uncertainty Quantification for Online Learning and Stochastic Approximation

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Hauptverfasser: Su, Weijie J., Zhu, Yuancheng
Format: Preprint
Veröffentlicht: 2018
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author Su, Weijie J.
Zhu, Yuancheng
author_facet Su, Weijie J.
Zhu, Yuancheng
contents Stochastic gradient descent (SGD) is an immensely popular approach for online learning in settings where data arrives in a stream or data sizes are very large. However, despite an ever-increasing volume of work on SGD, much less is known about the statistical inferential properties of SGD-based predictions. Taking a fully inferential viewpoint, this paper introduces a novel procedure termed HiGrad to conduct statistical inference for online learning, without incurring additional computational cost compared with SGD. The HiGrad procedure begins by performing SGD updates for a while and then splits the single thread into several threads, and this procedure hierarchically operates in this fashion along each thread. With predictions provided by multiple threads in place, a $t$-based confidence interval is constructed by decorrelating predictions using covariance structures given by a Donsker-style extension of the Ruppert--Polyak averaging scheme, which is a technical contribution of independent interest. Under certain regularity conditions, the HiGrad confidence interval is shown to attain asymptotically exact coverage probability. Finally, the performance of HiGrad is evaluated through extensive simulation studies and a real data example. An R package \texttt{higrad} has been developed to implement the method.
format Preprint
id arxiv_https___arxiv_org_abs_1802_04876
institution arXiv
publishDate 2018
record_format arxiv
spellingShingle HiGrad: Uncertainty Quantification for Online Learning and Stochastic Approximation
Su, Weijie J.
Zhu, Yuancheng
Machine Learning
Distributed, Parallel, and Cluster Computing
Optimization and Control
Methodology
Stochastic gradient descent (SGD) is an immensely popular approach for online learning in settings where data arrives in a stream or data sizes are very large. However, despite an ever-increasing volume of work on SGD, much less is known about the statistical inferential properties of SGD-based predictions. Taking a fully inferential viewpoint, this paper introduces a novel procedure termed HiGrad to conduct statistical inference for online learning, without incurring additional computational cost compared with SGD. The HiGrad procedure begins by performing SGD updates for a while and then splits the single thread into several threads, and this procedure hierarchically operates in this fashion along each thread. With predictions provided by multiple threads in place, a $t$-based confidence interval is constructed by decorrelating predictions using covariance structures given by a Donsker-style extension of the Ruppert--Polyak averaging scheme, which is a technical contribution of independent interest. Under certain regularity conditions, the HiGrad confidence interval is shown to attain asymptotically exact coverage probability. Finally, the performance of HiGrad is evaluated through extensive simulation studies and a real data example. An R package \texttt{higrad} has been developed to implement the method.
title HiGrad: Uncertainty Quantification for Online Learning and Stochastic Approximation
topic Machine Learning
Distributed, Parallel, and Cluster Computing
Optimization and Control
Methodology
url https://arxiv.org/abs/1802.04876