Outlier-Robust Sparse Mean Estimation for Heavy-Tailed Distributions
- URL: http://arxiv.org/abs/2211.16333v1
- Date: Tue, 29 Nov 2022 16:13:50 GMT
- Title: Outlier-Robust Sparse Mean Estimation for Heavy-Tailed Distributions
- Authors: Ilias Diakonikolas, Daniel M. Kane, Jasper C.H. Lee, Ankit Pensia
- Abstract summary: Given a small number of corrupted samples, the goal is to efficiently compute a hypothesis that accurately approximates $mu$ with high probability.
Our algorithm achieves the optimal error using a number of samples scaling logarithmically with the ambient dimension.
Our analysis may be of independent interest, involving the delicate design of a (non-spectral) decomposition for positive semi-definite satisfying certain sparsity properties.
- Score: 42.6763105645717
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: We study the fundamental task of outlier-robust mean estimation for
heavy-tailed distributions in the presence of sparsity. Specifically, given a
small number of corrupted samples from a high-dimensional heavy-tailed
distribution whose mean $\mu$ is guaranteed to be sparse, the goal is to
efficiently compute a hypothesis that accurately approximates $\mu$ with high
probability. Prior work had obtained efficient algorithms for robust sparse
mean estimation of light-tailed distributions. In this work, we give the first
sample-efficient and polynomial-time robust sparse mean estimator for
heavy-tailed distributions under mild moment assumptions. Our algorithm
achieves the optimal asymptotic error using a number of samples scaling
logarithmically with the ambient dimension. Importantly, the sample complexity
of our method is optimal as a function of the failure probability $\tau$,
having an additive $\log(1/\tau)$ dependence. Our algorithm leverages the
stability-based approach from the algorithmic robust statistics literature,
with crucial (and necessary) adaptations required in our setting. Our analysis
may be of independent interest, involving the delicate design of a
(non-spectral) decomposition for positive semi-definite matrices satisfying
certain sparsity properties.
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