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A Note on Choosing the Threshold for Large Covariance Estimations in Factor Models
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A Note on Choosing the Threshold for Large Covariance Estimations in Factor Models

Yuan Liao
ArXiv.org
Cornell University
08/30/2016
DOI: 10.48550/arxiv.1608.08318
url
https://doi.org/10.48550/arxiv.1608.08318View
Preprint (Author's original)This preprint has not been evaluated by subject experts through peer review. Preprints may undergo extensive changes and/or become peer-reviewed journal articles. Open Access

Abstract

This note shows that for i.i.d. data, estimating large covariance matrices in factor models can be casted using a simple plug-in method to choose the threshold: μjl = c0 √n Φ−1(1 – α 2p2 ) √ √ √ √ 1 n n∑ i=1̂ u2 jî u2 li. This is motivated by the tuning parameter suggested by Belloni et al. (2012) in the lasso literature. It also leads to the minimax rate of convergence of the large covariance matrix estimator. Previously, the minimaxity is achievable only when n = o(p log p) by Fan et al. (2013), and now this condition is weakened to n = o(p2 log p). Here n denotes the sample size and p denotes the dimension.
Statistics - Methodology

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