Eigenvectors of some large sample covariance matrix ensembles |
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Authors: | Olivier Ledoit Sandrine P��ch�� |
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Institution: | 1. Institute for Empirical Research in Economics, University of Zurich, Bl??mlisalpstrasse 10, 8006, Zurich, Switzerland 2. Institut Fourier, Universit?? Grenoble 1, 100 rue des Maths, BP 74, 38402, Saint-Martin-d??H??res, France
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Abstract: | We consider sample covariance matrices ${S_N=\frac{1}{p}\Sigma_N^{1/2}X_NX_N^* \Sigma_N^{1/2}}$ where X N is a N ×? p real or complex matrix with i.i.d. entries with finite 12th moment and ?? N is a N ×? N positive definite matrix. In addition we assume that the spectral measure of ?? N almost surely converges to some limiting probability distribution as N ?? ?? and p/N ?? ?? >?0. We quantify the relationship between sample and population eigenvectors by studying the asymptotics of functionals of the type ${\frac{1}{N}\text{Tr} ( g(\Sigma_N) (S_N-zI)^{-1}),}$ where I is the identity matrix, g is a bounded function and z is a complex number. This is then used to compute the asymptotically optimal bias correction for sample eigenvalues, paving the way for a new generation of improved estimators of the covariance matrix and its inverse. |
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