QA238 : Shrinkage estimator for the highdimensional multivariate normal covarianc matrix
Thesis > Central Library of Shahrood University > Mathematical Sciences > MSc > 2014
Authors:
Elham Ashoori [Author], Mohammad Arashi[Supervisor]
Abstarct: Many applications require an estimate for the covariance matrix that is non-singular and well-conditioned. As the dimensionality increases, the sample covariance matrix becomes ill-conditioned or even singular. A common approach to estimating the covariance matrix when the dimensionality is large is that of Stein-type shrinkage estimation. A convex combination of the sample covariance matrix and a wellconditioned target matrix is used to estimate the covariance matrix. Recent work in the literature has shown that an optimal combination exists under mean-squared loss, however it must be estimated from the data. we introduce a new set of estimators for the optimal convex combination for three commonly used target matrices. A simulation study shows an improvement over those in the literature in cases of extreme high-dimensionality of the data. A data analysis shows the estimators are effective in a discriminant and classification analysis.
Keywords:
#Covariance matrix #Shrinkage estimation #High-dimensional data analysis Link
Keeping place: Central Library of Shahrood University
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