This paper proposes a novel shrinkage estimator for high-dimensional covariance matrices by extending the Oracle Approximating Shrinkage (OAS) of Chen et al. (2009) to target the diagonal elements of ...

A procedure is presented for rapidly computing the diagnonal elements of a large numerator relationship matrix, say $\mathbf {A}$. It also generates a lower triangular matrix, say $\mathbf {L}$, ...