mean_js: James-Stein shrinkage estimator of the mean vector
Description
James-Stein shrinkage estimator of the mean vector as suggested in
Jorion1986;textualHDShOP. The estimator is given by
$$\hat \mu_{JS} = (1-\beta) \bar x + \beta Y_0 1,$$
where \(\bar x\) is the sample mean vector, \(\beta\) is the shrinkage
coefficient which minimizes a quadratic loss given by Eq.(11) in
Jorion1986;textualHDShOP.
\(Y_0\) is a prespecified value.
Usage
mean_js(x, Y_0 = 1)
Value
a numeric vector containing the James-Stein shrinkage estimator
of the mean vector.
Arguments
x
a p by n matrix or a data frame of asset returns. Rows represent
different assets, columns -- observations.