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HDShOP (version 0.1.5)

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.

Y_0

a numeric variable. Shrinkage target coefficient.

References

Examples

Run this code
n<-7e2 # number of realizations
p<-.5*n # number of assets
x <- matrix(data = rnorm(n*p), nrow = p, ncol = n)
mm <- mean_js(x=x, Y_0 = 1)

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