asv.asreml {asreml}R Documentation

Approximate stratum variances

Description

Generic function to compute approximate stratum variances, degrees of freedom and coefficients for variance component models.

Usage

## S3 method for class 'asreml'
asv(object, order = c("as.is", "noeff"), vvp = FALSE, ...)

Arguments

object

An object of class asreml.

order

The sequence in which to consider the random terms. Options are "as.is" for the order as given in the asreml object, or "noeff" to be ordered by increasing number of effects, respectively. Note that the default ordering for random terms in asreml is "noeff" (default = "as.is").

vvp

If TRUE, the inverse of the average information matrix for the variance components (sigma scale) is returned (default = FALSE).

...

Any additional arguments.

Details

For linear mixed effects model, it is often possible to consider a natural ordering of the variance component parameters, including the residual. Based on an idea due to Thompson, 1980; here, asreml computes approximate stratum degrees of freedom and stratum variances by a modified Cholesky diagonalisation of the average information matrix.

Value

If vvp = FALSE, a rectangular matrix containing the degrees of freedom, approximate variances and the component coefficients for each random term is provided.

If vvp = TRUE, a list of length two containing the matrix of approximate stratum variances and the inverse average information matrix of the variance components in list components asv and vvp, respectively, is provided.

[Package asreml version 4.2.0.480 Index]