svc.asreml | R Documentation

## Stratum Variance Components

### Description

A method to compute the approximate stratum variances for simple variance component models.

### Usage

    svc.asreml(object, order = "user")

### Arguments

`object` | an object of class `asreml`
`order` | the sequence in which to consider the random terms: may be one of "user", "R" or "noef" for the order as specified in the `random` model formula, the order as determined by `terms(random,keep.order=FALSE)` or ordered by increasing number of effects, respectively.

### Details

Approximate stratum variances and degrees of freedom for simple variance components models are returned. For the 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), `asreml` computes approximate stratum degrees of freedom and stratum variances by a modified Cholesky diagonalisation of the average information matrix.

### Value

A matrix of approximate stratum variances, degrees of freedom and component coefficients.

### Author(s)

David Butler

### References

Thompson, R. (1980). Maximum likelihood estimation of variance components, Math. Operationsforsch Statistics, 11, 545-561.

### See Also

`asreml` `wald.asreml`

### Examples

    data(oats, package="asreml3")
    oats.asr <- asreml(yield ~ Variety*Nitrogen,
                       random = ~ Blocks/Wplots, data=oats)
    svc(oats.asr)