R: Functions of variance components

vpredict {asreml} | R Documentation

## Functions of variance components

### Description

Calculates means and approximated standard errors from functions of variance components from an `asreml` object.

### Usage

    vpredict(object, xform, ...)

### Arguments

`object` | An `asreml` object.
`xform` | A two-sided formula, where the left-hand side labels the function name. The right-hand side defines the function to calculate as an algebraic expression.

### Details

The standard error of the computed value is approximated using the Delta method with the function `deriv()`, which calculates algebraic derivatives for a wide range of expressions. Any of the variance components to be included in the function are represented as: `"V1"`, `"V2"`, `"V3"`, ... in the order they appear in `object$vparameters`. Parentheses, and simple functions like `log`, `exp`, `sqrt` are also allowed. Results are always presented in sigma scale.

### Value

A single-row data frame with components:

- `Estimate`: The estimated value of the algebraic expression.

- `SE`: The estimated approximated standard error.

[Package asreml version 4.2.0.480 Index]