randcov_initial: Create a random effects covariance parameter initial object
Description
Create a random effects (co)variance parameter initial object that specifies
initial and/or known values to use while estimating random effect variances
with modeling functions.
Usage
randcov_initial(..., known)
Value
A list with two elements: initial and is_known.
initial is a named numeric vector indicating the random effect variances
with specified initial and/or known values. is_known is a named
logical vector indicating whether the random effect variances in
initial are known or not.
Arguments
...
Arguments to randcov_params().
known
A character vector indicating which random effect variances are to be
assumed known. The value "given" is shorthand for assuming all
random effect variances given to randcov_initial() are assumed known.
Details
A random effect is specified as \(Zu\), where \(Z\) is the random
effects design matrix and u is the random effect. The covariance of
\(Zu\) is \(\sigma 2 ZZ^T\), where \(\sigma 2\) is the random effect
variance, and \(Z^T\) is the transpose of \(Z\).