randcov_initial function

Create a random effects covariance parameter initial object

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.

randcov_initial(..., known)

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.

Returns

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.

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 $Z$.

Examples

randcov_initial(group = 1)
randcov_initial(group = 1, known = "group")