Fits a MMRM model allowing for different covariance structures using mmrm::mmrm()
.
Returns a list
of key model parameters beta
, sigma
and an additional element failed
indicating whether or not the fit failed to converge. If the fit did fail to converge
beta
and sigma
will not be present.
Usage
fit_mmrm(
designmat,
outcome,
subjid,
visit,
group,
cov_struct = c("us", "ad", "adh", "ar1", "ar1h", "cs", "csh", "toep", "toeph"),
REML = TRUE,
same_cov = TRUE
)
Arguments
- designmat
a
data.frame
ormatrix
containing the covariates to use in the MMRM model. Dummy variables must already be expanded out, i.e. viastats::model.matrix()
. Cannot contain any missing values- outcome
a numeric vector. The outcome value to be regressed on in the MMRM model.
- subjid
a character / factor vector. The subject identifier used to link separate visits that belong to the same subject.
- visit
a character / factor vector. Indicates which visit the outcome value occurred on.
- group
a character / factor vector. Indicates which treatment group the patient belongs to.
- cov_struct
a character value. Specifies which covariance structure to use. Must be one of
"us"
(default),"ad"
,"adh"
,"ar1"
,"ar1h"
,"cs"
,"csh"
,"toep"
, or"toeph"
)- REML
logical. Specifies whether restricted maximum likelihood should be used
- same_cov
logical. Used to specify if a shared or individual covariance matrix should be used per
group