mmrm 0.2.2
New Features
- Add support for Kenward-Roger adjusted coefficients covariance
matrix and degrees of freedom in
mmrm
function call with
argument method
. Options are “Kenward-Roger”,
“Kenward-Roger-Linear” and “Satterthwaite” (which is still the default).
Subsequent methods calls will respect this initial choice,
e.g. vcov(fit)
will return the adjusted coefficients
covariance matrix if a Kenward-Roger method has been used.
- Update the
mmrm
arguments to allow users more
fine-grained control, e.g.
mmrm(..., start = start, optimizer = c("BFGS", "nlminb"))
to set the starting values for the variance estimates and to choose the
available optimizers. These arguments will be passed to the new function
mmrm_control
.
- Add new argument
drop_visit_levels
to allow users to
keep all levels in visits, even when they are not observed in the data.
Dropping unobserved levels was done silently previously, and now a
message will be given. See ?mmrm_control
for more
details.
Bug Fixes
- Previously duplicate time points could be present for a single
subject, and this could lead to segmentation faults if more than the
total number of unique time points were available for any subject. Now
it is checked that there are no duplicate time points per subject, and
this is explained also in the function documentation and the
introduction vignette.
- Previously in
mmrm
calls, the weights
object in the environment where the formula is defined was replaced by
the weights
used internally. Now this behavior is removed
and your variable weights
e.g. in the global environment
will no longer be replaced.
Miscellaneous
- Deprecated
free_cores()
in favor of
parallelly::availableCores(omit = 1)
.
- Deprecated
optimizer = "automatic"
in favor of not
specifying the optimizer
. By default, all remaining
optimizers will be tried if the first optimizer fails to reach
convergence.
mmrm 0.1.5
- First CRAN version of the package.
- The package fits mixed models for repeated measures (MMRM) based on
the marginal linear model without random effects.
- The motivation for this package is to have a fast, reliable (in
terms of convergence behavior) and feature complete implementation of
MMRM in R.
New Features
- Currently 10 covariance structures are supported (unstructured; as
well as homogeneous and heterogeneous versions of Toeplitz,
auto-regressive order one, ante-dependence, compound symmetry; and
spatial exponential).
- Fast C++ implementation of Maximum Likelihood (ML) and Restricted
Maximum Likelihood (REML) estimation.
- Currently Satterthwaite adjusted degrees of freedom calculation is
supported.
- Interface to the
emmeans
package for computing
estimated marginal means (also called least-square means) for the
coefficients.
- Multiple optimizers are run to reach convergence in as many cases as
possible.
- Flexible formula based model specification and support for standard
S3 methods such as
summary
, logLik
, etc.