This function has default values for most of the arguments, some of them set internally. Non-default values are passed through the control argument of mixmeta
. Many arguments refer to specific fitting procedures. See the help page of the related estimator for details.
The function automatically sets non-default values for some control arguments for optim
, unless explicitly set in the list passed to it. Specifically, the function selects fnscale=-1
, maxit=maxiter
and reltol=reltol
, where the latter two are specified by other arguments of this function.
The arguments initPsi
and Psifix
are used to provide information for estimation procedures of the random-effects parameters in likelihood-based methods. Specifically, the former is used to choose non-default starting values (see mixmeta.ml
), and the latter for defining the fixed (known) part of specific (co)variance structures
. In multilevel models, these arguments must be lists with named components referring to one or more levels of grouping defined by the argument random
of mixmeta
.
The argument addSlist
can be used to define more complex (known) error structures of the outcome(s) that are usually provided through the argument S
of mixmeta
as within-unit variances (or (co)variance matrices for multivariate models). This can be useful when these error structures spans multiple units (rows), and the between-unit correlation cannot be defined through S
, for instance in dose-response meta-analysis (see examples in mixmeta
). Note that this information is passed internally after the data have be re-ordered following the grouping defined by random
in mixmeta
, and this should be consistent in addSlist
. Specifically, the grouping variables are assumed as factors and therefore the groups are taken in alphabetical/numeric order. It is suggested to re-order the data according to this order of the groups before fitting the model, so to ensure consistency between the grouped data and addSlist
.