The model frame is produced by mixmeta
when fitting the meta-analytical model, and stored in the mixmeta
object if argument model=TRUE
. Alternatively, the model frame is directly returned from a call to mixmeta
with argument method="model.frame"
. The method function model.frame
simply extracts the saved model frame if available, or otherwise evaluates a call to mixmeta
when method="model.frame"
.
The method function model.matrix
extracts the design matrix for the fixed-effects part of a fitted meta-analytical model. It first extract the model frame by calling model.frame
, and then passes the call to the default method.
Note that the model frame of mixmeta
models consist of terms for both the fixed and random-effects parts, the latter including also the grouping factors. This information can be used to reconstruct the proper model frame or matrix for each part.
These methods functions are similar to those provided for regression objects lm
and lm
.