Returns a list defining the imputation strategies to be used to create the multivariate normal distribution parameters by merging those of the source group and reference group per patient.
Details
By default Jump to Reference (JR), Copy Reference (CR), Copy Increments in Reference (CIR), Last Mean Carried Forward (LMCF) and Missing at Random (MAR) are defined.
The user can define their own strategy functions (or overwrite the pre-defined ones)
by specifying a named input to the function i.e. NEW = function(...) ...
.
Only exception is MAR which cannot be overwritten.
All user defined functions must take 3 inputs: pars_group
, pars_ref
and
index_mar
. pars_group
and pars_ref
are both lists with elements mu
and sigma
representing the multivariate normal distribution parameters for
the subject's current group and reference group respectively. index_mar
will be
a logical vector specifying which visits the subject met the MAR assumption
at. The function must return a list with elements mu
and sigma
. See the implementation
of strategy_JR()
for an example.