strategies {rbmi} | R Documentation |
Strategies
Description
These functions are used to implement various reference based imputation strategies by combining a subjects own distribution with that of a reference distribution based upon which of their visits failed to meet the Missing-at-Random (MAR) assumption.
Usage
strategy_MAR(pars_group, pars_ref, index_mar)
strategy_JR(pars_group, pars_ref, index_mar)
strategy_CR(pars_group, pars_ref, index_mar)
strategy_CIR(pars_group, pars_ref, index_mar)
strategy_LMCF(pars_group, pars_ref, index_mar)
Arguments
pars_group |
A list of parameters for the subject's group. See details. |
pars_ref |
A list of parameters for the subject's reference group. See details. |
index_mar |
A logical vector indicating which visits meet the MAR assumption for the subject. I.e. this identifies the observations after a non-MAR intercurrent event (ICE). |
Details
pars_group
and pars_ref
both must be a list containing elements mu
and sigma
.
mu
must be a numeric vector and sigma
must be a square matrix symmetric covariance
matrix with dimensions equal to the length of mu
and index_mar
. e.g.
list( mu = c(1,2,3), sigma = matrix(c(4,3,2,3,5,4,2,4,6), nrow = 3, ncol = 3) )
Users can define their own strategy functions and include them via the strategies
argument to impute()
using getStrategies()
. That being said the following
strategies are available "out the box":
Missing at Random (MAR)
Jump to Reference (JR)
Copy Reference (CR)
Copy Increments in Reference (CIR)
Last Mean Carried Forward (LMCF)