Automatic Determination of a Visit Sequence in mice
This function automatically determines a visit sequence for a specified
model in mice::mice
when passive variables are defined
as imputation methods. Note that redundant visits could be computed and
a user should check the plausibility of the result.
visitSequence.determine(impMethod, vis, data, maxit=10)
impMethod |
Vector with imputation methods |
vis |
Initial vector of visit sequence |
data |
Data frame to be used for multiple imputations |
maxit |
Maximum number of iteration for computation of the updated visit sequence |
Updated vector of the visit sequence
Used in the mice::mice
function as an argument.
The function mice::make.visitSequence
creates a visit sequence.
############################################################################# # EXAMPLE 1: Visit sequence for a small imputation model ############################################################################# data( data.smallscale ) # select a small number of variables dat <- data.smallscale[, paste0("v",1:4) ] V <- ncol(dat) # define initial vector of imputation methods impMethod <- rep("norm", V) names(impMethod) <- colnames(dat) # define variable names and imputation method for passive variables in a data frame dfr.impMeth <- data.frame( "variable"=NA, "impMethod"=NA ) dfr.impMeth[1,] <- c("v1_v1", "~ I(v1^2)" ) dfr.impMeth[2,] <- c("v2_v4", "~ I(v2*v4)" ) dfr.impMeth[3,] <- c("v4log", "~ I( log(abs(v4)))" ) dfr.impMeth[4,] <- c("v12", "~ I( v1 + v2 + 3*v1_v1 - v2_v4 )" ) # add variables to dataset and imputation methods VV <- nrow(dfr.impMeth) for (vv in 1:VV){ impMethod[ dfr.impMeth[vv,1] ] <- dfr.impMeth[vv,2] dat[, dfr.impMeth[vv,1] ] <- NA } # run empty imputation model to obtain initial vector of visit sequence imp0 <- mice::mice( dat, m=1, method=impMethod, maxit=0 ) imp0$vis # update visit sequence vis1 <- miceadds::visitSequence.determine( impMethod=impMethod, vis=imp0$vis, data=dat) # imputation with updated visit sequence imp <- mice::mice( dat, m=1, method=impMethod, visitSequence=vis1, maxit=2)
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