mirt (version 1.6.1)

imputeMissing: Imputing plausible data for missing values

Description

Given an estimated model from any of mirt's model fitting functions and an estimate of the latent trait, impute plausible missing data values. Returns the original data in a data.frame without any NA values.

Usage

imputeMissing(x, Theta, ...)

Arguments

x

an estimated model x from the mirt package

Theta

a matrix containing the estimates of the latent trait scores (e.g., via fscores)

...

additional arguments to pass

Examples

dat <- expand.table(LSAT7)
(original <- mirt(dat, 1))
NAperson <- sample(1:nrow(dat), 20, replace = TRUE)
NAitem <- sample(1:ncol(dat), 20, replace = TRUE)
for(i in 1:20)
    dat[NAperson[i], NAitem[i]] <- NA
(mod <- mirt(dat, 1))
scores <- fscores(mod, method = 'MAP', scores.only = TRUE)

#re-estimate imputed dataset (good to do this multiple times and average over)
fulldata <- imputeMissing(mod, scores)
(fullmod <- mirt(fulldata, 1))

#with multipleGroup
group <- rep(c('group1', 'group2'), each=500)
mod2 <- multipleGroup(dat, 1, group)
fs <- fscores(mod2, full.scores=TRUE)
fulldata2 <- imputeMissing(mod2, fs)