mirt (version 1.3)

read.mirt: Translate mirt parameters for plink package

Description

This function exports item parameters from the mirt package to the plink package.

Usage

read.mirt(x, as.irt.pars = TRUE, ...)

Arguments

x

an object returned from mirt, bfactor, or multipleGroup

as.irt.pars

if TRUE, the parameters will be output as an irt.pars object

...

additional arguments to be passed to coef()

Examples

## unidimensional

data <- expand.table(LSAT7)
(mod1 <- mirt(data, 1))
plinkpars <- read.mirt(mod1)
plot(plinkpars)
itemplot(mod1, 1)

#graded
mod2 <- mirt(Science, 1)
plinkpars <- read.mirt(mod2)
plot(plinkpars)
itemplot(mod2, 1)

#gpcm
mod3 <- mirt(Science, 1, itemtype = 'gpcm')
plinkpars <- read.mirt(mod3)
plot(plinkpars)
itemplot(mod3, 1)

#nominal
mod4 <- mirt(Science, 1, itemtype = 'nominal')
plinkpars <- read.mirt(mod4)
plot(plinkpars)
itemplot(mod4, 1)

## multidimensional

data <- expand.table(LSAT7)
(mod1 <- mirt(data, 2))
plinkpars <- read.mirt(mod1)
plot(plinkpars)
itemplot(mod1, 1)

cmod <- mirt.model('
   F1 = 1,4,5
   F2 = 2-4')
model <- mirt(data, cmod)
plot(read.mirt(model))
itemplot(model, 1)

#graded
mod2 <- mirt(Science, 2)
plinkpars <- read.mirt(mod2)
plot(plinkpars)
itemplot(mod2, 1)

### multiple group
set.seed(1234)
dat <- expand.table(LSAT7)
group <- sample(c('g1', 'g2'), nrow(dat), TRUE)
mod <- multipleGroup(dat, 1, group)

# convert, and combine pars
plinkMG <- read.mirt(mod)
combine <- matrix(1:5, 5, 2)
comb <- combine.pars(plinkMG, combine, grp.names=unique(group))
out <- plink(comb, rescale="SL")
equate(out)
equate(out, method = 'OSE')