Specify or modify a Parameter Table in mirt

Specify or modify a parameter table in mirt.

Usage

mirt.specify.partable(mirt.partable, parlist, verbose=TRUE)

Arguments

mirt.partable

Parameter table in mirt package

parlist

List of parameters which are used for specification in the parameter table. See Examples.

verbose

An optional logical indicating whether the some warnings should be printed.

Value

A modified parameter table

Author

Alexander Robitzsch, Phil Chalmers

Examples

#############################################################################
# EXAMPLE 1: Modifying a parameter table for single group
#############################################################################

library(mirt)
data(LSAT7,package="mirt")
data <- mirt::expand.table(LSAT7)

mirt.partable <- mirt::mirt(data, 1, pars="values")
colnames(mirt.partable)
## > colnames(mirt.partable) [1] 'group' 'item' 'class' 'name' 'parnum' 'value'
##   'lbound' 'ubound' 'est' 'prior.type' 'prior_1' 'prior_2'

# specify some values of item parameters
value <- data.frame(d=c(0.7, -1, NA), a1=c(1, 1.2, 1.3), g=c(NA, 0.25, 0.25))
rownames(value) <- c("Item.1", "Item.4", "Item.3")

# fix some item paramters
est1 <- data.frame(d=c(TRUE, NA), a1=c(FALSE, TRUE))
rownames(est1) <- c("Item.4", "Item.3")

# estimate all guessing parameters
est2 <- data.frame(g=rep(TRUE, 5))
rownames(est2) <- colnames(data)

# prior distributions
prior.type <- data.frame(g=rep("norm", 4))
rownames(prior.type) <- c("Item.1", "Item.2", "Item.4", "Item.5")
prior_1 <- data.frame(g=rep(-1.38, 4))
rownames(prior_1) <- c("Item.1", "Item.2", "Item.4", "Item.5")
prior_2 <- data.frame(g=rep(0.5, 4))
rownames(prior_2) <- c("Item.1", "Item.2", "Item.4", "Item.5")

# misspecify some entries
rownames(prior_2)[c(3,2)] <- c("A", "B")
rownames(est1)[2] <- c("B")

# define complete list with parameter specification
parlist <- list(value=value, est=est1, est=est2, prior.type=prior.type,
      prior_1=prior_1, prior_2=prior_2)

# modify parameter table
mirt.specify.partable(mirt.partable, parlist)