get_thresh: Get Thurstone thresholds

In scaleAlign: Scale Alignment for Between-Items Multidimensional Rasch Family Models

Description

Find Thurstone thresholds from a fitted model.

Usage

get_thresh(pars, itemtype, item_ind, alpha = 1)

Arguments

pars	Vector of estimated item parameters
itemtype	Item type: "1PL", "PCM", or "PCM2".
item_ind	Vector with one element for each parameter indicating which item each parameter is associated with.
alpha	Vector of item steepnesses, with one element for each item. Recycled if of length 1.

Value

Vector of Thurstone thresholds

Examples

if(require(TAM)){

set.seed(2524)

diff <- rnorm(10)

N <- 500

th <- rnorm(N)

probs <- 1 / (1 + exp(-outer(th, diff, "-")))

dat <- apply(probs, 2, function(p) as.numeric(p > runif(N)))

# fit the model

mod <- TAM::tam.mml(resp = dat, irtmodel = "1PL")

get_thresh(mod$xsi$xsi, itemtype = "1PL", item_ind = 1:10)

}

scaleAlign documentation built on Aug. 10, 2020, 9:07 a.m.