Item Response Function for the 3PL Model

Computes the item response function for the 3PL model in the TAM package.

tam_irf_3pl(theta, AXsi, B, guess=NULL, subtract_max=TRUE)

Arguments

theta	Matrix or vector of \(\bold{\theta}\) values
AXsi	Matrix of item-category parameters
B	Array containing item-category loadings
guess	Optional parameter of guessing parameters
subtract_max	Logical indicating whether numerical underflow in probabilities should be explicitly avoided

Value

Array containing item response probabilities arranged by the dimensions theta points \(\times\) items \(\times\) categories

Examples

if (FALSE) {
#############################################################################
# EXAMPLE 1: 2PL example
#############################################################################

library(sirt)
data(data.read, package="sirt")
dat <- data.read

#* estimate 2PL model
mod <- TAM::tam.mml.2pl( resp=dat )
#* define theta vector
theta <- seq(-3,3, len=41)
#* compute item response probabilities
probs <- TAM::tam_irf_3pl( theta=theta, AXsi=mod$AXsi, B=mod$B )
str(probs)
}