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)
}