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)
}