Skip to contents

Item Information Function for GRM

Source: R/14_grm.R
grm_iif.Rd

Calculates the value of the Item Information Function for the Graded Response Model.

Usage

grm_iif(theta, a, b)

Arguments

theta

Latent trait value of the subject

a

Discrimination parameter of IRF

b

Vector of difficulty parameters (thresholds) of IRF

Value

Value of the Item Information Function

Examples

if (FALSE) { # \dontrun{
# Example for an item with 3 categories
a <- 1.5
b <- c(-1.0, 1.0)
thetas <- seq(-3, 3, by = 0.1)
info <- sapply(thetas, function(t) grm_iif(t, a, b))
plot(thetas, info, type = "l", xlab = "Theta", ylab = "Information")
} # }