ItemInformationFunc {exametrika}R Documentation

IIF for 4PLM

Description

Item Information Function for 4PLM

Usage

ItemInformationFunc(a = 1, b, c = 0, d = 1, theta)

Arguments

a

slope parameter

b

location parameter

c

lower asymptote parameter

d

upper asymptote parameter

theta

ability parameter

Value

Returns a numeric vector representing the item information at each ability level theta. The information is calculated based on the first derivative of the log-likelihood of the 4PL model with respect to theta.


[Package exametrika version 1.5.1 Index]