IIF3PLM: IIF for 3PLM

In exametrika: Test Theory Analysis and Biclustering

IIF for 3PLM

Description

Item Information Function for 3PLM

Usage

IIF3PLM(a, b, c, theta)

Arguments

a	slope parameter
b	location parameter
c	lower asymptote parameter
theta	ability parameter

Value

Returns a numeric vector representing the item information at each ability level theta. The information is calculated as: I(\theta) = \frac{a^2(1-P(\theta))(P(\theta)-c)^2}{(1-c)^2P(\theta)}

exametrika documentation built on Aug. 21, 2025, 5:27 p.m.