IIF3PLM {exametrika} | R Documentation |
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)}
[Package exametrika version 1.1.0 Index]