Test_info: Plot test information function
In seonghobae/flirt.x32: Flexible Item Response Theory Modeling

Description Usage Arguments Author(s) See Also Examples

A function to plot test information function for unidimensional 1PL, 2PL, and 3PL models

1 2	## S3 method for class 'flirt' Test_info(alpha=NULL, beta, guess=NULL , inside=NULL, ylim=NULL)

`alpha`	α_i parameter estimates. If `NULL`, α_i=1
`beta`	β_i parameter estimates
`guess`	c_i (guessing) parameter estimates. If `NULL`, c_i=0
`inside`	If `TRUE`, I (θ) = ∑_i^I [α_i^2 \times \frac{(P_i - c_i)}{(1-c_i)^2} \times \frac{(1-P_i)}{P_i}] is computed
`ylim`	the y limits of the plot.

Minjeong Jeon <jeon.117@osu.edu>

flirt

library(flirt)

## verbal aggression data

data(verb2)

# 2-dimensional 2PL model  for binary data:  a(th+b) parameterization
result2 <- flirt(data=verb2, loading=list(on=T, inside=T), control=list(nq=5) )
alpha <- result2@pars[1:24,2]
beta <- result2@pars[25:48,1]

# test information function 
Test_info(beta= beta)