itemplotdata: Create list of data sets used in typical IRT plots

In CambridgeAssessmentResearch/unimirt: Applications of Unidimensional IRT using the R Package 'mirt'

Create list of data sets used in typical IRT plots

Description

For unidimensional IRT models this function creates a full set of the data that would be used in item information plots, item characteristic curves, and item category probability curves.

Usage

itemplotdata(mirtobj, which.items = NULL, Theta = NULL)

Arguments

mirtobj	An estimated IRT model (of class SingleGroupClass) estimated either using mirt or unimirt.
which.items	an integer vector indicating which items to include. By default all items are included.
Theta	a vector of ability values where calculations should focus. By default this is extracted from mirtobj.

Value

A list of data frames covering the required information at item level, test level and for individual item categories.

Examples

## Not run: 
mirt1=unimirt(mathsdata)
itemplotdata(mirt1,which.items=1:3,Theta=-2:2)

## End(Not run)

CambridgeAssessmentResearch/unimirt documentation built on June 10, 2025, 6:03 a.m.