SlopePlot: Compare slope parameters across items

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

Compare slope parameters across items

Description

This function shows the slope parameters graphically with each of them compared against a dotted reference line relating to the median parameter value within the model. If the model was estimated with "SE=TRUE" then 95 per cent confidence intervals for the slope parameters are displayed within the chart.

Usage

SlopePlot(mirtobj, which.items = 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 in the plot. By default all items are included. Note that the reference median line is always based on all items in the object.

Value

A ggplot.

Examples

## Not run: 
mirt1=unimirt(mathsdata,"gpcm",SE=TRUE)
SlopePlot(mirt1)
SlopePlot(mirt1,1:10)#plot for first 10 items only

## End(Not run)

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