irtoys (version 0.1.2)

plot.tif: A plot method for test information functions

Description

Useful for plotting test information functions. The x argument of tif should better be left out unless something special is required.

Usage

## S3 method for class 'tif':
plot(x, add = FALSE, main = "Test information function", co = 1, ...)

Arguments

x

An object produced by function tif

add

When add=T, the TIF is added to a plot, otherwise a new plot is started. Default is F.

main

The main title of the plot, given that add=F.

co

The colour of the TIF curve. Default is 1 for black. Use co=NA to plot each TIF in a different colour.

...

Any additional plotting parameters

See Also

tif

Examples

data(Scored)
p.2pl  <- est(Scored, model="2PL", engine="ltm")
plot(tif(p.2pl))