plot.iif: A plot method for item information functions
In lebebr01/irtoys-2: Simple interface to the estimation and plotting of IRT models

Description Usage Arguments Author(s) See Also Examples

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

  ## S3 method for class 'iif'
 plot(x, add = FALSE,
    main = "Item information function", co = 1,
    label = FALSE, ...)

`x`	An object produced by function `iif`
`add`	When `add=T`, the IIF 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 IIF curve. Default is 1 for black. Use `co=NA` to plot each IIF in a different colour.
`label`	When `label=T`, individual curves will be labeled with the item number.
`...`	Any additional plotting parameters

Ivailo Partchev

iif

# plot IIF for all items in red, label with item number
plot(iif(Scored2pl$est), co="red", label=TRUE)
# plot IIF for items 2, 3, and 7 in different colours
plot(iif(Scored2pl$est[c(2,3,7),]), co=NA)