plot.irf: A plot method for item response 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 response functions. The x argument of irf should better be left out unless something special is required.

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

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

Ivailo Partchev

irf

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