A matrix of responses to multiple-choice
  items: persons as rows, items as columns. As a rare
  exception in <code>irtoys</code>, responses must not be recoded
  to 0/1, and there may be missing responses.

choices

A vector containing the key (correct answers)
  to the items in <code>choices</code>.

A single number pointing to the item (column
  of <code>choices</code>) to plot.

item

The main title of the plot, given that
  <code>add=F</code>.

main

The colour of the curves. Default is 1 for
  black. Use <code>co=NA</code> to plot each curve in a different
  colour.

When <code>label=T</code>, individual curves will
  be labeled with the item number.

label

A plotting function producing non-parametric analogues of
  the IRF for each option in a multiple choice item not
  unlike those in Jim Ramsay's TestGraf program.

models

Provides a simple common interface to the estimation of
        item parameters in IRT models for binary responses with three
        different programs (ICL, BILOG-MG, and ltm, and a variety of
        functions useful with IRT models.

tgp: Non-parametric option curves

Description

Usage

Arguments

References

See Also

Examples