plot.trf

An object produced by function <code>trf</code>

When <code>add=T</code>, the IRF is added to a plot, otherwise a new
plot is started. Default is F.

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

main

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

Any additional plotting parameters

Useful for plotting test response functions. The <code>x</code> argument of
<code>trf</code> should better be left out unless something special is required.

models

A collection of functions useful in learning and practicing IRT,
which can be combined into larger programs. Provides basic CTT analysis,
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), ability estimation (MLE, BME, EAP, WLE, plausible
values), item and person fit statistics, scaling methods (MM, MS, Stocking-Lord,
and the complete Hebaera method), and a rich array of parametric and
non-parametric (kernel) plots. Estimates and plots Haberman's interaction model
when all items are dichotomously scored.

plot.trf: A plot method for test response functions

Description

Usage

Arguments

See Also

Examples