irtoys: tgf – R documentation

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tgf

Non-parametric option curves

Description

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.

Usage

tgf(choices, key, item, main = "Non-parametric response function", co = 1,
  label = FALSE)

Arguments

`choices`	A matrix of responses to multiple-choice items: persons as rows, items as columns. As a rare exception in `irtoys`, responses must not be recoded to 0/1, and there may be missing responses.
`key`	A vector containing the key (correct answers) to the items in `choices`.
`item`	A single number pointing to the item (column of `choices`) to plot.
`main`	The main title of the plot, given that `add=F`.
`co`	The colour of the curves. Default is 1 for black. Use `co=NA` to plot each curve in a different colour.
`label`	When `label=T`, individual curves will be labeled with the item number.

Author(s)

Ivailo Partchev

References

James O. Ramsay (2000). TestGraf: A program for the graphical analysis of multiple choice test and questionnaire data. McGill University, Montreal, Canada

Examples

key=c(2,3,1,1,4,1,2,1,2,3,3,4,3,4,2,2,4,3)
tgf(choices=Unscored, key=key, item=4, co=NA, label=TRUE)

irtoys

A Collection of Functions Related to Item Response Theory (IRT)

v0.2.1

GPL (>= 2)

Authors

Ivailo Partchev [aut, cre], Gunter Maris [aut], Tamaki Hattori [ctb]

Initial release

2017-12-15

tgf