tgp {irtoys} | R Documentation |
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.
tgp(choices, key, item, main = "Non-parametric response function", co = 1, label = FALSE)
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. |
Ivailo Partchev
James O. Ramsay (2000). TestGraf: A program for the graphical analysis of multiple choice test and questionnaire data. McGill University, Montreal, Canada
data(Unscored) key=c(2,3,1,1,4,1,2,1,2,3,3,4,3,4,2,2,4,3) tgp(choices=Unscored, key=key, item=4, co=NA, label=TRUE)