Panel-Generating Function for Visualizing IRT Tree Models

Description

Panel-generating function for visualizing the parameters from the nodes in Rasch, rating scale or partial credit tree models.

Usage

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node_profileplot(mobobj, what = c("items", "thresholds", "discriminations"),
  parg = list(type = NULL, ref = NULL, alias = TRUE), id = TRUE,
  names = FALSE, abbreviate = TRUE, index = TRUE, ref = TRUE, col = "black",
  border = col, linecol = "black", refcol = "lightgray", cex = 0.5, pch = 21,
  xscale = NULL, yscale = NULL, ylines = 2, ...)

Arguments

mobobj

an object of class "mob" based on rasch models fitted by raschmodel, rating scale models fitted by rsmodel or partial credit models fitted by pcmodel.

what

character, specifying the type of parameters to be plotted.

parg

list of arguments passed over to internal calls of itempar, threshpar or discrpar.

id

logical. Should the node ID be displayed?

names

logical or character. If TRUE, the names of the items are displayed on the x-axis. If FALSE, numbers of items are shown. Alternatively a character vector of the same length as the number of items can be supplied.

abbreviate

logical. Should item names be abbreviated? If numeric this controls the length of the abbreviation.

index

logical. Should different indexes for different items be used?

ref

logical. Should a horizontal line for the reference level be drawn?

col, border, pch, cex

graphical appearance of plotting symbols.

linecol, refcol

character, specifying the line color to use for the profile lines and reference line, respectively.

xscale, yscale

x and y axis limits.

ylines

numeric. Number of lines used for y-axis labels.

...

further arguments currently not used.

Details

The panel-generating function node_profileplot is called by the plot method for "raschtree" objects and does not have to be called by the user directly.

Prior to version 0.13-1, node_profileplot was called node_raschplot.

Value

A panel function which can be supplied to the plot method for "mob" objects.

See Also

raschtree