psychotree (version 0.11-1)

node_raschplot: Panel-Generating Function for Visualizing Rasch Tree Models

Description

Panel-generating function for visualizing the item parameters from the nodes in Rasch tree models. For convenience, a base graphics function for Rasch models is provided.

Usage

node_raschplot(mobobj, id = TRUE, difficulty = TRUE,
  center = TRUE, index = TRUE, names = NULL, abbreviate = FALSE, ref = TRUE,
  col = cbind("lightgray", "black"), refcol = "lightgray", linecol = "black",
  lty = 2, cex = 0.5, pch = cbind(19, 1), xscale = NULL, yscale = NULL,
  xaxis = TRUE, yaxis = TRUE, ylines = 1.5)
## S3 method for class 'RaschModel':
plot(x, difficulty = TRUE,
  center = TRUE, index = TRUE, names = NULL, abbreviate = FALSE, ref = TRUE,
  col = cbind("lightgray", "black"), refcol = "lightgray", linecol = "black", lty = 2,
  cex = 1, pch = cbind(19, 1), type = NULL, ylim = NULL, xlab = "Items", ylab = NULL, ...)

Arguments

mobobj

an object of class "mob" based on Rasch models fitted by RaschModel.

id

logical. Should the node ID be displayed?

difficulty

logical. Should item difficulty (or alternatively: easiness) parameters be displayed?

center

logical. Should the item parameters be centered?

index

logical. Should different indexes for different items be used?

names

logical. Should the names for the objects be displayed?

abbreviate

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

ref

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

col, pch, cex

graphical appearance of plotting symbols. Can be of the same length as number of items. Additionally col and pch can be matrices with two columns resulting in two symbols being overplotted.

refcol

line color for reference line (if ref).

linecol

line color.

lty

line type.

xscale, yscale

x and y axis limits.

xaxis, yaxis

logical. Should a axes be plotted?

ylines

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

x

an object of class "RaschModel".

type

plot type. Default is "b" if index is TRUE.

ylim

y axis limits.

xlab, ylab

x and y axis labels.

...

further arguments passed to plot.

Value

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

Details

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

See Also

raschtree