Panel-generating function for visualizing the regions of expected item responses across abilities (via shaded rectangles) based on the parameters from the nodes in IRT tree models.
node_regionplot(
mobobj,
names = FALSE,
abbreviate = TRUE,
type = c("mode", "median", "mean"),
ref = NULL,
ylim = NULL,
off = 0.1,
col_fun = gray.colors,
bg = "white",
uo_show = TRUE,
uo_col = "red",
uo_lty = 2,
uo_lwd = 1.25,
ylines = 2
)A panel function which can be supplied to the plot method for "npltree" objects
or "mob" objects fitted by npltree.
an object of class "npltree" or class "mob"
fitted by npltree
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.
logical. Should item names be abbreviated? If numeric this controls the length of the abbreviation.
character, specifying which type of threshold parameters
are to be used to mark the category regions per item in the plot
(see regionplot for details).
a vector of labels or position indices of item parameters
which should be used as restriction/for normalization.
If NULL (the default), all items are used (sum zero restriction).
See threshpar for more details.
y axis limits
numeric, the distance (in scale units) between two item rectangles.
function. Function to use for creating the color
palettes for the rectangles. Per default gray.colors is
used. Be aware that col_fun should accept as first argument an
integer specifying the number of colors to create.
color for background filling.
logical. If set to TRUE (the default),
disordered absolute item threshold parameters are indicated by a
horizontal line (only if type is set to "mode").
character, color of indication lines (if uo_show).
numeric. Line typ of indication lines (if uo_show).
numeric. Line width of indication lines (if uo_show).
numeric. Number of lines used for y-axis labels.