mirt (version 1.3)

plot-method: Plot various test implied functions from models

Description

Plot various test implied response functions from models estimated in the mirt package.

Usage

## S3 method for class 'ExploratoryClass,missing':
plot(x, y, type = "info", npts = 50,
  theta_angle = 45, theta_lim = c(-4, 4), which.items = 1:ncol(x@data),
  rot = list(xaxis = -70, yaxis = 30, zaxis = 10), facet_items = TRUE,
  auto.key = TRUE, main = NULL, drape = TRUE, colorkey = TRUE,
  ehist.cut = 1e-10, add.ylab2 = TRUE, ...)

Arguments

x

an object of class ExploratoryClass, ConfirmatoryClass or MultipleGroupClass

y

an arbitrary missing argument required for R CMD check

type

type of plot to view; can be 'info' to show the test information function, 'infocontour' for the test information contours, 'SE' for the test standard error function, 'trace' and 'infotrace

theta_angle

numeric values ranging from 0 to 90 used in plot. If a vector is used then a bubble plot is created with the summed information across the angles specified (e.g., theta_angle = seq(0, 90, by=10))

theta_lim

lower and upper limits of the latent trait (theta) to be evaluated, and is used in conjunction with npts

npts

number of quadrature points to be used for plotting features. Larger values make plots look smoother

rot

allows rotation of the 3D graphics

which.items

numeric vector indicating which items to be used when plotting. Default is to use all available items

facet_items

logical; apply grid of plots across items? If FALSE, items will be placed in one plot for each group

auto.key

logical parameter passed to the lattice package

ehist.cut

a probability value indicating a threshold for excluding cases in empirical histogram plots. Values larger than the default will include more points in the tails of the plot, potentially squishing the 'meat' of the plot to take up less area than v

main

argument passed to lattice. Default generated automatically

drape

logical argument passed to lattice. Default generated automatically

colorkey

logical argument passed to lattice. Default generated automatically

add.ylab2

logical argument passed to lattice. Default generated automatically

...

additional arguments to be passed to lattice

Examples

x <- mirt(Science, 1)
plot(x)
plot(x, type = 'trace')
plot(x, type = 'infotrace')
plot(x, type = 'infotrace', facet_items = FALSE)
plot(x, type = 'infoSE')

set.seed(1234)
group <- sample(c('g1','g2'), nrow(Science), TRUE)
x2 <- multipleGroup(Science, 1, group)
plot(x2)
plot(x2, type = 'trace')
plot(x2, type = 'trace', which.items = 1:2)
plot(x2, type = 'trace', which.items = 1, facet_items = FALSE) #facet by group
plot(x2, type = 'score')

x3 <- mirt(Science, 2)
plot(x3)
plot(x3, type = 'SE')