plot_PImap function

Plot The Person-Item Map

This function maps the distribution of the persons' abilities and the items difficulties along the latent continuum.

plot_PImap(
  obj,
  main = NULL,
  xlab = NULL,
  cex = NULL,
  cex.lab = NULL,
  cex.axis = NULL,
  cex.main = NULL,
  lwd = NULL,
  v = NULL,
  th_dif = 1e-05
)

Arguments

• obj: The object of class 'pcm'.
• main: main title of the plot; see plot.default().
• xlab: Label for the x-axis; see plot.default().
• cex: A numerical value giving the amount by which plotting text and symbols should be magnified relative to the default; see par().
• cex.lab: The magnification to be used for x and y labels relative to the current setting of cex; see par().
• cex.axis: The magnification to be used for axis annotation relative to the current setting of cex; see par().
• cex.main: The magnification to be used for main titles relative to the current setting of cex; see par().
• lwd: The line width, a positive number, defaulting to 1; see par().
• v: Variable names used
• th_dif: The threshold at which a DIF effect is still considered a DIF.

Returns

There are no values to return. Instead, it shows a graphical map of the estimated ability and the estimated difficulty on the same scale.

Examples

## Not run:

groupsMap <- matrix(c(rep(1,50),rep(0,50)),ncol = 1, dimnames = list(c(1:100),c("V1")))
pcmdif_res <- pcm_dif(shortDIF, groups_map = groupsMap)
plot_PImap(pcmdif_res)
## End(Not run)