plot_ICC function

Plot The Item Characteristic Curves

This function plots the curve(s) of the estimated ability parameters against the probabilities of responses.

plot_ICC(
  obj,
  itemno = 5,
  xlab = NULL,
  ylab = NULL,
  xlim = c(-10, 10),
  col = c("green4", "darkorange2", "red2"),
  lty = c(1, 1, 1),
  main = NULL,
  ...
)

Arguments

• obj: The object of class 'pcm'.
• itemno: A number of the item that is wanted to be plot.
• xlab: a title for the x axis.
• ylab: a title for the y axis.
• xlim: the x limits (x1, x2) of the plot. Note that x1 > x2 is allowed and leads to a ‘reversed axis’. The default value, NULL, indicates that the range of the finite values to be plotted should be used; see plot.default()
• col: a vector of plotting colors
• lty: a vector of line types.
• main: String. Plot title.
• ...: Further arguments to be passed.

Returns

There are no values to return. Instead, it plots the curve of item characteristics from the model.

Examples

res <- pcm(short_poly_data)
plot_ICC(res, itemno = 4)