Test Information Function — plot

Shows where on the ability scale the test is most precise. In Rasch, item info = P(1-P), which peaks at ability = difficulty. Test info = sum of all item infos.

Usage

plot_info(
  object,
  items = NULL,
  theta_range = c(-4, 4),
  show_items = FALSE,
  ...
)

Arguments

object: A birt_fit object.
items: Which items to include. Default: all.
theta_range: Range of ability values. Default c(-4, 4).
show_items: Show individual item curves? Default FALSE.
...: Ignored.

Value

A ggplot2 object.