Plot the person-item threshold distribution

The targeting display: the person location distribution above the axis and the calibration threshold distribution mirrored below it, on a shared logit scale. Dashed lines mark the person and threshold means in their distributions' colours. MFRM and EFRM thresholds belong to response cells.

Usage

plot_pimap(
  fit,
  bins = 35,
  xlim = NULL,
  information = FALSE,
  group = NULL,
  items = NULL
)

Arguments

fit: A fitted object from rasch.
bins: Number of histogram bins.
xlim: Optional logit range for the shared scale; persons and thresholds outside it are omitted. By default the range is extended to labelled tick marks beyond the most extreme plotted estimate.
information: Whether to overlay the test information function on a separate right-hand axis. Fits with more than one administrable design receive one curve per design.
group: Optional person-group level: one level of a fitted person factor, restricting the person distribution to those persons. A level no fitted factor carries is an error.
items: Optional item selection restricting the threshold distribution: item names, or one item-set name of an extended-frame fit, whose virtual item-by-group cells match through their underlying items. The selection is named in the legend, so a restricted map cannot be read as the whole instrument. The information curve follows the same item selection; for an extended-frame fit it also follows the response cells occupied by the selected person group. For EFRM and MFRM, only response patterns present in that person group are shown.

Value

Called for its plotting side effect; invisibly NULL.

Examples

set.seed(1)
d <- seq(-2, 2, length.out = 6)
X <- matrix(rbinom(400 * 6, 1, plogis(outer(rnorm(400), d, "-"))), 400, 6)
colnames(X) <- paste0("I", 1:6)
plot_pimap(rasch(X))