Draw a Wright map with WrightMap

Prepares person estimates and item locations from a fitted model and passes them to WrightMap::wrightMap(). Person panels may be formed from variables retained in the fit or supplied as a matrix. Item panels use the item.groups facility in WrightMap 1.5.

Usage

wright_map(
  fit,
  type = c("thresholds", "locations"),
  person_panels = NULL,
  item_panels = NULL,
  ...
)

Arguments

fit: A fitted object from rasch, including explanatory, MFRM and EFRM fits. Comparative-judgement models do not estimate person locations and are not supported.
type: Plot category "thresholds" or one "locations" estimate per item.
person_panels: Optional person-panel specification. Supply the name of one or more variables retained in fit$person, a vector or factor of panel memberships with one value per person, or a numeric matrix or data frame whose columns contain the estimates for the panels. Missing estimates are permitted. For EFRM fits, "groups" uses the fitted person groups.
item_panels: Optional vector or factor assigning each item row to a panel. A named vector is matched to item names; an unnamed vector is used in item order. A named list may instead map panel names to item names. For EFRM fits, use "sets", "groups", or c("sets", "groups") to arrange the calibrated response columns by item set, person group, or frame. This option requires WrightMap 1.5 or later.
...: Further arguments passed to WrightMap::wrightMap(), such as person.side, item.side, main.title, or graphical settings.

Value

Invisibly, the threshold matrix returned by WrightMap::wrightMap() when its return.thresholds argument is true; otherwise NULL.

Details

For partial credit and rating scale models, type = "thresholds" displays each item's estimated category thresholds, labelled t1, t2, and so on. A wholly dichotomous scale omits the redundant t1 labels; in a mixed scale, dichotomous items retain t1 to align them with the polytomous items. type = "locations" displays one location per item. In MFRM and EFRM fits, the rows are the calibrated item-by-facet or item-by-frame response columns. For EFRM fits, person_panels = "groups" and item_panels = "sets" use the fitted frame design; both may be specified together. A single person panel has no heading by default. When several person panels are requested, their panel labels are printed above the distributions. The plot has no overall title unless one is supplied through main.title.

References

Torres Irribarra, D., and Freund, R. (2025). WrightMap: IRT item-person map with ConQuest integration. R package version 1.5.

Examples

set.seed(1)
d <- seq(-2, 2, length.out = 6)
X <- matrix(rbinom(300 * 6, 1, plogis(outer(rnorm(300), d, "-"))), 300, 6)
colnames(X) <- paste0("I", 1:6)
fit <- rasch(X)
if (requireNamespace("WrightMap", quietly = TRUE)) {
  wright_map(fit)
}