Plot the fit residual distribution — plot_resid

A histogram of the item or person fit residuals – the log-transformed statistic or its untransformed natural form – against the standard normal density they should approximate under fit (Andrich and Marais 2019, ch. 15). The natural residual is visibly skewed (that is why the log transform is reported); both are available.

Usage

plot_resid_dist(
  fit,
  what = c("items", "persons"),
  statistic = c("fit_resid", "natural"),
  bins = 25
)

Arguments

fit: A fitted object from rasch.
what: "items" or "persons".
statistic: "fit_resid" (log-transformed, default) or "natural".
bins: Number of histogram bins.

Value

Called for its plotting side effect; invisibly NULL.

Examples

set.seed(1)
d <- seq(-2, 2, length.out = 10)
X <- matrix(rbinom(400 * 10, 1, plogis(outer(rnorm(400), d, "-"))), 400, 10)
colnames(X) <- paste0("I", 1:10)
plot_resid_dist(rasch(X), what = "persons")