Plot the Guttman scalogram

Displays the Guttman-ordered response matrix as a heatmap (dark for high categories), with persons sorted by location down the rows and items by location across the columns. The coefficient of reproducibility is shown in the subtitle.

Usage

plot_guttman(fit, max_persons = 80)

Arguments

fit

A fitted object from rasch.

max_persons

Persons are thinned to at most this many evenly spaced rows for legibility on large samples.

Value

Called for its plotting side effect; invisibly NULL.

Examples

set.seed(1)
d <- seq(-2, 2, length.out = 6)
X <- matrix(rbinom(200 * 6, 1, plogis(outer(rnorm(200), d, "-"))), 200, 6)
colnames(X) <- paste0("I", 1:6)
plot_guttman(rasch(X))