Plot a kidmap — plot_kidmap • rasch

The person diagnostic map (Wright, Mead and Ludlow 1980): item thresholds the person achieved to the right of a vertical logit axis and thresholds not achieved to the left, with the person's location drawn as a dashed line inside its confidence band. Achieved thresholds above the band (unexpected successes) and unachieved thresholds below it (unexpected failures) are highlighted; a clean response pattern shows achieved thresholds below the band and unachieved ones above it.

Usage

plot_kidmap(
  fit,
  person,
  level = 0.95,
  bins = 35,
  xlim = NULL,
  cex_labels = 0.8
)

Arguments

fit: A fitted object from rasch.
person: Row number of the person, or an ID matching fit$person$id.
level: Confidence level of the band around the person location used to mark unexpected responses.
bins: Number of vertical bins used to stack the threshold labels.
xlim: Optional logit range; thresholds outside it are omitted.
cex_labels: Character expansion for the threshold labels.

Value

Called for its plotting side effect; invisibly NULL.

References

Wright, B. D., Mead, R. J., & Ludlow, L. H. (1980). KIDMAP: person-by-item interaction mapping (Research Memorandum No. 29). Chicago: University of Chicago, MESA Psychometric Laboratory.

Examples

set.seed(1)
d <- seq(-2, 2, length.out = 12)
X <- matrix(rbinom(300 * 12, 1, plogis(outer(rnorm(300), d, "-"))), 300, 12)
colnames(X) <- paste0("I", 1:12)
plot_kidmap(rasch(X), person = 1)