irtc_itemfit: Item Fit Statistics (Infit and Outfit)

In IRTC: Marginal Maximum Likelihood Estimation for Item Response Models

Item Fit Statistics (Infit and Outfit)

Description

Residual-based item fit for a fitted model: infit and outfit mean squares with Wilson-Hilferty t statistics, evaluated at the EAP person estimates. Values near 1 indicate good fit; the conventional normal range is 0.7 to 1.3.

Usage

irtc_itemfit(mod, resp = NULL)

## S3 method for class 'irtc_itemfit'
print(x, lang = irtc_lang(), ...)

Arguments

mod	A fitted irtc model object.
resp	The response data; only needed when the model object does not store it (streaming engine).
x	An irtc_itemfit object.
lang	Output language, "zh" or "en".
...	Ignored.

Value

A data frame of class irtc_itemfit with columns item, N, outfit, outfit_t, infit, infit_t.

See Also

irtc_quality, irtc_ctt

Examples

set.seed(1)
theta <- rnorm(200)
resp <- as.data.frame(sapply(seq(-1, 1, length.out = 5), function(b) {
    as.numeric(runif(200) < plogis(theta - b))
}))
mod <- irtc.mml(resp = resp, verbose = FALSE)
irtc_itemfit(mod)

IRTC documentation built on July 24, 2026, 5:07 p.m.