Skip to contents

Import an mirt fit to an mfrmr-compatible bundle

Source: R/api-import.R
import_mirt_fit.Rd

Extracts item, step, and person parameters from a mirt::mirt() fit and returns an mfrm_imported_fit object. The returned object has the public slots summary, facets$person, facets$others, steps, config, and source that the mfrmr plot and table helpers expect. With compute_fit = TRUE the importer also runs mirt::itemfit() and mirt::personfit() so Infit / Outfit columns are populated, and synthesises a mfrm_diagnostics-shape diagnostics slot consumable by downstream plot helpers (Wright map, QC dashboard, etc.).

Usage

import_mirt_fit(
  fit,
  model = c("RSM", "PCM", "GPCM"),
  item_facet = "Item",
  compute_fit = FALSE
)

Arguments

fit

An object returned by mirt::mirt() (a SingleGroupClass).

model

One of "RSM", "PCM", "GPCM". The importer does not infer the model from the mirt object; pass the model that was estimated.

item_facet

Name to assign to the item facet in the imported bundle (default "Item").

compute_fit

Logical. When TRUE, run mirt::itemfit() and mirt::personfit() to populate Infit / Outfit / OutfitZSTD columns on the returned facet tables, plus build a measurement-side mfrm_diagnostics bundle consumable by summary(), plot.mfrm_fit(), plot_qc_dashboard(), etc. Default FALSE keeps the importer fast (skeleton only).

Value

An mfrm_imported_fit object. Slots:

summary

Model / method / N / LogLik / AIC / BIC.

facets$person

Person ID, Estimate, SE, Extreme, plus Infit / Outfit / OutfitZSTD / Zh when compute_fit = TRUE.

facets$others

Item-level estimates and slopes; with compute_fit = TRUE, also Infit / Outfit / S_X2 / RMSEA / df from mirt::itemfit().

steps

Per-item threshold parameters extracted from the IRT parameterisation (b1, ..., b(K-1)).

config

List with the resolved model and item_facet used for the import; downstream plot and table helpers consult this to dispatch correctly on the imported bundle.

diagnostics

mfrm_diagnostics-shape bundle when compute_fit = TRUE; NULL otherwise.

source

Imported-from metadata.

Scope

Bundles bias / DIF / anchor / replay slots are explicitly not populated. This helper provides a one-way fitted-object import for the documented core fields, not a bidirectional interchange format.

See also

import_tam_fit(), import_erm_fit()

Examples

# \donttest{
if (requireNamespace("mirt", quietly = TRUE)) {
  response_matrix <- matrix(sample(0:3, 60, replace = TRUE), nrow = 20)
  colnames(response_matrix) <- paste0("Item", seq_len(ncol(response_matrix)))
  fit <- mirt::mirt(response_matrix, 1, itemtype = "gpcm", verbose = FALSE)
  imported <- import_mirt_fit(fit, model = "GPCM")
  imported$summary
}
#> "Item2" re-mapped to ensure all categories have a distance of 1
#> Warning: EM cycles terminated after 500 iterations.
#>   Model Method Source  N Persons Facets Categories    LogLik      AIC     BIC
#> 1  GPCM    MML   mirt 20      20      1         NA -71.49995 164.9999 175.953
#>   Converged ConvergenceStatus
#> 1     FALSE            review
# }