extract_params: Extract Item Parameter Estimates from a Fitted mirt Model...

In irtsim: Monte Carlo Simulation-Based Sample-Size Planning for Item Response Theory

Extract Item Parameter Estimates from a Fitted mirt Model (Internal)

Description

Pulls point estimates, SEs, and CIs from a fitted mirt object and returns them in long format matching the item_results schema.

Usage

extract_params(
  mod,
  design,
  estimation_model,
  iteration,
  sample_size,
  true_params,
  true_params_lookup,
  se = TRUE
)

Arguments

mod	A fitted mirt object.
design	An irt_design object (for true values and model type).
estimation_model	Character string: "1PL", "2PL", or "GRM" (the model that was fitted, which may differ from design$model).
iteration	Integer iteration number.
sample_size	Integer sample size.
true_params	Data frame (used for schema).
true_params_lookup	Named character vector mapping keys of the form "item_param" (e.g., "Item_1_a") to true_value (for O(1) lookup instead of repeated vector scans).
se	Logical. Extract standard errors and CIs? Default TRUE.

Details

Uses the list-based coef(mod) output (one matrix per item, keyed by item name). Default coef() returns rows ⁠par, CI_2.5, CI_97.5⁠; SE is derived from CI width: SE = (upper - lower) / (2 * z_0.975).

Value

Data frame with item_results columns.

irtsim documentation built on April 24, 2026, 1:07 a.m.