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Simulation-Based Infit MSQ Cutoff Determination

Source: R/infit_cutoff.R
RMitemInfitCutoff.Rd

Uses parametric bootstrap simulation to determine appropriate cutoff values for RMitemInfit. This function simulates data from a correctly fitting Rasch model that mimics your data and returns per-item empirical cutoffs.

Usage

RMitemInfitCutoff(
  data,
  iterations = 250,
  parallel = TRUE,
  n_cores = NULL,
  verbose = FALSE,
  seed = NULL,
  cutoff_method = "hdci",
  hdci_width = 0.999
)

Arguments

data

A data.frame or matrix of item responses. Items must be scored starting at 0 (non-negative integers). Only complete cases (rows without any NA) are used.

iterations

Integer. Number of simulation iterations (default 250).

parallel

Logical. Use parallel processing via mirai if available (default TRUE).

n_cores

Integer or NULL. Number of parallel workers. When NULL, getOption("mc.cores") is checked first. If neither is set and parallel = TRUE, a warning is issued and execution falls back to sequential (single core) processing.

verbose

Logical. Show a progress bar (default FALSE).

seed

Integer or NULL. Random seed for reproducibility.

cutoff_method

Character string specifying how cutoff intervals are computed. Either "hdci" (default) for the Highest Density Interval via ggdist::hdci(), or "quantile" for the 2.5th/97.5th percentiles via stats::quantile().

hdci_width

Numeric. Width of the HDCI when cutoff_method = "hdci". Default is 0.999 (99.9% HDCI). Ignored when cutoff_method = "quantile".

Value

A list with components:

results

data.frame with columns iteration, Item, InfitMSQ, OutfitMSQ (one row per item per successful iteration).

item_cutoffs

data.frame with per-item cutoff summaries: Item, infit_low, infit_high, outfit_low, outfit_high. Bounds are computed using the method specified by cutoff_method.

actual_iterations

Number of successful iterations.

sample_n

Number of complete cases used.

sample_summary

Summary statistics of estimated person parameters.

item_names

Character vector of item names from data.

cutoff_method

The method used to compute cutoffs ("hdci" or "quantile").

hdci_width

The HDCI width used (only meaningful when cutoff_method = "hdci").

Details

For each simulation iteration, person parameters (thetas) are resampled with replacement from ML estimates, response data are simulated under the Rasch model, the model is refitted, and conditional infit and outfit MSQ statistics are computed via iarm::out_infit(). The distribution of these statistics across iterations provides empirical critical values per item. Failed iterations (e.g., due to convergence issues or degenerate data) are silently discarded.

Supports both dichotomous data (via eRm::RM() and psychotools::rrm()) and polytomous data (via eRm::PCM() and an internal partial credit score simulator).

Parallel processing is provided by the mirai package (optional). Install it with install.packages("mirai") to enable parallelisation.

The iarm package must be installed (it is in Suggests, not Imports).

See also

RMitemInfit

Examples

# \donttest{
set.seed(42)
sim_data <- as.data.frame(
  matrix(sample(0:1, 200 * 10, replace = TRUE), nrow = 200, ncol = 10)
)
colnames(sim_data) <- paste0("Item", 1:10)

# Run 100 iterations sequentially for a quick demo
cutoff_res <- RMitemInfitCutoff(sim_data, iterations = 100, parallel = FALSE,
                            seed = 42)
cutoff_res$item_cutoffs
#>      Item infit_low infit_high outfit_low outfit_high
#> 1   Item1     0.902      1.152      0.851       1.324
#> 2   Item2     0.873      1.124      0.844       1.161
#> 3   Item3     0.872      1.101      0.822       1.181
#> 4   Item4     0.883      1.131      0.843       1.186
#> 5   Item5     0.884      1.122      0.870       1.191
#> 6   Item6     0.878      1.172      0.808       1.252
#> 7   Item7     0.863      1.132      0.813       1.237
#> 8   Item8     0.922      1.095      0.864       1.173
#> 9   Item9     0.862      1.105      0.866       1.169
#> 10 Item10     0.901      1.129      0.877       1.181

# Use the cutoffs in RMitemInfit()
RMitemInfit(sim_data)
#> 
#> 
#> Table: MSQ values based on conditional estimation (n = 200 complete cases).
#> 
#> |Item   | Infit MSQ| Relative location|
#> |:------|---------:|-----------------:|
#> |Item1  |     1.008|             -0.22|
#> |Item2  |     0.999|              0.14|
#> |Item3  |     0.994|              0.00|
#> |Item4  |     1.055|             -0.04|
#> |Item5  |     1.004|              0.10|
#> |Item6  |     1.032|             -0.08|
#> |Item7  |     0.943|             -0.04|
#> |Item8  |     0.988|             -0.02|
#> |Item9  |     0.933|              0.12|
#> |Item10 |     1.044|              0.39|
# }