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irtsim

CRAN status CRAN downloads License: GPL v3

Monte Carlo simulation-based sample-size planning for item response theory.

Installation

Quick start 

library(irtsim)

design  <- irt_design(
  model = "1PL", n_items = 20,
  item_params = list(b = seq(-2, 2, length.out = 20))
)
study   <- irt_study(design, sample_sizes = c(200, 400, 800))
results <- irt_simulate(study, iterations = 100, seed = 42)

summary(results)
plot(results)
recommended_n(summary(results), criterion = "rmse", threshold = 0.20)

What it supports

  • Models: 1PL, 2PL, graded response model (GRM)
  • Missingness: MCAR, MAR, booklet designs, linking designs
  • Criteria: MSE, bias, RMSE, SE, coverage, Monte Carlo SE, plus user-defined via criterion_fn
  • Misspecification: generate with one model, fit with another
  • Parallelization: irt_simulate(parallel = TRUE) via future.apply

Reference

Schroeders, U., & Gnambs, T. (2025). Sample size planning in item response theory: A 10-decision framework. Advances in Methods and Practices in Psychological Science. https://doi.org/10.1177/25152459251314798

License

GPL (>= 3)