Equate IRT scales using anchor item parameters — equate_irt

Implements mean-sigma, mean-mean, Stocking-Lord, and Haebara linking for dichotomous 2PL-style item parameters. New-form parameters are transformed onto the reference scale using theta_ref = A * theta_new + B.

Usage

equate_irt_scales(
  reference,
  new,
  method = c("stocking-lord", "haebara", "mean-sigma", "mean-mean"),
  theta_grid = seq(-4, 4, length.out = 81)
)

Arguments

reference: Reference-scale parameters or data.
new: New-scale parameters or data.
method: Method used for estimation, linking, or comparison.
theta_grid: Grid of latent-trait values used for evaluation.