Estimate ability scores from a 2PL calibration — score

Computes bounded maximum-likelihood ability estimates for response patterns under fixed item parameters. This is a scoring helper for inspecting fitted calibrations; it does not account for uncertainty in the item parameters.

Usage

score_theta(resp, item_pars, bounds = c(-6, 6))

Arguments

resp: Response matrix with rows for subjects and columns for items.
item_pars: Item parameters in slope-intercept form. Supply a data frame or matrix with columns a/a1 and d, or a fitted mirt model.
bounds: Numeric vector of length two giving the optimization interval for theta.

Value

A numeric vector of ability estimates.

Examples

set.seed(1)
pars <- data.frame(a = c(1, 1.2), d = c(0, -0.5))
resp <- simulate_2pl(rnorm(5), pars)
score_theta(resp, pars)
#> [1] -5.9999390  5.9999241  0.4122068  5.9999241  0.4122068