irtoys (version 0.1.5)

tsc: True scores with standard errors

Description

Computes the IRT true scores (test response function at the estimated ability) and an estimate of their standard error via the delte theorem, treating item parameters as known).

Usage

tsc(ip, theta)

Arguments

ip

Item parameters: a matrix with one row per item, and three columns: [,1] item discrimination $a$, [,2] item difficulty $b$, and [,3] asymptote $c$.

theta

An object containing ability estimates, as output by function mlebme or eap

Value

• A matrix with the true scores in column 1, and their standard errors of measurement (SEM) in column 2

See Also

mlebme, eap, trf

Examples

p.2pl <- est(Scored, model = "2PL", engine = "ltm")
th <- mlebme(resp = Scored, ip = p.2pl)
tsc(p.2pl, th)