This module is an ALIAS. The response function is implemented once, in
Mirt2; the dimension is set by the length of a, not by
the module name, so the only thing this entry point adds is the M2PL
restriction c = 0 and a check that exactly three slopes were
supplied.
Usage
Mirt3(y, theta, a, d, D = 1)
Arguments
- y
Binary 0/1 responses, length n.
- theta
Ability matrix, n by 3.
- a
Item slopes, length 3.
- d
Item intercept.
- D
Metric constant.
Value
As Mirt2: estimate, loglik, p, pbar, deviance, n, m.
Details
P(x = 1 | theta) = 1 / (1 + exp[-D (a1 t1 + a2 t2 + a3 t3 + d)]).
References
Chalmers (2012), Journal of Statistical Software 48(6),
1-29, doi:10.18637/jss.v048.i06
, eq. (1) p.3, with gamma = 0.
Examples
set.seed(18)
theta <- matrix(rnorm(300), 100, 3)
y <- rbinom(100, 1, plogis(theta %*% c(1, 0.5, 0.8)))
Mirt3(y, theta, a = c(1, 0.5, 0.8), d = 0)$loglik
#> [1] -51.44609
