SL {MiscPsycho} | R Documentation |
This function estimates the A and B parameters (interept and slope) such that two tests with common items can be linked. Common items must be multiple choice items based on the 3-parameter logistic model.
SL(...) ## Default S3 method: SL(params1, params2, con = 1e-3, ...)
params1 |
item parameters of the common items used for linking organized as a list of lists for test A. See irt.ability for more details. |
params2 |
item parameters of the common items used for linking organized as a list of lists for test B. See irt.ability for more details. |
con |
Criterion for convergence |
... |
a list of control parameters. These are actually passed from the function SLderivs ,
|
A list with class "SL"
containing the following components:
A.Parameter |
The Stocking-Lord intercept |
B.Parameter |
The Stocking-Lord slope |
A Parameter |
Mean/Sigma intercept used as the starting values |
B Parameter |
Mean/Sigma slope used as the starting values |
Harold Doran
Kolen, M.J., Brennan, R.L. (2004). Test equating, scaling, and linking. Second Edition. Springer.
## This is 3PL and are values from page 171 of Kolen and Brennan params1 <- list("3pl" = list(a = c(.4,1.7,1.2), b = c(-1.1, .9,2.2), c = c(.1,.2,.1)), "gpcm" = NULL) params2 <- list("3pl" = list(a = c(.5,1.6,1), b = c(-1.5, .5,2), c = c(.1,.2,.1)), "gpcm" = NULL) SL(params1, params2, control=list(Q=30, mu=0, sigma=1))