[R-sig-ME] IRT: discrimination parameters from LMER?

[dave fournier]

If you need a more flexible modeling platform you could look at
AD Model Builders  random effects package.
There is an example there incorporating extra parameters
into the model for an example of Dorans.  The
extra parameters significantly improved the fit.


http://admb-project.org/community/tutorials-and-examples/random-effects-example-collection