I am interested in fitting multilevel rating scale IRT models with rater effects. I saw Bob Carpenter’s Youtube presentation at MLSS Sydney 2015 where he mentioned a multilevel IRT model with rater effects to show the efficiency of Stan relative to JAGS. I was wondering if the code for this series of models is available anywhere.
Also as suggested by the talk, these models should be challenging to fit. What procedures are used to address these challenges - i.e. guidance on implementing non-centered parameterizations in this context or possibly using Riemannian-manifold HMC.
As a side question, when is Riemannian-manifold HMC likely to be available in Stan. Is it available in a developer version?
Any comments would be appreciated!