Hi,

We are doing a ConQuest analysis of a language proficiency test. We intend

to compare four models: a unidimensiona Rasch model, an MRCMLM with 6

factors and between-item multidimensionality, an MRCMLM with 5 factors and

between-item multidimensionality, and a testlet model (with one general

dimension and six specific factors). We want to compare the relative fits

of the models. I have a couple of questions and would be grateful to

receive an explanation from you.

1. Is the deviance statistic reported in ConQuest equal to the -2 Log

Likelihood statistic? Is it the same as G2 reported in Rasch papers?

2. How is the AIC and BIC statistics computed from deviance? (I know these can be estimated from chi-square but is an overall chi-square reported in ConQuest?)

3. Can we consider the testlet model to also have a hierarchical relation

to other models in our study? (so that we can compare their relative fit using the difference in their deviance indices).

Many thanks in advance.

Navid