An approach was developed based on item-response models defined at the level of salient subject groups rather than at the level of individuals, designed for use with multiple-matrix sampling designs. In each of three National Assessment of Educational Progress (NAEP) mathematics subtopics, Reiser's group-effects latent trait model was fitted to…

In studies involving matrix sampling on items, it is often the case that there are too few responses per individual to use latent trait item response models. A model is formulated wherein individual level variability appears as independent error within the cells of a cross classification of demographic variables. (JKS)