Using the Partial Credit Model to Investigate Responses to Structured Subtests

Abstract
This article applies the partial credit model to an assessment situation in which items (termed "superitems" by the developers) have been constructed as subtests sharing a particular set of stimulus materials and according to a neo-Piagetian theory of learning (SOLO). Comparison is made with Guttman scaling, a nonprobabilistic approach. The complementary nature of results from a dichotomous Rasch analysis and the polytomous partial-credit analysis is explored.