The saltus model applied to proportional reasoning data.

This chapter examines an application of the saltus model, a mixture model that was designed for the analysis of developmental data. Some background in the types of research for which such a model might be useful is discussed. The equations defining the model are given, as well as the model's relationship to the Rasch model and to other mixture models. An application of the saltus model to an example data set, collected using Noelting's orange juice mixtures tasks, is examined in detail, along with the control files necessary to run the software, and the output file it produced.