Detecting and interpreting local item dependence using a family of Rasch models

Abstract

This paper describes a method for detecting and interpreting disturbances of the local independence assumption among items that share common stimulus material or other substantive features. Dichotomous and polytomous Rasch models are used in an example to analyze Structure of the Learning Outcome (SOLO) superitems and examine the results for local independence problems. The results indicate that some disturbances were present among particular subsets of the items. Index terms: local independence, partial credit model, one-parameter logistic model, Rasch model, rating scale model.