Building a Unidimensional Test Using Multidimensional Items

Abstract

This paper demonstrates, both theoretically and empirically, using both simulated and real test data, that sets of items can be selected that meet the unidimensionality assumption of most item response theory models even though they require more than one ability for a correct response. Sets of items that measure the same composite of abilities as defined by multidimensional item response theory are shown to meet the unidimensionality assumption. A method for identifying such item sets is also presented