Complications with assessing disability in care of the aged: when does "does not apply" apply?

Cases of severe disability present both practical and psychometric problems when the disability limits function in domains other than the primary one. A re-analysis of the normative sample for the Multidimensional Observation Scale for Elderly Subjects (MOSES; Helmes, Csapo, & Short, 1987) contrasted different approaches to dealing with its 18 items that include a “does not apply” option. Confirmatory factor analysis was used to compare scoring options for such items. Items were also analyzed using item response theory, which revealed several distinct options for the 18 items in question. Several MOSES items do not need the use of the “does not apply” scoring option. A revision of MOSES to incorporate the revised scoring for those 10 items is in order.