Fig. 1From: Rasch analysis suggests that health assessment questionnaire II is a generic measure of physical functioning for rheumatic diseases: a cross-sectional studyThe item-characteristic curve (ICC) for item 2 (opening car doors). This plots the expected response to item 2 based on the individuals’ level of disability (person location). The curves for each disease category are superimposed upon the Rasch model (gray line). DIF would be implied by a significantly different location of a disease-specific ICC. RA (rheumatoid arthritis), IA (inflammatory arthritis), INF (inflammatory disorder), AICTD (autoimmune connective tissue disease)Back to article page