Assessing construct validity of the self-rating version of the European Brain Injury Questionnaire (EBIQ) using Rasch analysis

Data from the European Brain Injury Questionnaire (EBIQ) responses of 226 consecutive admissions to the Oliver Zangwill Centre were analysed using Rasch analysis (Item Response Theory) techniques with the software package RUMM2020. Some items and overall scales did not meet the expectations of the Rasch model. After removal of items it was possible to validate six subscales from previously published subscales, namely: cognitive, impulsivity, somatic, depression, communication and difficulties in social interactions. A new EBIQ fatigue subscale is also proposed.