The assessment of emotional distress experienced by people with an intellectual disability: a study of different methodologies.

The assessment of emotional disorders such as anger, depression and stress among people with an intellectual disability has traditionally used one of three methodologies: ratings by a significant other, a clinical interview or self-report. Despite the widespread use of all three methodologies, there is little research into their equivalence. This paper assesses the convergence among these three approaches for 147 people with a mild or moderate intellectual disability across the affective domains of anger, depression and stress. The results showed the overlap among the three methods to be consistently low, although limited convergence was found between self-report and clinical interview. Ratings by work supervisors discriminated least clearly between anger, depression and stress while self-report was the most discriminating between these three overlapping but conceptually distinct states. Suggestions are made for ongoing research into the methodologies of assessing affective states among people with an intellectual disability.