ABSTRACT
This chapter is a comprehensive reference manual providing information on the Overt Behaviour Scale (OBS), which is primarily a clinician rating scale, although it can also be used as an observational instrument. It was designed to measure common challenging behaviours, suitable for people with acquired brain impairment (ABI) living in the community. The OBS categories are designed to be administered in a set order so that “double-counting” of behaviours that may fit multiple categories is avoided. The OBS is, however, quite a complex instrument. The scoring format is initially difficult to grasp, with scores for clusters, levels, total clinical weighted severity levels, frequency and impact. A brief history of the instrument's development is provided, along with a description of item content and administration/scoring procedures. Psychometric properties are reviewed and a critical commentary is provided. Key references are cited and in most cases the actual scale is included, giving the reader easy access to the instrument.
