evaluation of failure to function:
+ matches sufferers perceptions as most people seeking clinical help believe that they are suffering from psychological problems that interfere with the ability to function properly
+ assesses degree of abnormality as the GAF is scored on a continuous scale, it allows clinicians to see the degree an individual is abnormal
+ observable behaviour - it allows judgement by others of whether individuals are functioning properly
+ checklist - definition provides a practical checklist individuals can use
+ personal perspective - perception of sufferer