An individual who is failing to continue with their normal everyday activities, such as going to work, washing or taking part in social activities, would be considered abnormal using this definition
We can usually interpret the behaviour of others as being rational, but if the behaviour does not seem to be rational and hard to understand it can suggest there is a problem
DSM V uses the World Health Organsization Disability Assessment Schedule 2 (WHODAS 2.0) which is a self-report assessment tool that evaluates the patient's ability to perform activities in six areas of functioning (eg, communicating, self-care) over the previous 30 days
This is beneficial as if we have an objective judgement of abnormality, we are more likely to have a reliable (and consistent) diagnosis of abnormality
This is because it considers the individual's own personal distress and suffering when deciding whether someone is suffering from an abnormality or not
This supports FFA as if other people (such as clinicians) are solely responsible for deciding whether somebody is abnormal this can be interpreted subjectively depending on the person who is deciding
Harold Shipman murdered 215 of his patients over a 23 year period and this was undetected by others and he did not appear to function inadequately at all