RELIABILITY: refers to how repeatable a study is. A reliable diagnosis would be one that is repeatable. VALIDITY: The degree to which information is accurate. A valid diagnosis would be one that is accurate to the patient’s illness.
Biological methods of diagnosis:
blood tests
use of brain imaging technologies such as MRI or PET scans
Psychological methods of diagnoss:
IQ and personality tests
cognitive tasks
interviews
self-report methods
Validity Two types of misdiagnosis – type 1 error (say a patient has a disorder that they do not), type 2 error (say a patient does not have a disorder that they do) To improve validity of diagnoses, doctors use diagnostic manuals. These are diagnostic and statistical manuals of mental health which show common symptoms and behaviours of a person with a particular mental illness. This can be behavioural, cognitive and somatic. Examples of these manuals include:
DSM, tool used by doctors, diagnostic statistic manual (every year they re-new it)
ICD (international classification disorder) not as widely used
Reliablility There are two ways to ensure a valid diagnosis is reliable – two doctors to verify it (inter-rater reliability) or the same doctor to give the same diagnosis on two occasions (test re-test diagnosis).
Supporting studies: Nicholls et al. (2000) Seeman (2007)