Classification and Diagnosis AO3

• what is inter-rater reliability in the context of SZ?

  • occurs when different clinicians make identical independent diagnoses of same patient (different people/clinicans)
• what is test-retest reliability in context of SZ?

  • occurs when tests used to deliver these diagnoses are consistent over time (same person/clinician over time)
• what is validity in the context of SZ?

  • extent to which a diagnosis represents something that is real and distinct from other disorders (are we testing what we want to test, and is it distinct) and the extent that a classification system such as ICD or DSM measures what it claims to measure
• what is descriptive validity in the context of SZ?

  • to be valid, patients with SZ should differ in symptoms from patients with other disorders
• what is predictive validity in the context of SZ?

  • if diagnosis leads to successful treatment, then diagnosis is seen as valid
• what is aetiological validity in context of SZ?

  • to be valid, all SZ should have the same cause for the disorder, but it doesn't, so it might be claimed that because a treatment works, then you can tell something about the disorder in the first place, which isn't necessarily true (treatment-aetiology fallacy)
• how are reliability and validity inextricably linked?

  • if a scientist can't agree who has SZ (low reliability) then questions of what it actually is (validity) becomes essentially meaningless, and vice versa
• what is co-morbidity?

  • when two (or more) medical conditions occur at the same time
  • makes it harder to diagnose and classify SZ accurately
  • becomes more difficult to establish reliability and validity
  • a person with SZ may also be suffering from another disorder like depression, alcoholism etc
• what is symptom overlap?

  • considerable overlap of symptoms because of co-morbidity e.g. bipolar disorder, PTSD etc
  • could lead to unreliable or incorrect diagnosis (not valid)