etiological validity-group of people who have been diagnosed with the same disorder will have the same factors causing it. e.g. Schizophrenia being caused by an excess of dopamine should mean all patients with Schizophrenia should have an excess of dopamine
concurrent validity-symptoms that form a part of the disorder but are not a part of the actual diagnosis, should be found in every patient diagnosed.
Predictive validity-if present, it can lead to a predicition of a disorder's diagnosis in the future. Should be able to say whether ot not the symptoms will continue or whether they will recover. It should be possible to predict the outcome of treatments
Cooper et al in 1972 found that New York psychiatrists were more likely to diagnoses schizophrenia than London psychiatrists who were more likely to diagnose mania and depression when shown the same video tapes