AO3

• Cheniaux et al. (2009) found that when two psychiatrists assessed the same clients, using both ICD and DSM, that 68 were diagnosed with the ICD and only 39 under the DSM.
• Culture bias - Fernando argues people with afro carribean heritage in UK are up to 9x more likely to be diagnosed due to category failure when western definitions of mental illnesses are applied to people from non-western cultures
• Beck et al (1962) found 153 patients diagnosed with multiple doctors had only 54% concordance rate showing low inter-rater reliability
• Copeland et al (1971) gave psychiatrists in the UK and US a description of a patient, 69% US diagnosed as a schizo, 2% UK diagnosed as schizo questioning reliability of diagnosis same symptoms with different diagnoses
• Osario et al. (2019) found inter-rater reliability of +0.97 and +0.92 for test-retest reliability in diagnosis of Schizophrenia. However, some would state that of reliability is still an issue in diagnosis. Whaley found that when using the DSM-IV, inter-rater reliability correlations were as low as 0.11.
• Rosenhan - 'Being sane in insane places'. All 8 patients were diagnosed with mental health issues and admitted to the psychiatric wards, despite them faking their initial symptoms. This study highlighted the unreliability of the diagnostic systems being used at the time. However, this study did take place over 40 years ago and diagnostic manuals have since been updated. For example, categories and definitions are more detailed and operationalised and psychiatrists now use standardised interview schedules when assessing patients.
• Rosenhan, 8 volunteers pretended to have schizo, all admitted but took 7-52 days for them to be released, shows diagosis lacks validity as psychiatrists can't distinguish between real and pseudo patients. However, the expectation effect may have impacted the results of this study - doctors looked for evidence of illness and nervousness of volunteers contributed, diagnosis is a sticky label with serious consequences yet is manufactured by psychiatrists with low degrees of accuracy
• Predictive validity: diagnosis led to successful treatment - Cotton et al argues women's experience of schizo is taken less seriously and underdiagnosed due to better social coping strategies (gender bias)
• Descriptive validity: patients are different to patients who have other disorders - Buckley et al found co-morbidity rates with schizo: depression 50%, drug abuse 47%, PTSD 29%, OCD 23% suggesting schizophrenia may not exist as one condition 
• Konstantareas and Hewitt compared 14 autistic patients with 14 schizophrenic patients and found no schizophrenics had symptoms of autism but 7 had symptoms of schizophrenia suggesting an association between schizophrenia and autism (symptom overlap)
• Aeteological validity: cause should be the same for valid diagnosis - Baille et al questioned psychiatrists about causes of schizophrenia, found differing views