Reliability & Validity

• Reliability of diagnosis

  Good inter-rater & test-retest reliability

  Osório et al. (2019) found high reliability of the diagnosis for schizophrenia in 180 individuals using the DSM-5

  Pairs of interviews achieved inter-rather reliability of +0.97 and test-retest of +0.92
• Validity of diagnosis

  Low criterion validity

  Cheniaux et al. (2009) had 2 psychiatrists independently asses the same 100 clients using the ICD-10 and DSM-4 criteria and found 68 were diagnosed with schizophrenia under the ICD system and 39 under the DSM-4

  = suggests that schizophrenia is either over or under diagnosed according to the diagnostic system
• Gender bias in diagnosis

  • Since 1980s men have been diagnosed more commonly than women
  • possible explanation is that women are less vulnerable than men, perhaps because of genetic factors
  • Cotton et al (2009) seems that women are under diagnosed because they have closer relationships and hence get support. Leads to women with schizophrenia often functioning better than men
  • Women not receiving diagnosis and treatment that may help them
• Culture bias in diagnosis

  British people of African origin are up to 9x as likely to receive a diagnosis as white British are, although people living in African countries are not

  • likely caused by psychiatrists cultural background
  • this mean African Brits may be wrongly diagnosed

  Escobar (2012) appears to be an over-interpretation of symptoms in black British people. This means that British Africans may be discriminated against by culturally biased diagnostic systems
• Co-morbidity

  Schizophrenia often occurs alongside other conditions (e.g. depression, substance abuse), which questions the validity of classifying it as a distinct disorder
• Symptom overlap

  Symptoms of schizophrenia overlap with other conditions (e.g. bipolar disorder), such as positive symptoms like delusions and negative symptoms like avolition
• Classification issues

  Schizophrenia and bipolar disorder may represent variations of a single condition rather than 2 distinct disorders