refers to both the level of agreement/consistency on the diagnosis by different psychiatrists across time and cultures (inter rater) and the consistency of diagnosis over time given no change in symptoms (test-retest)

psychiatrists independently diagnose 100 patients using both DSM and ICD criteria. found that the number were different between the two psychiatrists, demonstrating that there was poor reliability between the two psychiatrists

strength- evidence to suggest diagnosis/classification is reliable as classification systems provide a common language for clinicians, which enables them to communicate with each other about a disorder. reported concordance rate of 81% using DSM diagnostic system, suggesting good level of agreement between doctors

practical application- due to difference in number of diagnosis between 2 psychiatrists there have been improvements in the manuals. DSM and ICD are now very similar in the wording about Sz and training is offered to allow there to be a better u derstanding of the manuals and how to use them. allows for greater reliability in diagnosis

refers to the extent that a diagnosis represents something that is real and distinct from other disorders

the extent to which a classification system such as the DSM measures what it claims to measure

strength- evidence to suggest issue with validity in diagnosis as ptpts fakes symptoms of sz and were admitted to hospital and diagnosed with sz and one was diagnosed with bipolar disorder. demonstrates problem with validity as none of the people had sz but were admitted to hospital for average of 19 days.

limitation- problems with generalisability in research was has small sample size in that only 12 hospitals were used. not representative of general population so results should be taken with care

where 2 conditions co-exist in the same individual at the same time, so a person with Sz may also be suffering with depression

can lead to problems with diagnosis for patient, which questions validity of method

strength- evidence to suggest there is co-morbity in Sz, as research found that 50% of individuals with a diagnosis of Sz also have depression. this questions the validity of the diagnosis as means that Sz may not be a distinct disorder

practical application- idue to high prevalence of different disorders being present at same time this has implications on treatments for patients as can effect the effectiveness of treatments given. the implications of a better awareness and more research into co morbidity is that people with Sz will then have a more effective treatment options

concerns the way in which members of other cultures are more likely to be diagnosed with sz

strength- evidence to suggest culture bias in diagnosis as found afro-caribbean patients 10x more likely to be diagnosed . some cultures believe and are praised for being able to communicate with spirits so are more likely to report these experiences and can be misinterpreted as symptoms of sz leading to the over-diagnosis of certain cultural groups

practical application- to account for this cultural bias in diagnosis there have been changes made to the dam-v, adding a section to account for cultural related diagnostic issues and demonstrating differences in symptoms for other cultures which improves accuracy of diagnosis

in Britain, people of afro-caribbean descent are more likely to be diagnosed with sz and more likely to be kept in secure hospitals

disagreement about the gender prevalence rate of sz as previously thought males and females were equally vulnerable

strength- evidence to support gender bias as research found more men than women have been diagnosed. may be because men more genetically vulnerable or bc female patients function better so a diagnosis may be missed. may be that women less likely to receive appropriate treatement

practical application- to account for gender bias changes have been made to dsm-v, adding a section to account for gender related dignostic issues which allows psychiatrists to have better understanding and improving accuracy of diagnosis

considerable overlap between symptoms of sz and other disorders such as bipolar. means hard to define boundaries between sz and other disorders

occurs when a person is diagnosed with sz and these negative labels are hard to remove. wrong diagnosis means someone risks carrying stigma for rest of life

wrong diagnosis can lead to wrong treatment being given. serious due to side effects

strength- evidence to suggest symptoms overlap in diagnosing of sz as research found that ppl with dissociative identity disorder have more symptoms of sz than those diagnosed with sz. this wrongful diagnosis of sz means could be problems with treatment

practical application- real world implication of symptom overlap as can lead to delay of treatment or misdiagnosis. by focusing more on symptom overlap can have positive outcome on those suffering