Beck and Inter-rater reliability
Beck conducted a study which found that psychiatrists agreed on the diagnosis of a person only 54% of the time. in the same country.
This suggests that inter-rater reliabilty may not just be low becasue of the use of different diagnostic mannuals but is different due to what degree of severity the charactorist must be before it is concluded to be a symptom
A counter argument can be added here, by saying that without the use of any diagnostic mannuals the inter-rater reliabilty would be even lower.
Copeland and Inter-rater reliabilty
Copeland asked British and American clinicians to diagnose a person.
He found that where 69% of the American clinicians had given the diagonosis of schizophrenia only 2% of the British clinicians had given the same diagonsis.
This shows that there is a lack of inter-rater reliabilty in the diagnosis of schizophrenia.
This could be due to the use of different diagnostic mannuals.
This suggests that the use of different diagnositic mannuals leads to low inter-rater reliabilty between professtionals.
This is because where American clinicians use the DSM-V British Clinicains use the ICD-10.
Revisions to the Diagnostic Manuals and Construct
Changes the the DSM and ICD indicae that there is low construct vailidty in the diagnosis and classification of schizophrenia.
This is evident from the addion to the mannuals of subtypes of achizophrenia. However these have now been taken out of the the DSM but not the ICD.
This shows that the mannuals are still open to change indicating that professionals are still not sure of all schizophrenic clinical charactorisics.
The fact that they have been taken out of one mannual but not the other shows further a lack of conflict validity as it shows that neither manual is based on fact.
Another example of this that bizzare deulsions could allow an automatic diagnosis of schizophrenia but have now been removed completly from the mannuals.
Bizarre Delusions and Construct validity
Bizarre deusions have now been removed from both diagnosic mannuals however when it was in those diagnosic mannuals it was possible to diagnose aperson with schizophrenia just based on those deusions.
Research done when bizarre delusions were in the manuals shows that when 50 senior clinicians were asked what a bizarre deulsion was, they all responded very differently.
Lopez and Culture in diagnosing schizophrenia
Lopez found that African Americans were more likey to be diagnosed with schizophrenia than any other group.
They were also more likely to be admitted to psychiatric hospitals where they were more likely to be given mojor tranquillisers and ECT therapy.
This shows that some groups are diagnosed more than other social groups as they may be more up front with their symptoms whereas others may not be.
This could lead to misdiagnosis, such as someone being diagnosed with schizophrenia when they have temperol lobe epliepsy.
Misdiagnosis and Culture in diagnosing Schizophren
The person may be misdiagnosed as having schizophrenia when they have something similar such as temperol lobe epilepsy.
This may lead them to become discriminated against such as not being able to find work, becasue the potenial employers do not want to employ someone with schizophrenia.
They may become isolated frm friends if they do not want to be friends with someone with the diagnosis of schizophrenia.
Because of this label they may start to act more like a schizophrenic would and may 'become' schizophrenic.
This would suggest that the clinical charactoristics have not been constructed well as it is open to misdiagnosis.
Misdiagnosis, Co-morbidity and Aetiological Validi
As there is no definitve casue for the condition there is no definitive test leaving it open to misdiagnosis and co-morbidity.
This means that a person may have an illness similar to but not the same as schizophrenia but may be diagnosed with schizophrenia or may have an illness at the same time as schizophrenia but is only diagnosed with schizophrenia.
Examples include depression (avolition and affective flattening), Disociative personality disorder (Disorganised behaviour) and Temporal Lobe Epilepsy (Hallusinations and disorganised speech)
This could lead the person to become labelled as schizophrenic causing people to treat them like that.