Psychology - Paper 3 - Schizophrenia - reliability and validity in diagnosing and classifying

What is a diagnostic system?
A set of possible types of abnormality (classification) and the rules for recognising them (diagnosis). The rules are set out in manuals (DSM and ICD).
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What are the advantages of classification and diagnosis?
Communication, treatment, prognosis, cause.
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What are the issues when classifying and diagnosing SZ?
Misdiagnosis, labelling and historical/cultural context.
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What is reliability?
Whether what the researcher is studying can be deemed as accurate.
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How can reliability be assessed?
Inter-rater -level of agreement on the diagnosis by different psychiatrists accross time and cultures and test-retest - consistency of diagnosis over time given no change in symptoms.
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What is a problem with the diagnostic system?
Copeland et al - gave the same patient descriptions to 134 US and 194 UK psychiatrists. 69% of US diagnosed SZ but only 2% in UK.
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What is a strength of the diagnostics system?
Soderberg et al reported a correlation of 0.81 using the DSM system.
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How can this issue be dealt with?
Improve the manuals
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What is validity?
The extent to which SZ is a unique syndrome with characteristics, symptoms and signs.
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How can validity be assessed?
Descriptive validity - patients with SZ should have different symptoms from patients with other disorders. Predictive validity - a diagnosis is valid if it leads to successful treatment.
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What are the 5 issues affecting validity?
Co-morbidity, gender bias, culture bias, symptom overlap, range of symptoms.
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What is co-morbidity?
Co-morbidity is when two or more conditions occur together.
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What is the evidence for co-morbidity?
Buckley et al. (2009) found that 50% of patients with schizophrenia have depression or substance abuse, 29% PTSD, 23% OCD.
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Why is co-morbidity a problem?
If conditions occur together a lot, like with SZ, this questions the validity of the disorders as they may be one single condition.
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What is the evidence for gender bias?
Longenecker et al. (2010) since the 1980s men have been diagnosed with SZ more than women.
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What could explain this gender bias?
Men may be more genetically vulnerable or female patients function better (more likely to work, maintain good family relationships) than male patients so a diagnosis may be missed
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What is the evidence for culture bias?
Keith et al (1991) found 2.1% of African Americans are diagnosed with SZ compared to 1% of the white population. Many people from African cultures believe and are praised for being able to communicate with ancestral spirits.
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What is symptom overlap?
There is considerable overlap between the symptoms of SZ and other disorders e.g. bipolar disorder. This means it is hard to define boundaries between SZ and other disorders.
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What is range of symptoms?
There are a range of symptoms that could be present for a diagnosis of SZ e.g. positive and negative symptoms. 2 individuals could display very different behaviour but still be diagnosed with SZ.
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What are the implications of these issues?
Labelling/stigmatisation occurs when a person is diagnosed with a condition like SZ and these negative labels are hard to remove. A wrong diagnosis means someone risks carrying the stigma for the rest of their lives.
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Other cards in this set

Card 2


What are the advantages of classification and diagnosis?


Communication, treatment, prognosis, cause.

Card 3


What are the issues when classifying and diagnosing SZ?


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Card 4


What is reliability?


Preview of the front of card 4

Card 5


How can reliability be assessed?


Preview of the front of card 5
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