Reliability and validity in diagnosis and classification Flashcards
What is reliability for Sz
Diagnosis must be repeatable
What is test retest reliability for Sz
The same clinitian must reach the same conclusion at different points in time
What is inter-rater reliability for Sz
Different clinitians must reach the same conclusion
What is a good kappa score for reliability of diagnosis
0.7
Why might there be cultural differences in diagnosis of Sz
-Copeland gave 134 US and 194 British psychologists a description of a patient. 69% of the US ones said they had Sz while only 2% of British did
-Luhrmann interviewed 60 adults diagnosed with Sz 20 from Ghana, 20 from India and 20 from the US. The African and Indian subjects often heard positive advice from their voices while the Americans did not
Who checked the inter rater reliability of US and British psychologists
Copeland
Who found african and indians heard nice voiced
Luhrmann
Why may gender bias threaten the validity of Sz diagnosis
Gender biased diagnostic criteria or clinitians may lead to judgements being based on seriotypes of a gender. Rotherman found women were less likely to be diagnosed because their abnormal behaviour was more likely to be ignored
Why is symptom overlap an issue for validity of diagnosis
Many Sz symptoms are found in other disorders, with Ellason and Ross pointing out that people with Dissociative Identity Disorder (DID) actually have more Sz symptoms than those with Sz
Who found women were naturally sorta insane so less likely to be diagnosed
Rotherman
Whoclaimed those with DID had more symptoms of Sz than those with Sz
Ellason and Ross
What is co-morbidity
When two or more conditions co-occur
Why is comorbidity an issue for validity of Sz diagnosis
Co-morbidities are common among those with Sz, with Buckley estimating that co-morbid depression occurs in 50% of patients, and 47% also having a lifetime diagnosis of co-morbid substance abuse
Who found lots of comorbidity with Sz patients
Buckley et al
How is lack of inter-rater reliability an issue for diagnosing Sz (eval)
Over the last 30 years there has been little evidence that the DSM is routinely used with high reliability. Whaley found inter-rater reliability correlations as low as 0.11. Rosenhans ‘sane in insane places’ also show poor inter rater reliability with the fact that some pseudopatients were released and others weren’t
Who found inter-rater reliability of 0.11
Whaley
Who did ‘sane in insane places’
Rosenhan
What is a real world difference with culutral differences in diagnosis of Sz (eval)
The ethnic culture hypothesis suggests that ethnic minority groups experience less distress associated with Sz because of the protective characteristics and social structures that exist within these cultures. Brekke and Barrio found evidence to support this hypothesis in a study of 184 Sz sufferers. Those in minority groups were less symptomatic than those not in these groups
Who found minorities are less symptomatic than the majority
Brekke and Barrio
What is research support for the issues of gender bias in diagnosis (eval)
Loring and Powell randomly selected 290 male and female psychologists to read two cases of patient behaviour. If the patient was described as ‘male’ or no gender was given, 56% gave a diagnosis of Sz. If the patient was female, 20% gave a diagnosis. This difference wasn’t present in female psychologists
Who found evidence of gender differences in diagnosis
Loring and Powell
How does prognosis of patients impact validity of diagnosis (eval)
There is no evidence that those diagnosed with Sz share the same outcomes. Only 20% recover to their previous levels and about 30% show improvement. A diagnosis of Sz therefore has little predictive validity. Gender and psychological factors do seeom to influence recovery
How does prognosis of patients impact validity of diagnosis (eval)
There is no evidence that those diagnosed with Sz share the same outcomes. Only 20% recover to their previous levels and about 30% show improvement. A diagnosis of Sz therefore has little predictive validity. Gender and psychological factors do seeom to influence recovery
