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Reliability and validity
What is reliability in schizophrenia?
Means the consistency of diagnosis
Reliability and validity
What is diagnostic reliability?
Test-retest: same clinician, same conclusion, two different points in time (eg: original diagnosis, and when watching a recording)
Inter-rater reliability: different clinicians, same conclusions
Reliability and validity
What is a kappa score?
measures inter-rater reliability
1 perfect agreement, 0 zero agreement
0.7 or above is considered good
Regier et a (2013): DSM-V’s 0.46 kappa score for schizophrenia (moderate)
Reliability and validity
Reliability: what is cultural difference in diagnosis, and what does this indicate?
Cultural differences:
Significant variation between countries in diagnosing schizophrenia,
Indicates that:
Culture influences the diagnostic process
Reliability and validity
(Can be Evaluation): Reliability: examples of cultural differences in diagnosis → inter-rater reliability
Copeland et al (1971):
69% of the US psychiatrists diagnosed with schizophrenia vs 2% of British based on same description + same classification system (DSM-V) (low cross cultural inter-rater reliability)
Suggests reliability can be consistent within, but inconsistent between cultures (so cultural variations impact reliability
Reliability and validity
(Can be Evaluation): Reliability: examples of cultural differences in diagnosis → symptom variance
Luhrmann et al (2015):
Interviewed adults (20 Ghanian, 20 Indian, 20 American)
Many African + Indian Ps reported positive experiences w/ voices BUT US patients violent/distressing voices
This suggests manifestation of symptoms vary culturally, + using one universal classification tool (imposed etic) would result in inconsistent, and so less reliable, diagnoses due to the variance in symptoms.
Can be overcome by using an emic approach (eg: indigenous classification systems)
Reliability and validity
Rosenhan (1973) (part 1):
8 pseudo patients, w/ fake name/job/one symptom (unfamiliar voice that said ‘hollow’, ‘empty’, ‘thud’) everything else said was real)
Recorded treatment + operation of ward
After admission - told staff they felt ‘fine’ and symptom was gone
NO Ps detected as not having schizophrenia by staff
Normal behaviour seen as symptoms → similar to real patients (eg: waiting outside of cafeteria = 'oral-accusative syndrome', NOT boredom)
Were in hospital b/ 1-7 weeks - discharged w/ 'schizophrenia in remission), BUT some other patients suspected they were sane (35/118 patients voiced this)
Reliability and validity
Rosenhan (1973) (part 2):
Told institutions pseudo-patients were being admitted (none were) and people were falsely accused of being one
suggests → Diagnosis label = schema
INSTEAD should focus on individual's specific behaviours + problems
Reliability and validity
What does Rosenhan (1973) tell us about the problems of reliability of diagnosis?
LACKS reliability:
Definitions need to be more operationalised, rigid, and structures
Demonstrates psychiatrists cannot reliably tell the difference b/w sane and insane people
COUNTER-POINT:
Invalid - admitted when they didn't have schizophrenia but pretend they did - hospitals are more likely to say 'better safe than sorry' (not discharge someone who isn't ready)
Reliability and validity
What is validity in schizophrenia?
The extent to which a diagnosis represents the disorder it is measuring, that is distinct from other disorders
Reliability and validity
Validity: what is gender bias in diagnosis?
Clinicians can base judgements of diagnosis on stereotypical beliefs about gender
Eg: Boverman et al (1970) → women less likely to be diagnosed than men
In USA, definitions of a mentally healthy adult = a mentally healthy male (androcentric) → led people to believe women = less healthy bcs deviate (from 'male' behaviour) BUT may be bcs differences in help-seeking behaviour → measuring gender behaviours NOT disorder
Reliability and validity
Validity: what is symptom overlap? What is the issue with it?
ICD and DSM have been known to be unsuccessful when it comes to differentiating between symptoms of S and other disorders
This lack of distinction calls into question validity of classification/diagnosis of S, + if S = UNIQUE disorder, or if S/DID/Bipolar = part of the same branch of disorder
Reliability and validity
Validity: examples of symptom overlap
Ellson and Ross (1995):
People w/ DID have more S symptoms than people diagnosed w/ S
both have positive and negative symptoms
Read (2004):
most people with schizophrenia have sufficient symptoms to receive at least one other diagnosis (Eg: bipolar disorder shares positive symptoms like delusions, + negative symptoms like avolition.
Reliability and validity
Validity: what is co-morbidity?
when two conditions co-occur - common in schizophrenic patients
50% have depression
12% have OCD
Reliability and validity
What does Rosenhan (1973) tell us about the problems of validity of diagnosis?
They weren’t able to recognise what disorder it was
Behaviour was often misinterpreted in terms of diagnosis (eg: patients waiting for lunch)
SUGGESTING definition of schizophrenia is not clear enough
Reliability and validity
Evaluation: diagnosis has low reliability
diagnosis has low reliability, (consistency of a study) If a study = inconsistent → lack reliability. Reiger et al (2013): DSM-V's S kappa score = 0.46, suggesting low reliability → inconsistency b/w mental health professionals = limitation of the diagnosis → suggests DSM-V = invalid
Reliability and validity
Evaluation: diagnosis has low validity
Limitation of diagnosis = low validity → standard assessment = is criterion validity (do different assessments systems give same diagnosis for same patient?) → Ellason + Ross (1995) found people w/ DID have more S symptoms than people diagnosed as S → questions if schizophrenia is a UNIQUE disorder, or if schizophrenia/DID/Bipolar are part of the same branch of disorder
Reliability and validity
Evaluation: symptom variations = issue w/ validity
two people w/ S diagnosis can share NO SYMPTOMS w/ each other → questions validity of classification tools in accurately representing/describing the disorders it attempts to
Reliability and validity
Evaluation: Gender bias
Longnecker et al (2010)'s meta-analysis of schizophrenia prevalence found men are diagnosed more often than women since the 1980s, so gender bias means that people with similar symptoms are receiving different diagnosis's
Reliability and validity
Evaluation: Culture bias
People of African origin are more likely to be diagnosed w/ schizophrenia in the UK, and rates are lower in Africa/West Indies - so not bcs of genetics, but rather bcs of culture bias meaning symptoms in the UK, but considered 'normal' in African cultures (eg: AVH) - issue w/ validity