reliability and validity in diagnosis and classification

Question 1

validity

Answer 1

refers to the accuracy of diagnosis and classification

one way to assess validity of diagnosis is criterion validity, so different assessment systems (icd-10 and dsm-5) arrive at the same diagnosis for the same patient

Question 2

reliability

Answer 2

refers to consistency in diagnosis and classification

means that clinicians must be able to diagnose schizophrenia at two different points in time (rest-retest reliability) or different clinicians must be able to reach the same conclusions (inter-rater reliability)

Question 3

factors affecting validity

Answer 3

symptom overlap

co-morbidity

gender bias

Question 4

symptom overlap

Answer 4

means symptoms shown in schizophrenia can overlap with other mental health disorders, making diagnosis inaccurate

e.g. symptoms such as auditory hallucinations can occur in disorders such as bipolar depression as well as schizophrenia, therefore an invalid diagnosis is possible because psychiatrists cannot be 100% certain symptoms shown are that of schizophrenia

Question 5

co-morbidity

Answer 5

this refers to two or more mental health disorders occurring at the same time; meaning symptoms of both disorders are present

this means that symptoms cannot be used to make a valid diagnosis for schizophrenia, making validity weak

e.g. schizophrenia and depression

Question 6

gender bias

Answer 6

occurs when accuracy of diagnosis is dependent on gender of person being examined

means that psychiatrist may be biased towards diagnosing one gender rather than the other, which means diagnosis may not be accurate

Question 7

evidence for system overlap

Answer 7

strong research

konstantareas & hewitt

found that when comparing 14 autistic patients with 14 schizophrenics, 7 of the autistic patients also showed symptoms of schizophrenia (e.g. no emotions or flat emotions)

suggests that diagnosis of schizophrenia may not always be valid because the person may exhibit a symptom typical of schizophrenia but could instead have another condition with the same symptom

Question 8

evidence for gender bias

Answer 8

strong research evidence

loring and powell (1988)

found that 50% of psychiatrists gave a diagnosis when patient was described as a male, but only 20% diagnosed when described as a female

this suggests the diagnosis may be invalid as it is dependent on the gender of the patient

Question 9

rosenhan procedure

Answer 9

1973

8 volunteers who didn’t suffer from mental illness attempted to gain admission into different psychiatric hospitals in america, claiming to hear voices saying “thud”

they were all admitted then acted normally

time taken to be released from hospital and psychiatrists reactions towards the patients were recorded

later, one hospital was informed that an unspecified number of pseudo-patients would attempt to be admitted into the hospital over the next 3 months

number of suspected imposters was recorded

Question 10

rosenhan findings

Answer 10

8 volunteers took between 7 -52 days to be released from hospital (avg 19)

patients were diagnosed with schizophrenia and being in remission

normal behaviours shown by patients whilst in hospital were interpreted as symptoms

during 3 month period, 193 patients were admitted to hospital, 83 were recorded as imposters but no pseudo-patients attempted admission

Question 11

rosenhan conclusion

Answer 11

diagnosis lacks validity as psychiatrists cannot distinguish between real and pseudo-patients

rosenhan states that psychiatric labels tend to stick and everything the patient does is interpreted in relation to the diagnostic label that has been applied to them

Question 12

rosenhan peel

Answer 12

there is research to suggest diagnosis of schizophrenia leads to labelling

rosenhan 1973

found that label of schizophrenia can be difficult to remove and affects other people’s attitudes towards you.

rosenhan’s research demonstrated that even when an invalid diagnosis is given, all the behaviours shown by the patient are interpreted as symptoms of schizophrenia

suggests the diagnosis of schizophrenia has long lasting, negative effects on social relationships, work prospects and self-esteem. this seems especially unfair when diagnosis is not always valid

Question 13

eval of rosenhan

Answer 13

limit is that it is historically biased

which is when a piece of research doesn’t have the ability for its findings to be generalised over time, decreasing external valdidity

this is because the study was performed in 1973; when the quality of care in mental health institutes was poor.

rosenhan’s study actually helped to encourage reform, and diagnosis improved dramatically

this suggests that if Rosenhan’s study was replicated today, the same results might not be achieved as the validity of diagnosis has improved since the 1970s

Question 14

factors affecting reliability

Answer 14

cultural bias

Question 15

cultural bias

Answer 15

the tendency for people to judge the world through a narrow view based on their own culture

affects reliability as patients will get a different diagnosis from different psychologists, depending on whether the psychiatrist understands their cultural beliefs, therefore diagnosis is not consistent

e.g. if people of african-caribbean descent are diagnosed by a british psychiatrist they are much more likely to be diagnosed with schizophrenia (as cultural beliefs are mistaken for symptoms)

Question 16

evidence for cultural bias

Answer 16

strong research evidence suggesting cultural bias can lead to inconsistencies in diagnosis of schizophrenia

which is when a theory, model or explanation inappropriately judges behaviour from European or North American cultural norms

e.g. Copeland (1971) gave 134 US and 194 british psychiatrists a description of a patient, 69% US psychiatrists diagnosed schizophrenia, but only 2% of British gave diagnosis

this suggests diagnosis is dependent on psychiatrist having an accurate understanding of patient’s cultural background, which isn’t likely to always be the case, reinforcing that diagnosis is not always going to be consistent.

Question 17

evidence for reliability issues being evidence (+)

Answer 17

strong research suggesting diagnosis is inconsistent between different psychiatrists

mojtabi and nicholson (1995)

asked 50 psychiatrists to differentiate between ‘bizarre’ and ‘non-bizarre’ delusions, as patients only need one other symptom if their delusions are ‘bizarre’

the inter-rate reliability co-efficient was only 0.4, when this should be 0.8 or above

suggests that inconsistencies between psychiatrists do exist, weakening the reliability of the diagnosis of schizophrenia