Reliability and validity in diagnosing and classification

what is diagnostic reliability?

means that a diagnosis of Sz must be the repeatable, clinicians must be able to reach the same conclusions through test-retest reliability

what is co-morbidity?

refers to the extent that 2 (or more) conditions or diseases occur simultaneously in a patient, for example Sz and depression

what is culture?

the rules customs morals, child rearing practices etc that bind a group of people together and define how they are likely to behave

what is gender bias?

refers to the tendency to describe the behaviour if men and women in psychological theory and research in such a way that might not be seen to represent accurately of either one of these genders

what is reliability

consistency of measurements

what is symptom overlap?

refers to the fact that symptoms of the disorder may not be unique to that disorder but may also be found in other disorders, making accurate diagnosis difficult

what is validity

refers to whether an observer effect is a genuine one

what is the problem with reliability when diagnosing Sz?

the cultural differences in diagnosis

who did an experiment on reliability for diagnosing Sz?

• Copeland

• Luhrmann

what was the number of pps in Copeland study?

• 134 US pps

• 194 British psychiatrists

what did Copeland give his pps

a description of a patient

what were the results of Copeland study?

• 69% of US psychiatrists diagnosed Sz

• 2% of the British psychiatrists gave the same diagnosis

what is one of the main characteristics of Sz that appears to be influence by cultural environment?

hearing voices

who carried out interviews on adults diagnosed with Sz?

Luhrmann

how many people were in Luhrmann’s study?

• 60 adults

• 20 in Ghana, india and US

what was the interview conducted by Luhrmann on?

asked about hearing voices

what were the results of Luhrmann’s study?

• African and indian subjects reported positive experiences with their voices

• not one American experience a positive experience

how did African and indian pps report their voices?

playful and offering advice

how did American pps report their voices?

violent and hateful

what did Luhrmann conclude?

the ‘harsh’ and ‘violent’ voices so common in the West may not be an inevitable feature of Sz

what’s are the problems with validity for diagnosing Sz?

• gender bias

• symptom overlap

• co-morbidity

when does gender bias in diagnosing Sz occur?

when accuracy of diagnosis is dependent on the gender of an individual

what are the reasons for accuracy of diagnostic judgements varying?

• gender biased diagnostic criteria

• clinicians basing their judgements on stereotypical beliefs held about gender

what’s an example of clinical gender bias?

critics of the DSM diagnostic criteria argue that some diagnostic categories are biased towards pathologising one gender rather than the other

what was Broverman’s finding?

found that clinicians in the US equated mentally healthy adult behaviour with mentally healthy ‘male’ behaviour

what was the conclusion of Broverman study?

there was a tendency for women to be perceived as less mentally healthy

what did Ellason and Ross find?

pointed out that people with dissociative identity disorder (DID) actually have more Sz symptoms than people diagnosed as being Sz

What percentage did Buckley estimate that co-morbid depression occurs?

50%

What percentage of patients did Buckley find who had a lifetime diagnosis of co-morbid substance abuse?

47%

what % of the population have Sz?

1%

what % of people did Swet find who had Sz and OCD?

12%

what was rosenhan’s study?

to investigate how situational factors affect a diagnosis of Sz

how many confederates were in Rosenhan’s study?

8 confederates acted as pseudo patients

how many hospitals did the confederates go to?

12 different hospitals

what did they pseudo patients say to the pp doctors?

they complained of hearting voices saying ‘empty’, ‘hollow’ and ‘thud’. they said that the voices were unclear unfamiliar and of the same sex as them

what did the confeds do when they entered the ward?

stoped pretending symptoms and behaved normally

when were the confeds discharged?

when they convinced staff that they were sane

what were the results of Rosenhann’s first study?

• staff diagnosed 11 pseudo patients with Sz

• 1 with manic-depression

• never detected their sanity sayings their behaviour showed ‘no abnormal indications’

what was the average hospital stay in Rosenhan’s study?

19 days

what was the conclusion of Rosenhan’s first study?

psychiatrists can’t reliably tell the difference between an insane and sane person calling into question the reliability of a Sz diagnosis

what was the follow up experiment?

pps were staff in a teaching and research hospital. Staff had been told that at some time one or more pseudo-patients would attempt to be admitted to the hospital

how long did the follow up study last for?

3 months

what were pps asked to do in the follow up study?

rate the likelihood that this person was a pseudo patient on a scale of 1-10

how many pseudo-patients were in the follow up study?

none

how many patients were judged?

193

what were the results of the follow up study?

• 41 we’re confidentially judged to be pseudo patients by at least one staff member

• 23 were suspected by at leats one psychiatrist

• 19 were suspected by a psychiatrist and staff member

what % of patients were confidently identified as pseudo patients?

21%

what was the question asked by the pseudo patient in the mimi experiment?

pardon me, Mr/Mrs/Dr.X, could you tell me when I will be presented at the staff meeting? or when am I likely to be discharged?

what was the control measure of the mini experiment?

a record was also kept of a young lady approaching staff member son a Uni campus and asking them 6 questions

what was the results of the controlled measure in the mini experiment?

• all staff members stripped and answered all the 6 questions

• respondents maintained eye contact with the questioner

what was the results of the pseudo-patient group in the mini experiment?

only 4% of the psychiatrists and even fewer nurses stopped and answered the question posed by the pseudo patient and most continued without pausing

whats the DSM V?

American diagnostic statistical manual for diagnosing mental disorders

what things do you have to have in order to be diagnosed with Sz according to the DSM V?

• The person must have at least two of these symptoms for 1 month, and one must be from the first three:

  • Delusions (false beliefs, like paranoia).

  • Hallucinations (e.g., hearing voices).

  • Disorganized speech (confused or jumbled talking).

  • Disorganized or catatonic behavior (odd actions or lack of movement).

  • Negative symptoms (e.g., lack of emotion or motivation).

• significant impairment for 6 months

whats the ICD 10?

International Classification of Diseases, 10th Edition is another system used to diagnose schizophrenia, primarily outside the UK

what does the ICD specify you have to have in order to be diagnosed with Sz?

At least one of these key symptoms must be present most of the time for 1 month or more:

• Delusions of control: Believing thoughts, feelings, or actions are being controlled by an external force.

• Auditory hallucinations: Voices commenting, discussing, or giving commands.

• Persistent delusions: Unreal beliefs that are culturally inappropriate and implausible (e.g., being a god).

Alternatively, two or more of the following must be present for 1 month or more:

• Hallucinations

• Disorganized speech

• Catatonic behavior:

• Negative symptoms:

• Behavioral changes: