Sc - Reliability and validity in diagnosis and classification

Question 1

Co-morbidity

Answer 1

Refers to the extent that two (or more) conditions or diseases occur simultaneously in a patient, for example sz and depression.

Question 2

Culture

Answer 2

The rules, customs, morals, childrearing practices, etc. that bind a group of people together and define how they are likely to behave.

Question 3

Gender bias

Answer 3

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

Question 4

Reliability

Answer 4

Is consistency - the consistency of measurements. We would expect any measurement to produce the same data if taken on successive occasions.

Question 5

Symptom overlap

Answer 5

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

Question 6

Validity

Answer 6

Refers to whether an observed effect is a genuine one.

Question 7

What does diagnostic reliability mean in sz?

Answer 7

Means that the diagnosis of sz must be repeatable, i.e. clinicians must be able to reach the same conclusions at two different points in time (test-retest reliability), or different clinicians must reach the same conclusions (inter-rater reliability).

Question 8

What is test-retest reliability?

Answer 8

Clinicians must be able to reach the same conclusions at two different points in time.

Question 9

What is inter-rater reliability?

Answer 9

Different clinicians must reach the same conclusions.

Question 10

What is inter-rater reliability measured by?

Answer 10

A statistic called a kappa score.

Question 11

Explain how kappa scores work

Answer 11

Used to measure inter-rater reliability.

A score of 1 indicates perfect inter-rater agreement; a score of 0 indicates zero agreement.

A kappa score of 0.7 or above is generally considered good.

Question 12

What is the kappa score for the diagnosis of SZ in the DSM-V field trials?

Answer 12

0.46 (Regier et al., 2013).

Question 13

What factor is talked about when discussing the reliability of classification/diagnosis?

Answer 13

Cultural differences.

Question 14

What factors are talked about when discussing the validity of classification/diagnosis?

Answer 14

Gender bias, symptom overlap and co-morbidity.

Question 15

Explain how there is cultural bias in diagnosis of SZ

Answer 15

• Copeland (1971) gave 134 US and 194 British psychiatrists a description of a patient. 69% of the US psychiatrists diagnosed SZ, but only 2% of the British ones gave the same diagnosis.
• ‘Hearing voices’ as a symptom appears to be influenced by cultural environment - Luhrmann et al. (2015) interviewed 60 adults with SZ (20 each in Ghana, India and the US). Each was asked about the voices they heard - many of the African and Indian subjects reported positive experiences with their voices (describing them as playful or as offering advice) but none of the Americans did. The US subjects were more likely to report them as violent and hateful (and indicative of being ‘sick’). Luhrmann suggests that the ‘harsh, violent voices so common in the West may not be an inevitable feature of SZ’.

Question 16

Explain how there is gender bias in diagnosis of SZ

Answer 16

• Said to occur when the accuracy of diagnosis is dependent on the gender of an individual.
• The accuracy of diagnostic judgements can vary for a number of reasons, including gender-biased diagnostic criteria or clinicians basing their judgements on stereotypical beliefs held about gender.
• For example, critics of the DSM diagnostic criteria argue that some categories are biased towards pathologising one gender rather than the other.
• Broverman et al. (1970) found that clinicians in the US equated mentally healthy ‘adult’ behaviour with mentally healthy ‘male’ behaviour. As a result, there was tendency for women to be perceived as less mentally healthy.

Question 17

Explain how symptom overlap affects the validity of SZ diagnosis/classification

Answer 17

• Many positive and negative symptoms of SZ are also found in many different disorders, such as depression and bipolar disorder.
• Ellason and Ross (1995) point out that people with dissociative identity disorder (DID) actually have more schizophrenic symptoms than people diagnosed as being schizophrenic!
• Most people who are diagnosed with SZ have sufficient symptoms of other disorders that they could also receive at least one other diagnosis (Read, 2004).

Question 18

Explain how co-morbidity affects the validity of SZ diagnosis/classification

Answer 18

• Including substance abuse, anxiety and symptoms of depression,
• Buckley et al. (2009) estimate that co-morbid depression occurs in 50% of patients, and 47% of patients also have a lifetime diagnosis of co-morbid substance abuse.
• SZ and OCD are 2 distinct psychiatric conditions. Roughly 1% of the population develop SZ, and roughly 2-3% develop OCD. Despite both being fairly uncommon, evidence suggests that the two conditions appear together more often than chance would suggest. A meta-analysis by Swets et al. (2014) found that at least 12% of patients with SZ also fulfilled the diagnostic criteria for OCD and about 25% displayed significant obsessive-compulsive symptoms.

Question 19

What is the key study for the reliability and validity in diagnosis and classification of SZ?

Answer 19

On being sane in insane places.

Question 20

What did the on being sane in insane places study highlight?

Answer 20

The unreliability of diagnosis.

Question 21

Who did the on being sane in insane places study?

Answer 21

Rosenhan (1973)

Question 22

Explain the on being sane in insane places study

Answer 22

‘Normal’ people presented themselves to psychiatric hospitals in the US claiming they heard an unfamiliar voice in their head saying the words ‘empty’, ‘hollow’ and ‘thud’.

They were all diagnosed as having SZ and admitted. Throughout their stay, none of the staff recognised that they were not actually displaying symptoms of SZ.

In a follow-up study, Rosenhan warned hospitals of his intention to send out more ‘pseudopatients’. This resulted in a 21% detection rate, although non actually presented themselves!