Reliability And Validity In Classification And Diagnosis

Question 1

What does diagnostic reliability mean?

Answer 1

• that a diagnosis of schizophrenia 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 2

Reliability: What does research suggest about variation between countries when it comes to diagnosing schizophrenia?

Answer 2

• culture has an influence on the diagnostic process

Question 3

Reliability: How has Copeland tested the reliability of the diagnosis of schizophrenia?

Answer 3

• Gave 134 US and 194 British psychiatrists a description of a patient.
• 69% of the US psychiatrists diagnosed the patient with schizophrenia but only 2% of the British psychiatrists did.

Question 4

Reliability: How has the characteristic ‘hearing voices’ been investigated by psychologists?

Answer 4

• Luhrmann et al: Interviewed 60 adults diagnosed with schizophrenia
• 20 each in Ghana, India and the US
• They were asked about the voices that they heard
• Many of the African/Indian subjects reported positive experiences with their voices, describing them as playful or offering advice, not one American did.
• US subjects more likely to report the voices they heard as being violent and hateful.

Question 5

Validity: How has gender bias affected the validity of the classification and diagnosis of schizophrenia?

Answer 5

• gender-biased diagnostic criteria or clinicians basing their judgements on stereotypical beliefs held about gender.
• these reduce the accuracy of diagnostic judgements.

Question 6

Validity: What have researchers found about the effect of gender bias on the classification and diagnosis of schizophrenia?

Answer 6

• Broverman et all: Clinicians in the US equated mentally healthy ‘adult’ behaviour with mentally healthy ‘male’ behaviour.
• As a result, there was a tendency for women to be perceived as less mentally healthy.

Question 7

Validity: How has symptom overlap affected the validity of the classification and diagnosis of schizophrenia?

Answer 7

• there is considerable overlap between the symptoms of schizophrenia and symptoms of other conditions (like bipolar disorder).
• they both involve positive symptoms (delusions) and negative symptoms (avolition).
• suggests that they may not be two different conditions, but variations of a single condition.
• means that schizophrenia is hard to distinguish from bipolar disorder.

Question 8

Validity: What is co-morbidity?

Answer 8

• the occurrence of two disorders or conditions together.

Question 9

Validity: How has co-morbidity challenged the validity of the diagnosis of schizophrenia?

Answer 9

• If conditions occur together a lot of the time, then the validity of their diagnosis is questioned because they might actually be a single condition.
• Schizophrenia is commonly diagnosed with other conditions. For example, one review found that about half of those diagnosed with schizophrenia also had a diagnosis of depression or substance abuse.
• Means that schizophrenia may not actually exist as a distinct condition.
• Can lead to wrongful diagnosis.

Question 10

Evaluation: Good Reliability

Answer 10

• Strength of the diagnosis of schizophrenia = reliability
• Research supports excellent reliability for the diagnosis of schizophrenia in 180 individuals using the DSM-5.
• Pairs of interviewers achieved inter-rather reliability of =.97 and test-retest reliability of +.92.

Question 11

Evaluation: Low Validity

Answer 11

• Cheniaux et al: Had 2 psychiatrists independently rate the same 100 clients using the ICD-10 and the DSM-5 criteria.
• ICD: 68 diagnosed with schizophrenia
• DSM: 39 diagnosed with schizophrenia.
• Suggests that schizophrenia is either over or under diagnosed according to the diagnostic system.
• Low criterion validity.