Reliability & Validity in Diagnosis

Question 1

What is reliability?

Answer 1

Whether a diagnosis of schizophrenia is repeatable.

Question 2

What are the 2 ways reliability can be measured?

Answer 2

• Inter-rater reliability - whether 2 clinicians give identical diagnoses of same patient
• Test-retest reliability - whether tests used/clinicians are consistent over time in giving the same diagnosis on separate occasions using the same info

Question 3

What is validity?

Answer 3

• The extent that a diagnosis is distinct from other disorders.
• The extent that a classification system measures what it claims to measure.

Question 4

What are the 3 ways of assessing validity?

Answer 4

• Predictive validity - if diagnosis leads to successful treatment then it’s valid
• Descriptive validity - patients’ symptoms should differ from patients with other disorders
• Aetiological validity - all schizophrenics should have same cause for disorder (aetiology = cause)

Question 5

What is co-morbidity?

Answer 5

The extent that 1 or more additional disorders occur simultaneously with schizophrenia.

Research found 50% of schizophrenics also have depression & 47% have substance abuse.

Question 6

What is symptom overlap?

Answer 6

The extent that symptoms of
schizophrenia can also be found in other disorders.

Research found people with dissociative identity disorder have more symptoms of schizophrenia than people actually diagnosed with it.

Question 7

What is culture bias?

Answer 7

• Tendency to over diagnose people from other cultures with schizophrenia.

Research found black Afro-Caribbean groups 8 times more likely to be diagnosed than white groups.

Question 8

What is gender bias?

Answer 8

• Tendency for diagnostic criteria to be applied differently to males & females.
• Ignoring differences between men and women potentially leading to higher diagnosis in women

Hormone estradiol effective in treating women with Sz - suggests different vulnerability factor in women which needs
to be considered