Reliability & Validity

Question 1

How should classification and diagnosis of schizophrenia be?

Answer 1

• Relatively easy - use a ‘checklist’ that reduces the problem of misdiagnosis
• However isn’t always easy - clinician’s subjective opinion
• Different too objective methods used in medicine e.g. diagnosing diabetes by testing blood-glucose level

Question 2

What is reliability?

Answer 2

• Consistency of symptom measurement across clinicians
• Affects diagnosis in 2 ways:
  1) Test-retest reliability = extent the same clinician makes same diagnosis with same info
  2) Inter-rater reliability = extent different clinicians agree on same diagnosis
• Measured by Kappa score, 1 = perfect inter-rater agreement, 0 = no agreement, 0.7+ = generally ‘reliable’