Evaluating Diagnosis

• what is reliability?

  the extent in which clinicians agree on a disorder after independently accessing a patient.
• inter-rater reliability


  what reliability means in relation to clinicians diagnosis of SZ.
• test-retest reliability


  measured on 'Kappa score'
• Kappa score


  Provides standardised method of recognising diagnosis, improving reliability.
• what happens to reliability as classifications are published?

  improves
• why is diagnosis reliable?

  fiels trails show levels of agreement between clinicians.
• Reiger and linking to reliability


  3 disorders had Kappa value of 0.60 to 0.70 while 7, including SZ, had value 0.40 to 0.59.

  Reliable as can be replicated & make consistent diagnosis.
• What opposes the idea of Reiger & diagnostic reliability?


  Over time levels of agreement change, therefore reliability is questioned.
• What makes diagnosis unreliable?

  DSM-V not reliable for all disorders.
• Cooper and Reigner & unreliability


  DSM task force classified values 0.2 to 0.4 'acceptable' & Reigner found poor reliability score for MDD.

  Less reliable than previous versions & room for diagnostic error.
• Kupfer & Kraemer opposing unreliability


  argue clinicians were asked to mirror normal DSM-5 field trials. In contrast, DSM-3 used carefully screen 'test' client & clinicians were given detailed training.

  Therefore reliability varies as do the results of the study.
• predictive validity

  extent of which diagnosis accurately predicts development and prognosis of a disorder.
• concurrent validity


  degree to which it corresponds to external criteria that is pre-existing.
• what makes diagnosis valid?

  operationalisation of symptoms that make up the mental disorder.
• comorbidity

  presence of one or more additional disorders co-occuring with the primary disorder.
• How is comorbidity common in SZ?

  usually have anxiety and depression.

  estimated prevelence of 15% having panic anxiety & 23% OCD.
• Why does Comorbidity reduce validity?

  comorbidity & symptons overlap reducing validity.
• What makes diagnosis valid?

  If a disorder has high predictive validity then it is desirable as development is clear.
• Evidence of predictive validity

  5 year olds with conduct disorder were more likely to show behavioural & educational difficulties by 7.
• What does Mason say?


  showed predicative validity within ICD's diagnosis of SZ regarding future disabilities.
• How does Bleuer oppose validity?


  20% full recovery & 40% continued in a psychotic state.

  --> cannot fully predict how SZ develops & contradicts predictive validity figures.