Evaluation of reliability for diagnosis of Schizophrenia

Question 1

A03 - Evidence against?

Answer 1

P - There is supporting evidence that there are issues with inter rater reliability in the diagnosis of SZ.

E - This comes from Copeland who found that 69% of the US psychiatricts diagnosed the patient with SZ, where as 2% of the UK were diagnosed.

E - Therefore there is no consistency in the diagnosis criteria and the DSM is clearly flawed as it would seem that diagnosis depends on whether factors such as the country you live in.

• Issues with inter rater reliability
• Copeland
• 69%
• UK
• US
• 2%

Question 2

A03 - Evidence that questions…

Answer 2

P - There is evidence that questions the test - retest reliability (external reliability)

E - Read (2004) reported the test analysis is as low as 37% for sz which is concerning, especially when we consider the potential false positives/negatives this could result in.

E - This shows that this certain diagnosis method is faulty and is difficult to diagnose SZ for certain.

L - This shows the lack of reliability toward the test in diagnosing SZ, and the negative implications.

• Test - retest reliability (external reliability)
• Read (2004)
• 37%

Question 3

A03 - Supporting research for improvment?

Answer 3

P - However, there is supporting research that shows low diagnosis of SZ can greatly be improved with certain methods.

E - Farmer et al (1988) found that a standardised interview technique (present state examinations) (PSE) increases reliability of diagnosing SZ because it focuses on the frequancy and severity of symptoms. This means all patients are asked these things.

E - This means all patients have the same diagnosis process of SZ.

L - Thus, all patients have a better chance of being diagnosed/not correctly, increasing reliabilty.

• Improved
• Farmer et al (1988)
• standardised interview technique
• severity of SZ

Question 4

A03 - Improvment of DSM

Answer 4

P - The DSM has also now improved the reliability of diganosis through revising the criteria.

E - For example, the DSM V has now stripped the criteria from the diagnostic guide as it was difficult to differentiate between bizzarre (an impossible) delusion and non-bizzarre (possible) delusions.

L - This means less false positives/negatives meaning higher reliability in diagnosis. Thanks to the more advanced criteria methods.

• DSM
• Bizzarre
• non - Bizzarre