Reliability and Validity

Question 1

Reliability

Answer 1

• Refers to whether the same set of symptoms would get the same diagnosis from different psychiatrists
• Due to the same symptoms occur over several different disorders, and therefore psychiatrists may diagnose a different disorder, so the diagnosis is unreliable
• A diagnosis is reliable if the diagnosis is consistent over two different time period for the same patient using the same psychiatrist
• Reliability is improved by the new improved version of the DSM

Question 2

Inter rater reliability

Answer 2

• Reliability between raters
• Multiple people use the same manual on the same patient to diagnose the disorder
• If the rating are consistent the reliability is high

Question 3

Test retest reliability

Answer 3

• Reliability between trials
• If the patients consistently get the same diagnosis over time
• If the rating are consistent the reliability is high

Question 4

Strength of Reliability

Answer 4

• One strength is that Brown et al did research on the DSM 4. It found that the DSM 4 has excellent reliability scores for numerous mental health disorders
• The inter rater reliability for specific phobias are 0.7 and for OCD it was 0.75. It is seen that any score over 0.7 is considered good
• Therefore this suggest that the DSM is a reliable diagnostic tool that can consistently identity mental health disorders

Question 5

Weakness of Reliability

Answer 5

• One weakness is that Beck et al did research on the diagnostic manuals
• A series 153 patients were examined independently by a paired psychologist and diagnosis were made independently according the manuals at the time, the degree of agreement was 54%. - This is due to unclear criteria for diagnosis and inconsistency in techniques to gather data, suggesting that the vagueness of early manuals lead to many misdiagnoses and subsequent ineffective treatments

Question 6

Validity

Answer 6

• If two different diagnosis systems agree about the symptoms of mental health disorders
• A valid diagnosis system will operationalise the symptoms and behaviour that make up the disorder
• If the diagnosis leads to a treatment and can be used to predict how the treatment will work, it had predictive validity
• A valid diagnostic tool should be able to identity the causes of mental health disorder

Question 7

Concurrent validity

Answer 7

• Comparing evidence from multiple sources to check agreement
• ICD and DSM

Question 8

Aetiological Validity

Answer 8

• Examining the causes of the disorder and matching the to the person’s history
• Such as factors that can lead to depression can be trauma, genes and stress and finding the causes of the factors
• If the cause fit the person’s diagnosis there is validity

Question 9

Predicitive validity

Answer 9

• Whether the diagnosis can predict future behaviour
• Such as if someone has a intense fear of gaining weight, we can predict at some point they may have a lower BMI in context of age, sex and trajectory development

Question 10

Strength of Validity

Answer 10

• One strength is the there is evidence that the ICD and DSM have predictive validity
• Mason (1997) shows that the diagnosis of schizophrenia using the ICD showed good predictive validity of the future involving the flat effect and disorganised behaviour
• Showing this is useful as it allows long term treatment and support to be planned for individual to manage their disorder over time

Question 11

Weakness of Validity

Answer 11

• One weakness is that Rosenhan demonstrated that nurses, clinicians and doctors were not able to differentiate between mentally disordered people and non mentally disordered just because they displace a symptom
• The follow up study also showed that professional would consider real patients as being fakes
• This demonstrates that in some setting the validity of these methods of diagnosis are low that healthy people may be labelled as mentally disordered