Discuss issues of reliability and validity associated with the classification and diagnosis of schizophrenia. (8+16)

An A grade essay I wrote for the 'issues of reliability and validity' topic within achizophrenia. Feel free to use as an example. ; )

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Amira Lakhouane
Discuss issues of reliability and validity associated with the classification and
diagnosis of schizophrenia. (8+16 marks)
Two of the most important classificatory systems for mental disorders, including
schizophrenia, are the `Diagnostic and Statistical Manual' (DSM-IV) and the
`International Classification of Diseases' (ICD-10).
For any diagnostic system to work effectively, it must possess reliability and validity.
Reliability means that there is good consistency over time (test-retest reliability)
and between the individuals who are using the system to rate patients (inter-rater
reliability). If two therapists often differ in their diagnosis of patients based on one of
the main diagnostic systems, this would suggest a low reliability for that system.
The reliability of the main classificatory systems can be questioned as the DSM (used
in the US) and the ICD (used in Europe) do not entirely agree on the number of
subtypes of schizophrenia, with the DMS claiming there to be 5 subtypes and the ICD
claiming 7. The issue here is that a sufferer could be diagnosed as one type of
schizophrenic according to the DSM (e.g. paranoid) and a different type according to
the ICD (e.g. disorganised), indicating low inter-rater reliability between the two
Moreover, in 1980 a new classification system called `DSM-III' was designed to provide
a much more reliable system for classifying mental disorders. Carson (1991) claimed
that this had fixed the problem for all inter-rater reliability once and for all. This
meant there could be much greater agreement over who did, or did not, have
schizophrenia. However, despite the claims of increased reliability, many years later
there is still little evidence that the DSM is regularly used with high reliability by
mental health clinicians. Recent studies have found inter-rater reliability to have
correlations as low as +11. Further problems have been illustrated in a study by
Rosenhan (1973) in which normal, healthy individuals tried to gain admission into
psychiatric hospitals. They all complained of hearing indistinct voices saying "empty,
"hollow" and "thud". All, but one were diagnosed as having schizophrenia and were
admitted. Throughout their stay, none of the staff recognised that they were actually
These findings seem to show that psychiatrists cannot diagnose schizophrenia with
any validity. However, there are various reasons for disagreeing with this conclusion.
First, because the individuals told of hearing voices to a psychiatric hospital, the
behaviour of the staff is quite predictable. Because they labelled these individuals as
having schizophrenia, it is doubted that we could argue convincingly that medical
science does not know how to diagnose that condition. Second, psychiatrists do not
expect totally healthy people to try to gain admittance to a psychiatric hospital.
Although errors of diagnosis were made under the very unusual conditions of
Rosenhan's study, this does not mean that psychiatrists cannot distinguish between

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Amira Lakhouane
the normal and the abnormal under more typical circumstances. Further, the ethical
issue of `deception' was committed as the staff were deceived, therefore limiting the
extent to which the study was ethically appropriate.
The second issue concerns validity; which means that a diagnostic system assesses
what it claims to be assessing. In the case of schizophrenia, it means that patients who
are diagnosed as suffering from schizophrenia actually have that mental disorder.…read more

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Amira Lakhouane
psychiatrist. Incidentally, the validity of the diagnosis of schizophrenia may be
limited due to high accounts of a Western cultural bias.…read more


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