Explain issues of reliability and validity associated with the classification and diagnosis of schizophrenia

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Laura Meaker
Explain issues of reliability and validity associated with the classification and
diagnosis of schizophrenia (3marks+16marks).
Schizophrenia is a disruption of cognition and emotion, which affects a person's
language, thought, perception, affect and even sense of self. Under DSMIVTR, the
diagnosis of schizophrenia requires at least onemonth duration of two or more `positive
symptoms'. Symptoms of schizophrenia are split into `positive symptoms' and `negative
symptoms'. Positive are those that appear to distort and add to normal functions.
Negative are those that decrease normal functions, which are often during periods of
low positive symptoms.
An example of positive symptoms includes delusions: bizarre beliefs that seem real to
the person with schizophrenia, but aren't real. Sometimes these beliefs are just
paranoia and sometimes they involve themselves. In contrast, an example of a negative
symptom is avolition. This is where there is a reduction of, or inability to, persist in
goaldirecting behaviours (e.g. they lay in bed all day).
When diagnosing a person with schizophrenia, it is important that it is both reliable and
valid. Reliability is the extent to which psychiatrics can agree on the same diagnosis
when reviewing patients individually. A `reliable' system called the DSMIII was created
in 1980 to classify the psychiatric disorder. Carson (1990) said that DSMIII had solved
this disagreement with reliability of psychiatric assessments because all psychiatrics
had the same system that should increase the agreement on who had schizophrenia
and who didn't. However, recent studies from Whaley (2001) found very low interrater
reliability correlations in the diagnosis of schizophrenia of just 0.11. In addition to this,
Rosenham (1973) found that the reliability of schizophrenia diagnosis' were not `up to
scratch'. Rosenham recruited 8 people (which he knew relatively well) and sent them to
a doctor to fake some symptoms of the disorder. They had reported to the doctors the
heard unfamiliar voices in their heads. These alleged voices were saying words such
as: `hollow', `empty' and `thud'. The doctor then diagnosed them with schizophrenia and
they were admitted to the psychiatric hospital. Throughout their stay, nobody recognised
that they were normal. In the follow up study, he warned hospitals of his intention to send
out more `pseudopatients'. This immediately resulted in approximately 21% detection
rate. Rosenham, however, didn't actually send any pseudopatients. This means the
hospitals could have then dismissed patients that may have truly suffered from this
disorder. Another study looked at interrater reliability between two psychiatrists when
considering the cases of 154 patients (Beck et al, 1961). The reliability rate was as low
as 54%: they only agreed on a diagnosis 54% of the 154 patients. Finally, Copeland et
al (1971) gave a description of a patient to 134 US and 194 British psychiatrists. 69%
of the US psychiatrists diagnosed schizophrenia, but only 2% of the British psychiatrists
gave the same diagnosis.
Laura Meaker

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Laura Meaker
Therefore, this clearly indicates the lack of reliability with the classification and
diagnosis of schizophrenia. This clearly shows the cultural variances in the diagnoses of
schizophrenia. If the DSMIII system was truly effective, the process of diagnosis and the
results would match entirely no matter what country it was in they do not match in this
Validity is the legitimacy of a study whether the findings can be applied to real life
(beyond the study).…read more


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