Schziophrenia- Reliability & Validity Essay

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Jessica Leigh
Grade B
Discuss the issues surrounding the reliability and validity of the
diagnostic systems for Schizophrenia.
The term reliability refers to the consistency of diagnosis when referred to in
psychological terms. The reliability of a diagnosis can be checked in two ways.
The first process is called `test-retest'. This is when the same doctor
re-diagnoses a patient several months later. If the diagnosis is the same, then the
method of diagnosis is seen to be reliable. However, many doctors are likely to be
bias and favour their first diagnosis, to stop them being wrong in the first place.
The second process that can be used to check reliability is called `inter-rater'.
This is when several doctors assess and diagnose the same patient. If the
diagnoses are the same, they are therefore seen to be reliable. However
problems with reliability often occur. They are usually caused by the classification
tools used in the diagnosis period. Each culture has a different classification tool.
Although they are all similar, certain aspects are different. Here is the UK; we use
the ICD (International Classification system for disease. The duration of the
classification system is only one month. The system fails to take into account
individual differences such as class and culture. The ICD is therefore not
multi-axial. The system has seven subtypes for diagnosing Schizophrenia; these
will be spoken about later. In the USA they use the DSM (Diagnostic statistical
manual). The diagnosis and observation period lasts 6 months. Unlike the ICD, the
tool takes into account other factors such as class culture and individual
difference. This is measured using the GAF scale which then gives an average
score on the ability of a person to function. The DSM is therefore multi-axial.
The DSM has five main sub types which are also present in the ICD. These are;
paranoid, undifferentiated, residual, catatonic and disorganised. The ICD has
two extra sub types which are called; simple schizophrenia and post
schizophrenia. The changes and differences in both of these classification tools
affect both the reliability and validity. The small duration period in the ICD means
there is less time for a good diagnosis results being given. This lowers the chances
of the diagnosis results being consistent which will affect the reliability. The fact
the ICD is not multi axial also lowers the reliability as if one patient was to have a
inter rate reliability test in the UK then the individual differences and their
background is likely to be different as there is less subtypes in the DSM than the
ICD. The fact there is less sub type's lowers rooms for error but the patient may
also be given the wrong diagnosis and they don't perfectly fit into one category.

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Jessica Leigh
Grade B
The validity is also a problem that occurs when diagnosis mental health patients
with disorders such as schizophrenia. The term validity refers to the accuracy of
the diagnosis. It can be checked in several ways. Firstly for a diagnosis to be valid
it must be reliable. You could use predictive validity which is similar to trial and
error. You come up with a diagnosis' and give the patient drugs.…read more

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Jessica Leigh
Grade B
change depending on the country they are in. This is because of cultural
differences and sub type differences. Research has found that African Americans
are more likely to be diagnosed than white Americans because of their cultural
differences. The DSM helps to stop this as its multi axial and takes culture into
consideration. Most patients are then thrown into the undifferentiated
schizophrenia category.…read more


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