# definitions of abnormality - statistical deviation

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Statistical Deviation
Behaviors that are statistically rare should be seen as abnormal. A behaviour is determined as being 'normal' or 'abnormal' depending on how frequently it occurs in the population.
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how would you establish a statistical deviation?
statisticians measure characteristics and behaviours across a population and draw a graph to demonstrate the normal distribution - the proportion of people who share those characteristics or behaviours.
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normal distribution
a symmetrical bell curve; most scores are in the middle area of the curve and the mode, median and mean all occupy the mid-point. the extreme scores never touch the x axis because theoretically more extreme scares are possible.
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skewed distribution
a spread of data that does not produce a symmetrical bell curve - it leans to one side to another.
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positive skew
a curve leans to the left, resulting in a long tail to the right. E.g. in a difficult test most people achieve low marks.
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negative skew
the curve leans to the right. meaning most people achieved higher scores E.g. in an easy test
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positive evaluation point 1 - statistical deviation
is a useful tool for clinicians to use when assessing an individual, it uses statistical data to identify those who exhibit unusual characteristics. EXAMPLE: they can establish those who have a low IQ and need help can be diagnosed then helped.
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positive evaluation point 2 - statistical deviation
the use of statistical data means that it has been collected objectively - which is regarded as more scientific and preferable to a diagnosis based on a subjective assessment of information provided by a patient.
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negative evaluation point 1 - statistical deviation
it is too simplistic in its assumption that uncommon means abnormal; unusual characteristics can be positive.
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negative evaluation point 2 - statistical deviation
statistical deviation only considers the quantitative measure of how unusual a behaviour is.
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negative evaluation point 3 - statistical deviation
not all abnormal behaviours are statistically infrequent. about 10% of the population will be diagnosed as depressed at some point in their lives, which makes it so common that it would not be identified as abnormal by a test of statistical deviation
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negative evaluation point 4 - statistical deviation
this definition does not consider that there may be cultural differences in behaviour across a population.
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## Other cards in this set

### Card 2

#### Front

statisticians measure characteristics and behaviours across a population and draw a graph to demonstrate the normal distribution - the proportion of people who share those characteristics or behaviours.

#### Back

how would you establish a statistical deviation?

### Card 3

#### Front

a symmetrical bell curve; most scores are in the middle area of the curve and the mode, median and mean all occupy the mid-point. the extreme scores never touch the x axis because theoretically more extreme scares are possible.

### Card 4

#### Front

a spread of data that does not produce a symmetrical bell curve - it leans to one side to another.

### Card 5

#### Front

a curve leans to the left, resulting in a long tail to the right. E.g. in a difficult test most people achieve low marks.