Statistical infrequency

• Defining something as 'normal' and 'abnormal' according to how often we see it.
• Any relatively usual behaviour can be thought of as normal and anything different to this is considered abnormal.

Example: IQ and intellectual disability disorder

• Characteristics can be reliably measured - intelligence
• Majority of scores will cluster around the average
• The further we go above or below average, the fewer people will attain that score. (Normal distribution)
• Average IQ set at 100
• 68% have an IQ range from 85 to 115
• Only 2% have a score below 70
• Considered to be very unusual or abnormal and may recieve a diagnosis of IDD (previously known as mental retardation

• Diagnosis of IDD
• Therefore a place in thinking about normal and abnormal behaviours
• All assessments of patients with mental disorders require some kind of measurement of how severe symptoms are compared to statistical norms.
• Useful part of clinical assessment.

• IQ scores over 130 are just as unusual as below 70.
• Wouldn't think of super intelligence as an undersirable characteristic that requires treatment.
• Just because very few people display behaviours does make it statistically abnormal but doesn't mean treatment is required to return to normal.
• Never used alone to make a diagnosis.

• Where someone is living a happy, fulfilled life, there is no benefit from them being labelled.
• Someone with a very low IQ who is not distressed, can work normally, etc. would simply not need a diagnosis.
• May have a negative effect on the way others view them.