Statistical infrequency

• how does it define abnormality?

  the way to define anything as abnormal or normal is according to the number of times we observe it

  any relatively usual behaviour or characteristic is normal and any behaviour that is different to this is unusual

  infrequent and rare behaviour is abnormal
• an example where this has been successful

  IQ - the majority of peoples scores will cluster around the average, the further above or below the average, the less people will have that score. the average IQ is 100, 2% have a score below 70 - these people are unusual and can receive a diagnosis of an intellectual disability disorder
• Limitation

  • unusual characteristics can be positive
  • IQs over 130 are just as unusual as scores below 70 - super intelligence is not viewed as a characteristic that needs treatment
  • just because very few people have a certain characteristic it doesn't mean that the behaviour is statistically abnormal
  • this concept would never be used to make a diagnosis
• Limitation

  • not everyone unusual benefits from a label
  • when someone is living a happy life, there is no benefit for them to be labelled as abnormal even if they are unusual
  • this label may have a negative effect on the way others view them and the way they view themselves
• Limitation

  • the cut of point is subjective
  • what is normal and what is not is open to interpretation