Definitions of abnormality - statistical infrequency

• Statistical infrequency 


  • suggests that abnormality is defined as any behaviour which is numerically uncommon and therefore not seen very often in society.
• What is the average IQ ?


  • average IQ is 100 and most people have an IQ of between 85 and 115 which is also considered normal.
• What numbers fall outside of normal?


  • if it was 2 standard deviations away from the mean the IQ is between 70-130, which fall outside of normal.
  • for example, an IQ of 70 is very low and somebody wiYh this IQ would be told they have intellectual disability order
  • However, roughly 2% are below 70 and 2% are above 130
• AO3: cultural relativism

  • A limitation of statistical infrequency definition is that it is relative to the culture in which the behaviour is being assessed
  • Classification systems like the DSM are based on Western cultures
  • However, cultures differ in terms of statistical infrequency and social norms
  • Therefore, there are no universal standards or rules for labelling behaviours as abnormal
• AO3: some abnormal behaviour is desirable

  • A limitation of the statistical infrequency definition of abnormality is that some statistically abnormal behaviour can also be positive
  • Just because a person’s behaviour is statistically abnormal it does not mean the person required treatment
  • For example, IQ scores over 130 are just as unusual as those below 70, but not regarded as undesirable and requiring treatment
  • This is a serious limitation of the concept of statistical infrequency and means it should never be used alone to make a diagnosis
• AO3: cut-off point is subjectively determined

  • A limitation of the statistical infrequency definition is that cut-off points are subjectively determined
  • For example, people disagree on what constitutes an abnormal lack of sleep
  • However, since this is a symptom of depression, it is important to know where the cut-off point lies for a diagnosis to be made
  • This means that disagreements about cut-off points make it difficult to define abnormality in terms of statistical infrequency