Statistical Infrequency

• This is a way of literally drawing a line between normal and abnormal. Simply if behaviour is numerically uncommon or rare, then it is abnormal. The more uncommon, the more unusual.

  Psychologists use histograms to show the pattern of distribution within a population.
• Evaluation of Statistical Infrequency as a definition of Abnormality


  • This is a very objective way of defining abnormality in comparison to other definitions.
  • There is no personal judgement involved and has little room for personal opinions to affect our perception of what is abnormal.
  • This is important because it means this definition may be a better way of describing abnormality as personal opinions do not influence whether a person is abnormal or not
• Evaluation of Statistical Infrequency as a definition of Abnormality



  • Someone has to decide where the line is between normal and abnormal
  • The consequences of where this line is drawn can make huge difference to lives. For example, a child with an IQ of 31 may be considered 'normal' and wont get access to Special Needs support, whereas a child with an IQ of 30 may be classified 'abnormal'
  • This is a problem because both children may need extra support. Because of this, the Statistical Infrequency definition is defective.
• Evaluation of Statistical Infrequency as a definition of Abnormality



  • Many mental health disorders are not statistically rare or uncommon
  • For example, statistics say that in a lifetime 1 in 14 people will self-harm. Common psychological disorders are not rare, but they are still important to treat
  • This is important because it means that this method of assigning people abnormal will not work for common mental health issues. Because of this the Statistical Infrequency definition is defective
• Evaluation of Statistical Infrequency as a definition of Abnormality



  • Some behaviours are statistically rare and highly desirable
  • For example, having an exceptionally high IQ, or being extraordinarily old may be abnormal according to the definition, but this doesn't mean they are bad
  • This is important because it means that this definition will not always show that someone is abnormal, just that they are unique