Statistic infrequency

• Unusual characteristics can be positive

  For example, a very high IQ is unusual but is not undesirable and does not need treatment.

  This means that statistical infrequency is never used alone to make a diagnosis.
• Subjectively determined

  It is hard to determine common and statistically infrequent behaviour. This is because it is not clear how numerically rare the behaviour has to be considered abnormal.