Statistical Infrequency

• A mathematical way of identifying and explaining abnormal behaviour. Behaviour that is rare is assumed to be infrequent and therefore abnormal.
• Official statistics claim that 1 in 100 (1%) develop symptoms of schizophrenia which is considered rare, and therefore abnormal.
• When quantified, human behaviour falls in a ‘normal distribution’ with a central average and population that falls either side symmetrically. For example, intelligence test scores. Abnormality can be deciphered via how far away the score lies from the average.
• Approximately 5% of the population have an IQ that is more than 2 standard deviations away from the average of 100. Someone with an IQ of less than 100 is considered abnormal.
• Does not have to rely on subjective interpretations about what may or may not be considered abnormal. It reduces the likelihood of misinterpreting information which occurs in subjective definitions of abnormality such as deviation from social norms.
• Statistical infrequency can be used to assess normal/expected development in children. This means that this definition of abnormality has positive implications for making sure that children are developing as expected.
• Statistical infrequency uses data from established and standardised tests such as IQ assessments. So based on scientifically approved and widely used tests, and is therefore a scientifically credible way of establishing what is abnormal.
• Some rare behaviours are desirable. This means that there are behaviours that are statistically rare such as an IQ score as high as 130, or to be the fastest person alive, that are desirable yet infrequent.
• Does not take into account cultural differences. If a population is considered worldwide, then cultures with a smaller population that normalise certain behaviour that is not ‘normal’ in a larger culture could be neglected in the data, and the behaviour deemed problematic.
• One limitation of statistical infrequency is that it could lead to misdiagnosis, if infrequent behaviour is not rare. Approximately 10% of people worldwide suffer depression at some point in their lives, meaning it is technically not uncommon.