The use of IQ and descriptions of people with intellectual disabilities in the scientific literature

A necessary though not sufficient part of most internationally recognised definitions of Intellectual Disability (ID) is having a measured intellectual quotient (IQ) less than a critical figure, usually 70, for example the American Association on Intellectual and Developmental Disabilities (AAIDD, 2010), the World Health Organisation (WHO, 1996), and the American Psychiatric Association (APS, 2000). Measured IQ is therefore one of the major descriptors of people with ID in the scientific literature as well as being an important independent or dependent variable. However, recent work on the accuracy to which low IQ can be measured has suggested that degree of error is much greater than had previously been thought.