Glossary

A study which follows the same participants over a substantial period of time – usually several years.

The term used by the World Health Organisation and other international agencies to refer to countries where income falls below a certain level. A more meaningful category than ‘developing countries’ or ‘under-developed countries’, terms which are nowadays regarded as inappropriate.

A term used by some specialists to describe cases of autism where the individuals' full-scale IQ score is below 70, i.e. in the disabled range. This is not a formal diagnostic category, but rather a term sometimes used informally in diagnosis as well as in everyday situations and research. See also high-functioning.