NotesFAQContact Us
Search Tips
Peer reviewed Peer reviewed
Direct linkDirect link
ERIC Number: EJ776076
Record Type: Journal
Publication Date: 2007-Oct
Pages: 12
Abstractor: Author
Reference Count: 42
ISSN: ISSN-1934-9556
Defining Mental Retardation: A Matter of Life or Death
Lichten, William; Simon, Elliot W.
Intellectual and Developmental Disabilities, v45 n5 p335-346 Oct 2007
Because persons with mental retardation cannot be executed for murder, the diagnosis becomes a life and death matter. The American Association on Mental Retardation (now the American Association on Intellectual and Developmental Disabilities) and other associations agree that IQ alone is an insufficient criterion and adaptive functioning also needs to be considered. However, there is no satisfactory quantitative measure including both IQ and adaptive functioning. We propose a solution by defining a total quotient (TQ) scale, a composite of both IQ and standardized adaptive functioning scores. We estimate the margin of error in such scores (IQ, or adaptive functioning, or TQ) is 10 points, four times the usual one SD value given by intelligence test developers. The procedure here renders moot the distinction between convergent and divergent validity. This article provides an appendix for those readers who care to delve more deeply into the mathematics of TQ, IQ, and adaptive behavior scores. (Contains 4 tables.)
American Association on Intellectual and Developmental Disabilities. P.O. Box 7065, Lawrence, KS 66044-7065. Tel: 785-843-1235; Fax: 785-843-1274; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A