Historically, IQ was a score
obtained by dividing a person's
mental age score, obtained by
administering an intelligence
test, by the person's
chronological age, both
expressed in terms of years and
The resulting fraction
(quotient) was multiplied by 100
to obtain the IQ score.
For modern IQ tests, the raw
score is transformed to a normal
distribution with mean 100 and
standard deviation 15. This
results in approximately
two-thirds of the population
scoring between IQ 85 and IQ 115
and about 2.5 percent each above
130 and below 70.
IQ scores are used primarily in
the West for educational /
research placement, assessment
of intellectual ability, and
A concrete measure of
intelligence cannot be achieved
given the abstract nature of the
concept of "intelligence".
Scores from IQ tests are estimates of
There are a variety of individually administered IQ tests in use in the
English-thinking world. The most commonly used individual IQ test series
is the Wechsler Adult Intelligence Scale (WAIS) for adults and the Wechsler
Intelligence Scale for Children (WISC) for school-age test-takers.