The current scoring method for all IQ tests is the "deviation IQ".
In this method, an IQ score of 100 means that the test-taker's performance
on the test is at the median level of performance in the sample of test-takers
of about the same age used to norm the test.
An IQ score of 115 means performance one standard deviation above the median,
a score of 85 performance, one standard deviation below the median, and so on.[5]
Lewis Terman and other early developers of IQ tests noticed that
most child IQ scores come out to approximately the same number by either procedure.
Deviation IQs are now used for standard scoring of all IQ tests in large part because
they allow a consistent definition of IQ for both children and adults.
By the current "deviation IQ" definition of IQ test standard scores,
about two-thirds of all test-takers obtain scores from 85 to 115,
and about 5 percent of the population scores above 125.[6]
All IQ tests show variation in scores even when the same person takes the same test
over and over again.[7][8]
IQ scores also differ for a test-taker taking tests from more than one publisher
at the same age.[9]
The various test publishers do not use uniform names or definitions
for IQ score classifications.
|