Validity of IQ Test Scores
By Inderbir Kaur Sandhu, Ph.D
My daughter received the WISC-IV at age 6 and obtained a full-scale
score of 135. She also took the WIAT-II and scored within the 99.5
percentile in most areas. She is now 9 and the school wants to retest
her. They say that she was young at the time of testing and her scores
may not be accurate. She has skipped a grade and maintains an A average
and is socially doing well. Is retesting her really necessary? How long
are the scores valid for the tests she already took?
Intelligence tests, the standardised ones that are properly
administered, accurately measured and interpreted, are believed to be
the single, most accurate predictor of general intelligence and it does
provides a snapshot of intellectual functioning at a point in time.
Having said that, these scores may not be stable until around seven
years of age, which is due to the rapid rate of neuropsychological
development in early childhood.
What this means is that although your IQ at age ten is strongly
predictive of your IQ. This means that one's IQ score at age 10 is
probably more predictive of a stable IQ at say, 60 years of age, but an
IQ score at age four or five, would probably be a good predictor of
general intellectual functioning at that age, rather than a similar
score at age 60. These tests are normed on standardisation groups that
are six months to one year apart, and age is considered in the scoring.
Intelligence tests have a validity of two years; therefore the school
may feel the need to get your daughter retested. You may need to find
out the reason apart from the age factor when she was first tested.
Especially since she has been accelerated and doing well in her current
programme, with no other issues I believe, I really don't see a good
reason for subjecting the child to testing. Of course, unless this is
the uniform policy in the school and applies to all children, you may
want to speak to some in the school for a better explanation.
Hope that helps clear some doubts. Good luck.