Difference in IQ Scores
By Inderbir Kaur Sandhu, Ph.D
I had my son privately tested when he was in first grade. He
scored a 137 on the WISC-IV. His school administered the
Test of Cognitive Skills when he was in third grade and he
received a score of 124. He said his teacher didn't tell him
what that test was for (entry into his school's gifted
program) and that it wasn't important; just do it. Could
this have affected his score? Which test more accurately
shows my child's true abilities?
A: No two different tests
should be compared in terms of the IQ scores, especially at
different ages as these tests are age-normed. The Test of
Cognitive Skills assesses academic aptitude that includes
verbal, nonverbal, and memory skills. It compares
achievement levels of students of the same age, grade, and
Interestingly, sometime back, a study on "The
Comparability of the Test of Cognitive Skills with the
Wechsler Intelligence Scale for Children-Revised and the
Stanford-Binet: Fourth Edition with Gifted Children"
indicated Full Scale IQ scores were over 10 points different
from their Test of Cognitive Skills (TCS) Cognitive Skills
Index. This clearly suggests that there is a limited
comparability between TCS and WISC-R and SBIV.
Sometimes, children may not take tests seriously and this
may affect the scores to a certain extent, but not to a
great extent. Taking a test in a relaxed manner and when
stressed may even out the scores depending on the
individual. The best thing to do is to approach his teacher
to be more familiar with the interpretation of the scores
which will enable you to guide him further.