The RIAS Vs WISC
By Inderbir Kaur Sandhu, Ph.D
My daughter took RIAS, school psychologist administered when she was 5
yrs 8 months. She scored verbal 142 nonverbal 150 and composite 154.
I wanted to sign her her for the Davidson young scholars. You must have
full scale IQ of 145. I thought she would be close since her composite
score was 154 in RIAS but They don't take the RIAS. She was given WISC-V
last week she is know 6 years 11 months. Her scores were verbal 130,
visual 135,fluid reasoning 126, working memory 122, processing slows
123, full scale 133.
Why are the wisc scores so much lower? I don't see point in trying
again. If she want to join a special group that would need it later she
can make the decision to restart. But am wondering if the RIAS was
scored too high or if the wisc-v is underscoring her? I didn't think
there would have been a 21 point difference.
As a matter of fact, no two tests should be compared since they measure
and capture different strengths. Especially when one takes only about 35
minutes to administer (RIAS) and the other (WISC) that could take up to
90 minutes. However, I do find that the discrepancy is rather large
which could be due to any reason as there is over a year gap.
Both instruments measure different constructs. It has been hypothesized
that the RIAS would score higher given the additional psychomotor
processing and working memory factors on the WISC. Therefore, we are
actually measuring similar yet different aspects of cognition. Research
has indicated that RIAS tends to score approximately 10 points higher
than the WISC-IV on global cognitive ability measure (this would be
similar to the WISC-V). Working Memory and Processing Speed tends to
depress the WISC FSIQ; which is quite obvious in your daughter’s case.
However, the discrepancies between scores are not large enough to
calculate a GAI index (which does not take in to account PS and WM). It
has been argued that the difference in both RIAS and WISC is really in
the nonverbal sections of the tests.
In any case, she is obviously above average and could do with a gifted
programme to have match between her abilities and her learning. This
would be something you could find out further. Even though many studies
comparing RIAS with WISC indicates that RIAS scores higher on all
measures and through all age groups, both instruments correlate fairly
well with a high degree of confidence when comparing global IQ scores.
This indicates fairly good reliability and validity of RIAS.
As for whether underscoring or over scoring happened, it depends on a
lot of factors; the administrator’s training, child’s state of mind
(anxiety, fatigue, stress, etc.), physical health at the point of
testing, and so on. Therefore, it is always best to test with a trained
psychologist and taking into account the child’s readiness and state of
mind. Hope that helps. Best of luck.