Validity of IQ Test Scores
By Inderbir Kaur Sandhu, Ph.D
We just received gifted testing results from the school district and I
have concerns about the results that I would like some advice on prior
to my meeting with school staff next week.
My concern is regarding the nonverbal results from the Reynolds
Intellectual Assessment Scales. According to the results, my 6-year old
son scored at the 25th percentile with a score of 90 (t-scores of 50 and
37 for odd-item out and what's missing respectively).
While I realize this is a lengthier testing instrument and differs
somewhat from the KBIT II which was administered last spring, the
results are wildly differing! On that scale his nonverbal score was 133
(which I understand meets the gifted threshold for that subset).
Here are the results I have received:
From the KBIT II administered 4/2013:
Verbal - 113
Nonverbal - 133
Composite - 127
From the Reynolds Intellectual Assessment Scales:
Verbal - 118, subtest t-scores of 56 & 64 for guess what & verbal
Nonverbal - 90, subtest t-scores of 50 & 37 for odd-item out and what's
Composite - 104
Am I justified in questioning the validity of these results? We are
talking about a child who knew all the sounds to his alphabet at 18
months and was reading (not just memorizing) at age 2 1/2.
Do you have any suggestions for the meeting with staff in terms of
questions to ask, etc.?
My apologies for the delay as the queries are attended to in queue. I
hope the matter has been satisfactorily resolved by now. The Reynolds
Intellectual Assessment Scale (RIAS) is an individual test designed to
measure general intelligence, while eliminating dependence on motor
coordination, visual-motor speed, and reading skills.
The Verbal Intelligence Index (VIX) assesses verbal intelligence by
measuring verbal problem solving and verbal reasoning where acquired
knowledge and skills are important. In addition, it assesses
verbal-analytical reasoning with fewer vocabulary and general knowledge
demands than the other subtest. The RIAS Nonverbal Intelligence Index
(NIX) measures nonverbal reasoning skills that require the use of
spatial ability and visual imagery. In addition, it measures nonverbal
reasoning, which requires conceptualization of a picture, analysis of
its gestalt, and deduction of what essential element is missing. The
RIAS Composite Intelligence Index (CIX) is a summary estimate of global
intelligence. Both the VIX and the NIX have significant correlations
with academic performance, although as expected, the VIX correlates more
highly with academic skills.
On the other hand, The Kaufman Brief Intelligence Test - Second Edition
(KBIT-2) is a brief, individually administered measure of verbal and
nonverbal cognitive ability. The KBIT-2 yields three scores: Verbal,
Nonverbal, and the IQ Composite. The Verbal score comprises two subtests
(Verbal Knowledge and Riddles) and measures verbal, school-related
skills by assessing a person’s word knowledge, range of general
information, verbal concept formation, and reasoning ability. The
Nonverbal score (the Matrices subtest) measures the ability to perceive
relationships and complete visual analogies. All Matrices items involve
pictures or abstract designs rather than words.
From the results, they may appear puzzling that on one test the scores
are rather high while on another it is quite the opposite. The composite
score for K-BIT 2 indicated a score in the above average range while on
the RIAS, it merely shows average performance. In fact, the verbal
ability is higher on the RIAS; but on K-BIT 2 the non-verbal ability is
in the superior range. Having noted that, these are two quite different
tests and cannot be compared as such. The K-Bit 2 is at best a screener
for intellectual abilities and best if not used for purposes of
diagnosis or placement. It is important that it is used as a screening
tool, and not the be-all end-all measure of intelligence. For that
purpose, a more comprehensive assessment would most likely be necessary-
such as the RIAS.
You would need to discuss the scores with the school and get them to
help you understand the concern. The K-BIT 2 score is from last year and
you need to find out what happened in between for his to have much lower
score on the RIAS non-verbal. His verbal ability appears quite
consistent. Perhaps the tester may be able to shed some light here. In
any case, you are right to question the scores especially since the
difference quite remarkable. They may be able to analyse the difference
better by retesting should it be necessary. All the best!.