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Validity of IQ Test Scores
By Inderbir Kaur Sandhu, Ph.D
Q: 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 reasoning respectively
Nonverbal - 90, subtest t-scores of 50 & 37 for odd-item out and what's missing respectively
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.?
A: 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!.
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