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Discrepancy Between Verbal And Non-Verbal Scores On The K-BIT 2
By Inderbir Kaur Sandhu, Ph.D
Q: We firmly believe our daughter is ADHD but last year her school teacher and counselor rejected the idea because she does not struggle academically. She was 7 yrs old and in first grade when we requested she be tested to see if she was gifted because there are children that are gifted that do actually have ADHD. She was in a special advanced reading class and does very well with math.
A few days later the counselor did a K-BIT 2 test on her and mailed us the results. Her scores were: Verbal SS = 128, Matrices SS = 105, Composite IQ = 119. She was 7 yrs 2 mo on the test date. In the explanation of her scores it states that her score of 119 placed her at the 90th percentile rank meaning of 100 students her age she scored better than 90% of them. But then went on to explain "Verbal test score (128) and Nonverbal subtest (105) score were significantly different (<.01). A few more lines into the letter it states we need to monitor her progress in the classroom to be sure her visual problem solving continues to develop. "(Please understand, however, that her score of 105 is solidly in the average range. It is just significantly lower than her verbal ability score.)
What I would like to know is what the significant difference in scores really means. I am really just trying to find some insight into why her scores are so far apart and what that may mean for her in the future.
A: Firstly, just a brief explanation about the subtests for each on the KBIT-2. Both subtests that make up the verbal score measure verbal skills by assessing a person's knowledge of word meanings. Additionally, the verbal tasks measure the child's verbal concept formation, reasoning ability, and range of general information. The verbal score measures the Broad Ability known as Crystallized Ability, which reflects the amount of specific knowledge that a person has acquired within a culture and the person's ability to apply this knowledge effectively. The nonverbal score measures the person's ability to solve novel problems, those that are not specifically taught or trained. To solve the problems presented in the matrices subtest, the examinee needs to perceive various attributes in the pictures, generate hypotheses about how the pictures go together, and test out the hypotheses to arrive at a solution. Thus, the matrices subtest measures Fluid Reasoning and Visual Processing.
It clearly appears that your daughter has trouble with the measures of fluid reasoning and visual processing. The large discrepancy usually indicates a nonverbal learning difficulty.
The Composite IQ score (also known as Full Scale in some tests) is based on all or most of the subtests that is being tested. This is frequently the number most people refer to when discussing someone's IQ. Experts who develop intelligence tests use mathematical calculations to find the mean or average score. An IQ score from 90 to 110 is generally considered in the average range, corresponding to roughly 50 per cent of the population. The higher the IQ score, the lesser the percentage. For example, high scores of say 130 would only see about 2-3 per cent of the population. A higher score of 145 should occur in about 0.1 per cent of the time or once in a 1,000. Most gifted programs have a cut-off score around the 97th percentile. This would mean a standard score of 128.
Based on a mean of 100 and standard deviation of 15, your daughter scored in the average range (about 115-130 should be within the average range on a bell curve) for the K-BIT-2. The cut-off for a gifted education programme is usually 125-130 (your daughter scored 119) but can be on a case-by-case basis since there may be a diagnosis of a learning difficulty. You may need to see the tester to get the test interpreted in detail to be able to determine her weaker areas and get some help there.
The Kaufman Brief Intelligence Test (K-BIT) by definition is a “brief” intelligence test, also known as a test used for "screening" children. This means, the K-BIT2 test is just a few subtests of their KTEA (full version). Therefore, if those subtests are not the child's strongest areas, then the score could be quite different from the same child's score on the comparable “full” assessment. Having said that, test designers do select suitable subtests to include in a brief scale. This is not done randomly, rather using good research background.
One caution for you daughter especially if you believe that she may have ADHD; research has indicated that the Wechsler Abbreviated Scale of Intelligence (WASI) showed more stable measure of ADHD children's intelligence and that the KBIT-2 vocabulary scores were significantly lower than the WASI verbal score, and that there was a significant variability within the participants.
I would strongly suggest that you seek a second opinion if you wish for your daughter to be enrolled in a programme catered to her needs, as one brief test alone is insufficient to make diagnosis and decisions on her learning ability. Wishing you all the best in this journey!
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