WISC-III (3rd Edition) has three composite scores, that should be provided to you:
  1. Verbal IQ (VIQ)
  2. Performance IQ (PIQ)
  3. Full Scale IQ (FSIQ)
Each of these IQs are composite scores.  Both the Verbal and Performance IQ scores are composites of five different subtests, each of which measures a different area of ability (this test is not an achievement test).  The Full Scale IQ is a composite of the Verbal and Performance scores, which makes it a composite of ten different subtests.

Check for a GAP between the Verbal IQ and the Performance IQ.  One indicator of a severe learning disability is when the gap is approaching two standard deviations (approximately 30 points or more); this would be looked at as a severe discrepancy.  Another indication is a severe discrepancy between the child's intelligence and educational test scores, or if there is a significant SCATTER between subtests scores.  The child may have perceptual or processing disorder.
(P. W.  D.  Wright and P. D. Wright (1983)).

WISC-III subtests:

Verbal Tests:
Performance Subtests (visual and vocal / visual motor task):
(As subtest described by The Psychological Assessment Resources, Inc.):

When subtest scores are in parentheses, this means that these scores are not computed as a part of the overall composite score. If you look at your child's scores, you will see that (Digit Span) and (Symbol Search) are in parentheses.  On the WISC-III, the Digit Span, Symbol Search and Mazes subtest scores are not included in the Verbal, Performance and Full Scale IQ scores. They are used to develop other composite scores.

When subtest scores vary a great deal, this is called subtest scatter. If significant scatter exists, this suggests that the child has areas of strength and weakness that need to be explored.

How can you determine if significant subtest scatter is present? Most subtests have a mean score of 10. Most children will score + or - 3 points away from the mean of 10, (i.e. most children will score between 7 and 13).

If the mean on a subtest is 10 (and most children score between 7 and 13), then scores between 9 and 11 will represent minimal subtest scatter.  Lets assume that Child A is given a test that is composed of 10 subtests. The child's scores on the 10 subtests are as follows: on 4 subtests, the child scores 10, on 3 subtests, the child scores 9, and on 3 subtests, the child scores 11.  In this case, the overall composite score is 10 and the scatter is very minimal.  This child scored in the average range in all 10 subtests.

In our next example, we will assume that Child B earns 4 subtest scores of 10, 3 scores of 4, and 3 scores of 16. The child did extremely well on 3 tests, very poorly on 3 tests, and average on 4 subtests. Again, the child's composite score would be 10. Subtest scatter is the difference between the highest and lowest scores.  In this case, subtest scatter would be 12 (16-4 = 12)  Is this an "average" child?  Because the child's scores demonstrate very significant subtest scatter, we need to know more about these weak and strong areas.

In educational situations, it is essential that parents understand the nature of the weak areas, what skills need to be learned to strengthen those areas, and how the strong areas can be used to help remediate the child's weak areas. The spread or variability between the subtest scores is called subtest scatter.

(P. W.  D.  Wright and P. D. Wright (1983))

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Sub scales:

Verbal Comprehension (VCI)
Perceptual Organization (POI)
Freedom from Distractibility (FDI)
Processing Speed (PSI)

Verbal Comprehension (VCI) score is calculated using:

Perceptual Organization (POI):
Freedom from Distractibility (FDI):
Processing Speed (PSI):

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The information on this was adapted from sited websites, Special Educator's Complete Guide to 109 Diagnostic Tests book,  parent discussions and emails. For more information  please visit these other websites:

Fairleigh Dickinson University, website created by Dumont/Willis

Harcourt Assessment, Inc, WISC III test


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One of our original webpages, created September 10, 2002, by Melody Orfei
Webpage last modified on February 28, 2007 - V15, by Melody Orfei