Gap between WPPSI-IV and SB V Test Scores
By Inderbir Kaur Sandhu, Ph.D
My 5.5 yr old daughter was evaluated individually for giftedness. She
was given the WPPSI-IV and had FSIQ of 148, GAI of 147. In the
subcategories, she was 99-99.9% (135-149) across the board. She maxed
out in the BD of VSI, PM of WMI, and Ca of PSI.
They also gave her the SB V test at the same time. On this, her SS on
the quantitative reasoning domain was 125.
Why the huge discrepancy between the WPPSI-IV score (148) and the SB V
score (125)? What does this mean?
In essence, comparing the same versions of individual IQ tests, such as
the Wechsler's to the SB, should be quite straightforward. But each test
has its own strengths. Psychologists suggest that matching the test to
the subject's strengths results in the most accurate IQ score. The
current version of the WISC (both IV and V) is a strong test for
verbally gifted children, with emphasis on knowledge gained from
reading. This version of the WISC, however, is also heavily timed.
Short-term memory and processing speed scales often lower the full scale
IQ score for gifted children.
Due to this, psychologists are usually familiar with the alternate
scoring, called the General Ability Index (GAI), in cases where the
difference between the verbal scale and short term memory or processing
speed scales exceed limits. The current version of the Stanford Binet,
the SB-5, is stronger for non-verbal intelligence, and less heavily
timed. Note that for the previous versions of both these tests, the
common wisdom was exactly the opposite: e.g., use the WISC-III for
non-verbal kids, and the SB-4 for verbal/ intelligence gifted kids.
Therefore, it can be concluded that any test can only measure a small
portion of a person's competence. Hence, in reality, all tests
underestimate children's abilities rather than overestimate them. It is
nearly impossible to fake abstract reasoning at an advanced level. When
a disabled child achieves two different IQ scores, the higher score is
believed to be the best estimate of the child's potential. Gifted
children should be estimated in the same manner. Speak to her testers to
get a detailed interpretation of the scores. Results also depended on
her level of readiness, fatigue, anxiety and rapport with the test
administrator. Since she was subjected to two tests on the same day, it
could well affect her performance especially with the second test.
Hope that helps clarify some doubts. For admission into advanced
programmes, use the WPSSI-IV scores. Best wishes to you!