Discrepancies in Test Scores
By Inderbir Kaur Sandhu, Ph.D
My daughter was tested at the end of 1st grade for a gifted
program. She scored in the 99 percentile on the Naglieri but
her scores on the Iowa Test of Basic Skills were in the
40's. All tests were administered one grade level above. Can
you help me understand why there is such a discrepancy
between the two scores? She just finished 2nd grade in a
normal classroom. She did well and her teacher again thought
she was very bright. She had independent spelling lists and
read in the high reading group but did not even score high
enough to be placed in a high ability cluster group within
Where do I go from here?
A: The Iowa Test of Basic
Skills (IBTS) is a nationally standardized test used across
the US. Test-takers are administered in the same way across
a specified reference population (e.g., age groups, grade
groups, etc.). Hence, the score interpretations are based on
a comparison of the test taker's performance to the
performance of other students in the nation, in short,
measuring students against their peers. As the test name
indicates, it measures basic skills such as vocabulary, word
analysis, reading comprehension and listening. On the other
hand, the The Naglieri Nonverbal Ability Test (NNAT)
measures ability without the requirement of reading,
writing, or speaking. The focus is on reasoning and
problem-solving skills which is considered ideal for those
with limited English proficiency.
The IBTS is a grade based achievement test while the NNAT is
an IQ test. This may clearly cause some differences in the
scores. It has been researched that gifted children are best
identified by reasoning tasks (such as verbal, spatial,
mathematical), and many score lower in processing skills,
such as visual-motor speed (as they may be reflective and
perfectionist) or short-term auditory memory (since their
memory for meaningful material may be much better than for
non-meaningful). These are usually the basics of IQ tests.
In contrast, achievement tests determine how advanced a
child is in academic subject areas such as reading, math,
writing, and spelling.
In your daughter's case, there appears to be some concerns
as she has high reading abilities. The full detailed break
down of the score is needed to interpret her scores and
determine weak areas that may have caused a drop in scores.
Perhaps, it would be a good idea to see someone from the
school for further advice on the scores. The most important
issue here is to identify her weak areas based on her grade
level and seek advice on what can be done to improve those
areas on concern. Best of luck.