Interpreting the RIAS scores
By Inderbir Kaur Sandhu, Ph.D
Q: I am trying to interpret my daughters
RIAS test scores. Her scores were as follows:
Verbal Index: Subset t-scores by age, Guess What 58: Verbal Reasoning
50, Cluster standard age score 107 with a 68 percentile by age.
Nonverbal Index: Odd item out Subset t-scores 67, What's missing 60,
cluster standard age score 126 with a 96 percentile by age.
Composite index 118(minimal estimate) 113-122, 88 percentile by age.
90% confidence interval 113-122.
Please help me understand these scores better. What is the cluster
standard age score and how does it come together to calculate IQ? What
is the IQ? Does the composite index fall within the 90% confidence
interval?
I was told for her to be accepted into the gifted program she needed to
score 130 or above. Looks like she missed it by a matter of 4 points if
its calculated based on cluster score of 126, but I am not sure if that
is how it was determined.
Statistics are part of my background so I am familiar but I am having
trouble interpretting these results. I appreciate you help.
A:
The Reynolds Intellectual Assessment Scale (RIAS is an individually
administered intelligence test, applicable to all ages from 3 to 94. It
comprises two subtests that assess verbal intelligence (VIX) and two
subtests that assess non-verbal intelligence (NIX). A verbal and
nonverbal supplementary memory test can also be administered (yields
Composite Memory Index score -CMX). It appears that the memory test was
not administered for your daughter, as it is supplementary.
The subtests that compose the VIX assess verbal reasoning ability along
with the ability to access and apply prior learning in solving language
related tasks. Although labelled the Verbal Intelligence Index, the VIX
is also a reasonable approximation of crystallized intelligence. The NIX
comprises subtests that assess nonverbal reasoning and spatial ability.
Although labeled the Nonverbal Intelligence Index, the NIX also provides
a reasonable approximation of fluid intelligence and spatial ability.
These two indexes of intellectual functioning are then combined to form
an overall Composite Intelligence Index (CIX). By combining the VIX and
the NIX into the CIX, a strong, reliable assessment of general
intelligence (g) is obtained. The CIX measures the two most important
aspects of general intelligence according to recent theories and
research findings: reasoning or fluid abilities and verbal or
crystallized abilities. Each of these indexes is expressed as an
age-corrected standard score that is scaled to a mean of 100 and a
standard deviation of 15. And as a rule of thumb, a score that is about
two standard deviation away from the mean is within the gifted range for
most test and for most placement in gifted programmes (in this case,
130).
Your daughter obtained a Composite Intelligence Index (CIX) of 118. This
level of performance falls within the range of scores designated as
above average and exceeds the performance of 88% of individuals at your
daughter’s age during testing. The chances are 90 out of 100 that her
true true CIX falls within the range of scores from 113-122 (confidence
interval).
Her Verbal Intelligence Index (VIX) of 107, which falls within the
average range of verbal intelligence skills and exceeds the performance
of 65% percent of individuals at that age. Her Nonverbal Intelligence
Index (NIX) of 126, which falls within the superior range of nonverbal
intelligence skills and exceeds the performance of 96% of individuals of
her age. This is not an intelligence quotient; it is the verbal
intelligence index.
There is no direct method to do the calculations – the raw scores are
converted to age-adjusted T-scores and the scorer would need to use a
manual for this. Each of these indexes is expressed as an age-corrected
standard score that is scaled to a mean of 100 and a standard deviation
of 15. These scores are normally distributed and can be converted to a
variety of other metrics if desired. Briefly, when correct responses are
added up across these verbal and nonverbal items, a good estimate of an
overall intelligence is obtained. In this case, this overall
intelligence score the CIX is 118, which is in the higher ability range
but not sufficient for a gifted programme (for your daughter’s school
the cut off is 130).
Hope this clarifies some doubts. Best of luck!
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