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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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