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Discrepancy between different IQ Scores - RAIS vs WISC

By Inderbir Kaur Sandhu, Ph.D

Q: I have a child who has twice been given the WISC with FS IQ scores in the middle to high 40's. As a young child she suffered from seizures but no brain damage was noted. The seizures were controlled with medication. She eventually "out grew" the seizures and has not been on medication for years. She is 14 years old. Caucasian. History of abandonment, sexual abuse, and neglect.

Currently, our local school system will not accept our psychologists evaluation and provide services that we feel she needs. Instead, they have evaluated her using the Reynolds where she obtained a FS IQ of 75. Her individual achievement scores are too high for her to qualify for having learning disabilities etc.

While I understand that these two different types of tests measure in a different way and will often produce slight differences in IQ, I am confused as to why there is such a huge discrepancy? Can you provide any feedback for me on this.

A: Briefly, the Reynolds Intellectual Assessment Scales (RAIS), considered as a newcomer in the world of intelligence testing, appears to be the shortest full-intelligence test compared to other intelligence assessment. It takes only about 35 minutes to administer. In contrast to most existing measures of intelligence, the RIAS eliminates dependence on motor coordination, visual-motor speed, and reading skills. The RAIS is divided into four sections: verbal intelligence index (VIX), a nonverbal intelligence index (NIX), a composite intelligence index (CIX) and a composite memory index (CMX). It can be administered to children as young as three up to 94 years. In this test, the subsets work together to create an overall score. Verbal intelligence is assessed with tasks involving. Non-verbal intelligence is assessed by visual and spatial ability tasks. In short, the verbal and nonverbal sections test the individual's knowledge of vocabulary as well as understanding of language for problem solving. Concurrently, the CIX and CMX test one's ability to create scenarios and also to remember facts, concepts and pieces of information that are subsequently used to solve problems.

The RIAS is a standardized test and have gained popularity over the years, probably due to the shorter time requirement compared to other tests. The reliability of this test is rather when compared to tests such as the WISC. However, research has also indicated that the RIAS scores tend to be a little higher than the scores from a WISC test.

On the other hand the WISC has been around for a long time (please see previous newsletter for information on the WISC). You did not indicate when she took the WISC. It may be possible that she may be better now (no more seizures) and with time perhaps learnt the system better. That can affect the IQ score. In any case, based on your description of her past, there can be many reasons for her to perform better on one test and not on another apart from the tests itself. However, you are right to be concerned of the discrepancy although I would feel that the WISC is a better indicator of any learning disability as compared to the RAIS. The RAIS was perhaps not able to capture her weak areas as well as the WISC, which may have caused a large difference in the scores among other factors.

As you are aware of, no two tests should be compared since they measure and capture different strengths. Especially when one takes only about 35 minutes to administer and another that takes up to 90 minutes. It breaks my heart that the school refuses to acknowledge her need for special education. I am not sure how you can do this, but she would really need some help – perhaps a team can be set up within the school to make a case to help this child. There are always exceptions to the rules of the system – one just needs to try really hard. I am hoping that she gets some help in making the case.

The assessment of children's abilities should always lead to a better understanding of the child. This is to enable appropriate recommendations and interventions to be made, regardless of whether that assessment is an individual or group assessment of ability or achievement, or on specific performance. At the end of the day, the motive is to help the child learn better in a system where the child is best matched. My very best wishes to you. Good luck!

Replied from reader: I really appreciate your in-depth assessment in regards to my question! It was very helpful.

Since my email, I have contacted our state advocate for education and held a meeting with the IEP team at her school. This made me very unpopular (ha) but too bad…my popularity is not the issue at hand. We declined their assessment and have asked for re-evaluation by an outside agency that is not connected to either party. The state is sending an advocate to attend our next meeting. I’m not going to stop until this child receives the services she qualifies for.

Again, thank you so much for taking the time to answer my question so thoroughly! 


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