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IQ Testing

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My son is 19 years old and intellectually disabled. We applied for SSI for him and they are requiring him to take another IQ test. He took one at age 10 (Full IQ = 56, subsets ranging 55-72) and another at age 13 (Full IQ = 50, subsets ranging 55-62). Both were WISC-III. Now he will be taking the WAIS-IV and my question is, how closely will the WISC numbers correspond to the WAIS? I know that IQ is a fluid, not an absolute number, but I want to know some generalizations so if the examiner comes up with an out-of-left field number, I can dispute it. Thanks.

IQ Testing

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The correlation between the two tests is very good in the studies — with a score of 1.00 being perfect the correlations run about .90. This means that the chances are very good that the WAIS score will be reasonably close to the other scores obtained.

Testing on the WAIS is typical when a disability claim is filed. If the number is off by more than 10-15 points from the last test and you want to dispute it you may want to consult with a lawyer familiar with SSDI to learn about your son’s rights.

Wishing you patience and peace,
Dr. Dan
Proof Positive Blog @ PsychCentral

IQ Testing

Daniel J. Tomasulo, PhD, TEP, MFA, MAPP

Dan Tomasulo Ph.D., TEP, MFA, MAPP teaches Positive Psychology in the graduate program of Counseling and Clinical Psychology at Columbia University, Teachers College and works with Martin Seligman, the Father of Positive Psychology in the Masters of Applied Positive Psychology (MAPP) program at the University of Pennsylvania. He is Director of the New York Certification in Positive Psychology for the Open Center in New York City and on faculty at New Jersey City University. Sharecare has honored him as one of the top 10 online influencers on the topic of depression. For more information go to: He also writes for Psych Central's Ask the Therapist column and the Proof Positive blog.

APA Reference
Tomasulo, D. (2018). IQ Testing. Psych Central. Retrieved on May 23, 2019, from
Scientifically Reviewed
Last updated: 8 May 2018
Last reviewed: By a member of our scientific advisory board on 8 May 2018
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