A video tutorial that explores the issue of when large differences in subtest scores within a composite tell us to ignore the composite score (Short answer: Not very often).
A video tutorial that explores the issue of when large differences in subtest scores within a composite tell us to ignore the composite score (Short answer: Not very often).
Assessing Psyche, Engaging Gauss, Seeking Sophia 
Thanks for this excellent tutorial ! Very easy to follow and very informative as well
Thanks! Glad you liked it.
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Is this approach (for lack of a better word) new? It seems like we were taught not to report FSIQ when there was significant scatter in grad school many years ago, and I still see reports where people say the FSIQ isn’t valid because of scatter. I think the report writer for the WISC-III did an auto text on scatter removing the FSIQ in the report it generated. So this really blew my mind. I shared it with my boss and she said it was a rabbit hole that made her think we shouldn’t report any composite scores at all. Can you clarify when/how this practice changed?
This idea has been around for a while. Several empirical demonstrations that scatter does not reduce the validity of the composite score have been published. Zack Roman and I wrote about the idea in detail and provided thorough demonstrations that the idea is correct in “Fine-Tuning Cross-Battery Assessment Procedures: After Follow-Up Testing, Use All Valid Scores, Cohesive or Not” https://doi.org/10.1177%2F0734282917722861
Since this video was more about within-composite differences, how i should view/interpret my own WAIS 4 profile, considering my index-scatter? I’m still (despite your informative video) in the dark and i cannot deny that it induces me with some level of anxiety. Sadly the psychologist didn’t really go into that “issue”.
My profile looks like this:
VCI 127
PRI 113
WMI 138
PSI 122
…resulting in an FSIQ of 130.
So there is a >23 pts gap between two indices and common practice dictates to see the FSIQ as non-unitary and “invalidated”. Would the FSIQ actually be invalidated or not in your view?
Many thanks!
I am sorry to learn that this issue induces anxiety in you. I hope that my answer puts you at ease. I am reluctant to comment specifically about your scores, so I will speak in more general terms.
To answer your question as directly as I can, a 23-point difference is a WAIS-IV profile is fairly common: More than a third of all people have differences of 23 points or greater in their WAIS-IV profile. The mere presence of a 23-point gap in a WAIS profile does not, by itself, signal that the person’s FSIQ is wrong, inaccurate, or not valid. Claims to the contrary, to my knowledge, are unfounded.
That said, if we already have reasons to be believe that a person misunderstood a test’s directions, failed give their best effort on a test, or was unable to give a test their full attention, a much lower score on that test might confirm that something was amiss and that any scores based on that test, including the FSIQ, may underestimate what the person’s abilities are when measured under optimal conditions.
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