Just got results back from the WIAT III for my 10 year old. Actual WIAT scores are all significantly different than predicted WIAT (based on FSIQ of 152). Actual Total Achievement score on WIAT was 158 but the predicted score was 139 based on the WISC scores (difference of -19).
I can find lots of information (suggesting learning disabilities) when there is a significant difference between wiat and wisc the other way around (performance lower than iq) but nothing that would help us figure out why such a discrepancy the other way? Is this normal in gifted kids?

Additionally, the test was administered at grade 10 level (even though he is in grade 5) and he completed most of the questions accurately in about a third of the allotted time

So actually, there is no such thing as taking the test at the grade 10 level as a grade 5 student, unless it was scored out-of-level using grade 10 norms (which it would appear it was not; if it was, then this would become a different discussion altogether). The difference between the grades is encompassed in the design of the test basals and ceilings, with the exception of the Reading Comprehension and Oral Reading Fluency subtests, which have grade-based item sets. But administering out-of-level in the way you describe, while possibly clinically informative, would not generate standard scores for those two subtests. I suppose they could have started him at the grade 10 start points instead of grade 5, but all of those are actually called grade 9-10 start points, so it would be unexpected to call them grade 10 (and the same issue with item sets still exists).

Not sure what they considered a third of the allotted time. FWIW, it usually takes about 1.5 - 2 hours to complete. About 20 minutes of it is quite difficult to complete more quickly while also performing at a high level (i.e., usually those sections go quickly only when a student gets very few items correct; some of them are timed with minima, and others are limited by how quickly the examiner can physically proceed through the stimulus items).

To your more important question: no, there is probably no significance to achievement scores well above the scores predicted by the WISC-V FSIQ. Predicted scores take into account regression to the mean, in the form of correlation coefficients as obtained through the linking studies. As a rough example of this, say the correlation coefficients obtained for Total Achievement as predicted by FSIQ is .75 (which is around the vicinity of true). The FSIQ is +52 SS above the mean. 52x0.75 = 39. The mean (100) + 39 = 139. Hence the predicted score.

Then one should take into account the difference in scores that would be considered statistically significant and rare. A typical critical value for significance at the .05 or .01 level would be about 7 or 9, respectively, with a base rate considered to be rare (<10% or <5%) falling somewhere around 12-15 -ish standard score difference. That is, until the difference in scores (in this example) is more than about 15 points off of the predicted score, it isn't considered remarkable in either direction. That would be 154 in this case, not that far off his actual score. (And I'm not using the real tables in this case.) In any case, the point of regression to the mean is that one or the other (or both) score might have error in it that veers slightly high or slightly low, and the predicted scores try to take that into account. If both scores were more accurate than standard error would have predicted, you would get more correspondence between them than regression to the mean might have predicted.

Probably more psychometrics than you wanted to read...but the bottom line is that this isn't wildly out of line with his assessed cognitive ability. And also, he is likely up in the ceiling of the test.

ETA: should have looked back at your previous post first...you may recall that I suggested that his assessed GAI and FSIQ are likely low estiamtes of his true ability. So if his extended GAI is notably higher than the standard norms suggest, it would be even less surprising that his achievement scores are in this range. I would again suggest that (if this matters to you for access to resources or other items of value to your family) there may be utility in obtaining the extended scores from the original evaluator (or, if you do not need the numbers formally, but have the raw scores and want extended scores, pm me).

Wow AEH, you are so unbelievably kind to provide such detailed responses....thank you!

"In order to help to
establish whether ____ was adequately stimulated in the classroom, a higher
level of the WIAT III was administered. The WIAT III was administered at a Grade .
10 level, for Reading Comprehension and Reading Fluency"

"He finished the reading fluency test in a little over a third of the
allotted time without making a single error."
This is how the examiner wrote it up in the report.
So yeah, just speaking about the reading section apparently.

These are the scores from the Ability-Achievement Discrepancy Analysis Predicted Method section of the report. The first number is the Predicted WIAT-III Score, the second number was his actual WIAT-III Score, then the spread/Difference and lastly she put a Y or N to note if it was a "Significant
Difference"

WIAT-III Subtest
Listening Comprehension 136 135 1 N
Reading Comprehension 134 160 -26 Y*
Math Problem Solving 134 160 -26 Y*
Sentence Composition 129 155 -26 Y*
Word Reading 126 145 -19 Y*
Pseudoword Decoding 121 136 -15 Y*
Numerical Operations 131 160 -29 Y*
Oral Expression 134 152 -18 Y*
Oral Reading Fluency 123 152 -29 Y*
Spelling 129 154 -25 Y*

WIAT-III Composite
Oral Language 139 148 -9 N
Total Reading 131 156 -25 Y*
Basic Reading 123 150 -27 Y*
Reading Comprehension and Fluency 136 160 -24 Y*
Written Expression 129 154 -25 Y*
Mathematics 136 160 -24 Y*
Math Fluency 136 141 -5 N
Total Achievement 139 158 -19 Y*

Good to know that these discrepancies are not something we need to really pay attention to. I just saw these flagged as "significant" and was wondering if it indicted anything we should be worrying about/focusing on. Your explanation was fantastic - thanks for that.

The biggest reason we got these tests done was to figure out where/if he might need subject acceleration at school. At the recent parent-teacher interviews the teacher suggested he may be cheating or looking at the answers at the back of the book because he was writing down the answers to math problems without showing his work. He said it was because he could figure them out easily in his head and I felt I needed to bring some "proof" to the school to advocate for more of a challenge. He is in his first year at a gifted charter school (grade 5), so I was somewhat surprised to hear this comment and thought maybe he was still not being challenged enough - even in an advanced school - thus the testing to see where his strengths may be. The school has not really provided "grades" as such so far this year, as most of his work has been integrated project work and when we asked how he was doing in individual subjects, the teacher said it was hard to tell and used that example of writing down the math answers so quickly.

So, while it would be interesting to ask for the raw scores, and see how things would look with the extended data, I don't know that we need them for anything formal at this time. I am really hoping to use these results (from WIAT) to meet with the school and come up with a plan - even within this designated gifted school - to make sure he is not still bored.

The school was also saying they had some concerns about autism or ADHD, so we had all of that tested for at this time as well - using: the Connors behavior rating scale, the Connors Executive Functioning Inventory, Autism Spectrum Rating Scale, and that the CPT 3 and CATA, and the Cognitive Assessment System 2 ,CAS2.

DSM-5 criteria for Autism Spectrum Disorder yielded a T-score
of 48 (90% CI = 45-51), which is ranked at the 42nd percentile and falls in the Average Score range.

Additionally, the clinical interview and behavioral observations did not support the diagnosis of ADHD. He was able to focus during both the continuous performance test and
achieved an excellent level of attention on the CAS2.

I will be also bringing these findings to the school and hopefully this will also help! My suspicion is that the energetic behaviors, etc that the school was saying were autism or ADHD were due to (still) boredom with the level of curriculum, and this was supported by the psychologist who administered these tests.

Anyway - thanks for listening!! This place is such a great resource.

Happy to help. And good to know that you've been able to definitively clear up the school nudges regarding ASD and ADHD.

I think you are exactly correct: his instructional needs likely far surpass what even this GT school offers. I'm deeply underimpressed by the GT teacher never having encountered a student gifted in math who doesn't show work because "there aren't any steps" (as one of my math-gifted siblings once said, in response to a similar complaint). Not sure what kind of GT students they've been teaching previously.

Although keep in mind that, if their average GT student is in the 130s, your DC is statistically at least as far above them in giftedness as they are above a neurotypical learner (likely more, since his scores are clearly a lower limit on his reasoning ability). So despite being GT-trained educators, the teachers may be as out of their depth with him as a classroom teacher at a comprehensive would be with one of the typical students at the GT school.