Gifted Issues Discussion homepage Forums Identification, Testing & Assessment WIAT higher than WISC?

Does anyone know if it means anything that my daughter's WIAT test results are much higher than predicted by the WISC?

Her FSIQ - 134, with a lower processing speed
WIAT Math = 160 (predicted 122)
Reading = 137 (predicted 120)
Written Language = 144 (predicted 118)
Oral Language = 151 (predicted 121)

I've posted before about the math, but now that I have all of the results, I am curious as to why someone might 'overperform' across the board on the achievement tests. It seems to me like the opposite would be more likely. No 2e issues or anything and she's definitely a hard worker -- maybe that's all it is? Anyone experience something similar?

Exposure to higher level material?

With the right effort and exposure it is nearly always possible to improve how well you do. There are limits to this but it doesn't seem unreasonable - especially if processing speed is depressing he FSIQ but not her WIAT (don't know the test).

IQ is the fixed-ish bit that achievement can leverage off of. Figure then that hard work and opportunity interact with IQ to get achievement results. Opportunity wouldn't just be the socie-economic stuff either, it would include how well the school meets them at their level of challenge. It seems like 3/4s of the folks here have kids who are being underchallenged at school so that would likely depress their relative achievement.

Where do these predictions come from (WISC scores predicting WIAT) scores?

At some point somebody co-normed and correlated on the same national sample both of these tests...so there is some table or some app that you put in the WISC score and it gives you the predicted wiat.

To me this just indicates that the gai might be a better indicator...I bet if you stuck the gai in the magic predictor app the adjusted scores would have had better predictive value

tortuga, my children have had the WISC but not the WIAT so I am not familiar with WISC/WIAT combo scoring or how the prediction is made. My kids have had the combination of WJ-III Cognitive + Abilities tests, which also gives a predicted measure, and with that battery the predictions are made based on different combinations of individual cognitive subtests compared against broad reading/math/writing etc achievement subtests. I suspect the same is true for the WISC/WIAT combo, and that may give a clue to why your dd's scores are "predicted" at the level they are. So basically what you want to find out (which you might find on either your dd's report or by googling or by finding someone here who's familiar with WISC/WIAT combo reporting) is which ability+achievement subtest scores went into each prediction. Once you know that there are several things to consider: is there scatter in any of the subtests, particularly on the ability testing? How/in what order is each subtest score administered? Was the WISC given before the WIAT? Is it possible that any of the testing either isn't reflective of your dd's true ability (I'm referring to *under* estimating), or is it possible that whatever caused the lower processing speed score also impacted other scores on the WISC?

The other thing I'd consider is that an FSIQ of 134 is a really high FSIQ (not DYS level, but it's greater than 98th percentile). If she has a lower processing speed, I'm guessing that looking at her GAI (takes wm and processing speed out of the calculation) might be > 99th percentile. The WIAT scores your dd have are 99th percentile except for reading which is > 98th (I think... I am actually guessing the WIAT percentiles so I might be incorrect)... so when you look at the scores from that perspective, the achievement scores seem to make sense. What doesn't fully make sense to me is why are her predicted scores lower (which is different than wondering why her actual scores are so high). Again, I suspect that the key lies in understanding what her subtest scores are and which subtests go into the "prediction" calculation.

Can you ask your dd's tester what his/her impression is re why the actual results vs predicted are different?

Best wishes,

polarbear

tortuga, I agree with many of the PP. I would suspect that in your DD's case, the WISC FSIQ alone is not a great indicator of her potential or abilities. I do not have time to look up the sources at the moment, but I've recently read cautions about simply utilizing an FSIQ to understand a child's abilities. The GAI would probably be a better measure to understand her. Also, your DD may be an one of those children who simply performs better on a SB, or other type of test.

If someone doesn't beat me to it, I can try to post sources later.

My DD's FSIQ on the WISC is 135 or 136 and her GAI is 150 (155 if you calculate extended norms). The below 100 processing speed (with a particularly bad coding score) pulled her down a lot for FSIQ. Working memory was Ok at 96th percentile. I don't understand why the WISC puts so much emphasis on processing speed as a factor of intelligence. But processing speed is not going to affect achievement that much unless the achievement test is timed. She hasn't had the WIAT so I'm not sure how she'd do.