Thanks aeh for taking the time to respond, and thanks for the clarifications. My problems seem to have arisen fromt here being a policy vacuum here - the school system says that the Iowa Acceleration scale is to be used, but provides no further guidance - leaving it for school psychs to figure it out for themselves.
Sorry, I was rather vague in my original question. My specific issue is not with use of the WIAT-III or the (grade) norm used, but rather with how the WIAT-III results were translated into the Achievement section (Section VI) of the IAS-3. This is what was done:
IAS-3 Section VI (Achievement - max 8 points)
'Vocabulary' (2 points) - scored solely from the 'Vocabulary' sub-test score of the WISC-V
'Total Reading' (2 points) - scored solely from the 'Reading (Early Reading Skills)' composite of the WIAT-III
'Total Math' (2 points) - scored solely from the 'Mathematics' composite of the WIAT-III (in isolation, this one actually makes sense)
'Total Language' (2 points) - scored solely from the 'Oral Language' composite of the WIAT-III
'Other' (2 points) - Not used, despite there being unused composites from the WIAT-III available.
The 'Total Achievement Score' from the WIAT-III was available and reported by the psych, but ignored for IAS purposes. Ditto the 'Written Expression' composite. As a non-expert, I would imagine that if the WIAT-III is the instrument chosen to measure achievement for IAS purposes, then the appropriately weighted, full-scale 'Total Achievement' score that the WIAT-III provides is the most valid and reliable measure? What rational could there be for not using the full-scale score in for this purpose?
Likewise, written expression is presumably an important component of total achievement, so I'd contend it's not a good idea to exclude it? (important in our case, as daughter's standard score for this composite was 140, 99.6th %ile - one of her highest composites, but not taken into account at all!)
The use of WISC-V in the Achievement section seems contrary to the explicit instructions in the IAS manual (i.e. it is an Ability test rather than an Achievement test). And then there are the statistical issues with recycling the same data in two sections, and of inflating just one WISC-V sub-test (out of 10 taken) to score fully one quarter of achievement...
So my specific question is, what is the validity of this approach to scoring achievement in the IAS? It appears that the psych has not had the opportunity to read the IAS-3 Manual and related literature closely. The approach taken appears to have been to look at the categories suggested on the IAS-3 form, and against each scored whichever composite/subtest score most closely matched the name of the category. There is no evidence of consideration being given to whether or not this approach might actually reflect the child's academic attainment. My reading of the IAS-3 Manual suggests the categories are guides only, to help in cases where data from different sources needs to be combined.
Unfortunately the school psych is unwilling to specifically address any of these points, or revisit their method.
Am I mistaken in my belief that the approach taken is of questionable validity, and contrary to the intention of the IAS?
W
