You'll need the WISC Technical Report #4: http://www.ksde.org/Portals/0/Special%20Education%20Services/gifted/WISCIVTechReport4.pdf

The discrepency btwn his PRI and WMI scores would warrant utilizing an GAI instead of a FSIQ, but you will need the scaled scores for the tests within the VCI and PRI indices to calculate the GAI. Do you have those?

Without those, some of us with kids whose VCI and PRI totals weren't far off of your dc's might be able to ballpark a figure for you. My younger dd's VCI was a hair lower than your dc's and her PRI was a bit higher, but overall they were quite close. Based on her GAI from that testing, I'd venture to guess that you'd be looking at a GAI around 144 with those scores.

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