The WJ does generate IQ type scores (GIA), but it tends to favor fast, verbal kids. There is no real equivalent to the WISC GAI score, that lessens the impact of processing speed and working memory (cognitive proficiency).
FWIW, my ds (low PSI on WISC due to fine motor dysgraphia) scored in a similar range on GIA on WJ-III Cog as he did on the WISC GAI (his FSIQ was lower due to PSI score). I actually found the WJ-III Cog test more useful than the WISC for each of my kids - it caught a memory challenge with my younger dd that was hidden on the WISC. In a bit of a rush now so no time to really explain. In general I felt that my ds' particular challenge (fine motor) actually impacted him less on the WJ-III.
Our school district also prefers to use the WJ-III Cog over the WISC because they believe it doesn't ceiling out as quirky for highly gifted children. Don't know if that's true or not, but that's what we were told by our school psych.
polarbear
