A priori, I prefer the more recent norms, which in this case means the WISC-V. My personal take is also that the structure of the WISC-V is better defined than the IV, as it separates the spatial and fluid reasoning dimensions of the PRI into their own index scores. As to the extended norms, they are of limited value this close to the top of the age range (which ends at 16-11). There are four subtests in the GAI for which she could attain extended scale scores at this age, and she would have to score within a point of the maximum possible raw score on each of them to do so. There is actually a little more headroom in the WISC-V norms for many of these subtests. (I.e., you don't have to be perfect to score 18 or 19).
