There are a number of reasons I would not be particularly alarmed at the changes in her cognitive scores, especially if you have not seen functional concerns:
1. Scores at age six or seven tend to be less stable than at 12 or 13. All things considered, these scores are not too far off of each other. Her full scale cognitive measure has actually risen slightly.
2. The SB and the WISC do not have the same structure, so direct comparisons will be approximate at best. For example, there is no equivalent to QR on the WISC-IV. WM on the SB includes both auditory and visual memory, while the WISC-IV has only auditory. FR has no real cluster equivalent on the WISC-IV, although the nonverbal half of it is most similar to matrix reasoning from the PRI. At age six, though, portions of the FR tasks may have been quite different, as the lower age levels are not matrix tasks. The verbal FR task on the SB is most like Similarities from the WISC VCI. The SB has no PSI.
WRT the WJ, I suspect the differences reflect changes in expectations between age seven and age 13, and the ebb and flow of your daughter's development (which, for most GT kiddos, is not just linearly advanced compared with age-mates, but is shaped differently). In first grade, many children can decode, but not too many can do anything beyond single-digit addition and subtraction. If she had any calculation or math reasoning skills beyond that, it would have been relatively easy to blow the top off the norms. By seventh grade, just about everyone can decode, but comprehension is what spreads the curve. Her VCI sets her apart from age-mates. Math, on the other hand, is more closely associated with PRI and WMI. It is also rather dependent on exposure, once one passes arithmetic. In order to push the upper end of the norms at the older age, she would need to know some advanced math, in which (depending on your schooling situation) she may not have received instruction.
Take home:
1. I wouldn't be concerned about the changes in cognitive scores.
2. I wouldn't necessarily be concerned about the changes in achievement scores, except with regard to possible access issues in contemplating instructional planning for mathematics.
