In terms of accuracy, on general principle, I would say that the most accurate (and likely highest) number would be obtained from the English SB5 (assuming English is his stronger language).
The English WPPSI-III would likely be the next preferred instrument, as ceiling issues, while always a real concern for very high functioning learners, are not as concerning to me in this case, as the age range of the instrument goes up to 7-3.
A brief internet search finds that the (test in second language) is viewed as better for discriminating intelligence at the lowest end of the curve than other instruments, and not preferred for discriminating above IQ 120. It does have the advantage that it is less verbally-loaded, and might not have as much of a penalty for testing in the weaker language.
Last edited by aeh; 09/21/17 04:12 AM. Reason: OP privacy
