It's not totally clear how the IQ/Index ranges will change, as they don't appear to have released that information yet, but there have been efforts made to strengthen the subtest floors and ceilings, which can only be to the good, in the event that extended norms are developed. Keeping scores in perspective, if you read the WISC-IV Technical Report #7, which has the extended norms in it, you'll note that exactly one child in 2,200 members of the standardization sample obtained a GAI of 151, and none obtained an FSIQ of 150+. So from a general utility standpoint, there is no particular value in going above 160 on the FSIQ chart, but maybe the stronger subtest ceilings will allow for a better extended norm chart.
I asked because I believe it was the N.A.G.C. that requested extended norms to differentiate gifted children. In a sample of 157 moderately gifted children (the average IQ was 135.1) the highest IQ and GAI attained were 159 and 176, respectively. Although the highest score one would expect in a sample of about 2,000 is about 150, I did not know that such scores were so rare. I know that the distribution among races is not necessarily normal (e.g., blacks have a pearson type IV distribution according to Jensen). Thank you for the information.
