As I learn more about IQ testing, I've come to understand that not everyone with a certain IQ score achieves index scores that match due to ceiling effects. I was wondering if there have been any studies conducted on tests with extended norms showing the mean increase (when the extended norms are applied) in each subtest and/or mean increases in the index scores? Specifically with regard to number of ceilings reached and (this may be wishful thinking) with regard to qualitative observations during test sessions? It'd be interesting to see how the correlations change, and the data could be useful for admission to gifted programs as well.
