And excellent point about having a 80% agreement over the thick part of the bell curve doesn't say anything about what's going on at +2SD and +3SD.
cricket2 and Grinity - As far as assessment goes, 80% is that magic number that test makers look for. I think the CogAT is even a little over 80%, and that is pretty much the best you can ask for. The SAT and ACT would have similar numbers for predictive validity (in terms of college performance).
I think that the 80% validity is overall, but that this may translate to greater validity for within 2SDs , with >2SD having much weaker, or even negative, correlation. I don't know if they have studies about the tail ends of the distribution, but I didn't find anything on a quick search. From the stories on here, it seems like it might be due to some out-of-the-box thinking going on with those HG kids.
I think that the CogAT is also a good measure of predicted academic achievement in a totally normal at-grade class setting. So the kids who score high on the CogAT are probably going to be great students and high-achievers, without (necessarily) needed any intervention. They might not think so differently than would be expected for their age, so they are not going to have to wonder which answer the teacher wants. Sometimes having a gifted brain (I know from experience) lets you see the possibilities in all of the answers, so it takes some maturity, experience, or even a separate skill set to pick the right one for the right reasons.
DD7's situation with a high CogAT (139) and a much lower WISC GAI (121) seems to be much less common that the other way around. In fact, I haven't found any other parents complaining about it online at all! I personally wish that my school district would take a look at DD7's quantitative CogAT score (150-ceiling) and would allow her to accelerate in math. They do let a small group of kids do this in 3rd grade, and I'm hoping that they will let her participate next year, regardless of her gifted status at that time. I don't know...I'm still thinking about having her tested again privately, maybe with the SB-V. She is so primed for accelerated math learning (she always complains of math in school being boring because they go so slow, she takes in new concepts super-quickly, etc) and she is also a very strong reader (about 5th grade when she was in 1st, has been reading great above-level books all summer) and all-around good student. In her case, I would just like to have her in the enrichment program, because I think it would make school much more interesting for her.
