To put it into perspective, in the US about 400 graduating high school students a year will have a GAI that high or higher. Of course, there will also be about 400 who have FSIQ that high or higher, who are a few points lower, but harder working, etc, etc. But that gives you an idea of the numbers involved.
It's not an exact science so far from the mean, but that's a score so high that it's unlikely your child's school has ever had a similar child. Seriously. There's as much difference between your child and those who qualify for the gifted program as there is between them and the average student. IIRC, 130 IQ is about 1 in 44, and more common in higher SES/ highly educated places. For example the district I just googled has a threshold of 95% on the OLSAT, and 10% of their students qualify.
Personally, I'd join Davidson.to get help with the advocacy.
Another factor is that it's a bit easier to get a high score if you pick your best score out of FSIQ, GAI, VCI, PRI, etc.
A couple of people asked how this is relevant. All the scores are calculated independently, not all kids have a FSIQ as far from the mean as their GAI. You could have a 50+ point spread between the lowest and highest of the scores. The set of people with PCI over 145 overlaps but is not the same as the set of people with 145+ IQ or the set of people with 145+ GAI, etc. 22B is trying to reassure you. It's not quite as dire a situation as the rarity of that one score suggests.
Aeh can probably explain it better and more correctly, but this is my understanding.
