I just wanted to comment that in my case, I did all of the research you have done and it turned out that our Psychologist refused to calculate extended scoring and did not give us an accurate GAI. I did mention to her, before the testing began, that I wanted her to continue to ask questions until the termination criteria was met. (I truly think she did as I asked.) But when I also mentioned the possibility of my son hitting a ceiling and referred to extended scoring, I think it put off the tester, as if I knew more than they did.
It turns out that ds FSIQ was high enough, so I didn't have to press for extended scoring. (instead, I asked Dottie to help me calculate it! Thank you, Dottie!!)
It was not my goal to squeeze the absolute highest quantity from testing. I feel like I know my child pretty well (we homeschool.) I just wanted the opportunity to apply for DYS.
HTH
-cc
