Just for kicks, I asked DS to start at the 7 year old questions (he's 6 1/2). He did all through the 9 year old ones, then quit and said the 10s were too hard. So assuming he actually couldn't do any of the 10s and using his age as 6.5 it came out a slight underestimate of his actual tested FSIQ.

I'm not saying that in any way validates it, I just was curious!